Thursday, September 18, 2008
Self Reflection and Evaluation
I am coming away from unit one with a new, deeper understanding of cells, systems, genetic characteristics, and how life is formed. I thought we covered alot of information in the book, online and the labs we did. I think I know what to expect more so now than I did prior to jumping into Unit One. What a LARGE amount of work!!! I am really proud of myself!I have enjoyed myself and also gained a sense of accomplishment by creating my cell project and also working with the microscope simulator. I enjoyed the Powerpoint presentations ALOT and it gave me a great place to start to open my mind and understand what the material was going to cover in the unit. I learned alot and think I will retain a big portion of it for the future.
Dragon Genetics and Punnett Square Probabilities
The Dragon simulator showed me how to manipulate the alleles, (genotypes) of two Parent Dragons *which means basically I got to mess around with the DNA gene material that came from the Father and Mother Dragon to combine in some way that would give Baby Leonard Dragon his distinct characteristics. As I manipulated the alleles, I was causing changes to the baby Dragons appearance (phenotype).
The Punnett Square can use "Probability" to give a percentage (%) of chance as to a certain genotype being present in offspring. The Punnett Simulator gave me fruit flies to work with.
With the DNA genetic information/homozygousLL and a heterozygousLI the probability is 50% for either the homo or the hetero all offspring will be long winged from these two geno-pools.
The Punnett Probability comes from a square diagram with all of the possibilities in boxes and accounted for.
It would look like this:LL/LL and LI/LI
Genetic Changes in Our Food Supply
Ethical Issue/ Topic Unit One:
The ethical question I am reflecting on in my paper is from the article from our web link titled, “Mother’s for Natural Law”. This website looks at examples of genetically altered foods that are dispersed to the public and then consumed on a regular basis. The article claims that the majority of consumers are completely unaware that they are purchasing and consuming genetically altered vegetables, as well as feeding them to their families.
Molecular scientists are able to manipulate cell DNA by changing/altering the enzymes that are used during DNA replication and protein synthesis. Scientists have also been studying certain types of viruses’ (DNA vectors) that can invade the DNA information center and then alter the chemical make-up for future generations of cells within the organism. Scientists are inserting “desirable” DNA molecules into other cells to change the organism’s chemical mapping, so characteristics will develop that are considered better or more practical in some way.
I think these types of genetic alterations need to be studied well before they are used for general practice. Being able to genetically manipulate a tomato to withstand frost and cold weather, thus helping to ensure a long growing season, sounds like a positive thing to do .Common sense says that by manipulating the DNA, the farmer safeguards his crop income and consumers stand a better chance of not seeing a price spike due to shortages in the supply of tomatoes. Suppose though, that the DNA that is altered in the laboratory, actually works against a chemical chain that is within the human/animal organism. What happens once the two are introduced to one another, and the altered DNA in the food chain collides with the living organism’s DNA and the conversion system starts unfolding? What if ,as the body starts the food to energy break down, it is recognized as “toxic” and something goes terribly haywire in the protein folding process?
I believe altering living organisms should be done carefully and also thoughtfully. Ethically and morally, I want to be informed of what I am putting into my body, and just as importantly, I want to know what I am feeding to my family. I want to be informed so I can then make my own choices and decisions about what to do.
Two of the arguments I agree with that speak against genetically altering food are, lack of test studies, and food having less nutritional value. I personally believe that changing anything in the natural order of the world will have a consequence. To me this is simply, “Cause and Effect” in it’s most basic form. I am a firm believer that everything that occurs in our world has to have an outcome; energy in/energy out. It’s that simple! The consequence could be positive or negative. Only time will be able to tell the true story.
The argument of less nutritional value seems to make sense to me and is something I am concerned about for my own family. I think that by harvesting crops prior to ripening naturally, we run the risk of losing out on much of what nature has to give to us nutritionally. Fruits and vegetables that have been genetically altered to sit on store shelves for longer periods of time without rotting, have lost at least the garden fresh, farm grown aroma, that I grew up with in Iowa on my families farm. In reflection, I can’t tell you how long its been since I’ve actually smelled “fresh vegetables” in my local produce department! As for the wonderful tastes I remember as a kid, those are long gone as well. I have often wondered whatever happened to the way “Iowa’ vegetables used to smell and taste going back 30 years or so ago when I was growing up.
In conclusion, although I believe good things can be learned and also gained with genetic studies, I firmly believe we as human beings have a moral and ethical responsibility to take these types of things slowly and act cautiously and highly conscientiously above everything else.
The ethical question I am reflecting on in my paper is from the article from our web link titled, “Mother’s for Natural Law”. This website looks at examples of genetically altered foods that are dispersed to the public and then consumed on a regular basis. The article claims that the majority of consumers are completely unaware that they are purchasing and consuming genetically altered vegetables, as well as feeding them to their families.
Molecular scientists are able to manipulate cell DNA by changing/altering the enzymes that are used during DNA replication and protein synthesis. Scientists have also been studying certain types of viruses’ (DNA vectors) that can invade the DNA information center and then alter the chemical make-up for future generations of cells within the organism. Scientists are inserting “desirable” DNA molecules into other cells to change the organism’s chemical mapping, so characteristics will develop that are considered better or more practical in some way.
I think these types of genetic alterations need to be studied well before they are used for general practice. Being able to genetically manipulate a tomato to withstand frost and cold weather, thus helping to ensure a long growing season, sounds like a positive thing to do .Common sense says that by manipulating the DNA, the farmer safeguards his crop income and consumers stand a better chance of not seeing a price spike due to shortages in the supply of tomatoes. Suppose though, that the DNA that is altered in the laboratory, actually works against a chemical chain that is within the human/animal organism. What happens once the two are introduced to one another, and the altered DNA in the food chain collides with the living organism’s DNA and the conversion system starts unfolding? What if ,as the body starts the food to energy break down, it is recognized as “toxic” and something goes terribly haywire in the protein folding process?
I believe altering living organisms should be done carefully and also thoughtfully. Ethically and morally, I want to be informed of what I am putting into my body, and just as importantly, I want to know what I am feeding to my family. I want to be informed so I can then make my own choices and decisions about what to do.
Two of the arguments I agree with that speak against genetically altering food are, lack of test studies, and food having less nutritional value. I personally believe that changing anything in the natural order of the world will have a consequence. To me this is simply, “Cause and Effect” in it’s most basic form. I am a firm believer that everything that occurs in our world has to have an outcome; energy in/energy out. It’s that simple! The consequence could be positive or negative. Only time will be able to tell the true story.
The argument of less nutritional value seems to make sense to me and is something I am concerned about for my own family. I think that by harvesting crops prior to ripening naturally, we run the risk of losing out on much of what nature has to give to us nutritionally. Fruits and vegetables that have been genetically altered to sit on store shelves for longer periods of time without rotting, have lost at least the garden fresh, farm grown aroma, that I grew up with in Iowa on my families farm. In reflection, I can’t tell you how long its been since I’ve actually smelled “fresh vegetables” in my local produce department! As for the wonderful tastes I remember as a kid, those are long gone as well. I have often wondered whatever happened to the way “Iowa’ vegetables used to smell and taste going back 30 years or so ago when I was growing up.
In conclusion, although I believe good things can be learned and also gained with genetic studies, I firmly believe we as human beings have a moral and ethical responsibility to take these types of things slowly and act cautiously and highly conscientiously above everything else.
Unit One Lab Project-Build a Cell
My Lab Project: Part One
Building a basic cell was fun, challenging, and interesting! I actually learned alot about, and semi-memorized, the parts to a human cell by putting the pieces together. below is a picture of the items I used for my cell model:
I used a large serving plate for my cell structure and the biscuit dough was great cytoplasm, as it helped hold all the other pieces in place. On my cell model I include the main components,membrane (yellow icing) cytoplasm (biscuit dough), endoplasmic reticular (rough and smooth) made with (green licorice and gummi nerds),ribosomes (cookie dots), golgi body (green and white folded paper), mitochondrion (rice cakes and gummi worms), nuclear membrane (orange peel), nucleolus (big marble), Lysosome (red gummi bears, nucleus (orange), and vacuole (rolled gummi worms.
*see below for completed basic cell.
The 3-D effect and also the colors made the working pieces make more sense to me.
The workings of a cell:
Inside the nucleus is stored the DNA blue print for an entire human being. The cytoplasm is the jelly like fluid that helps protein and enzyme synthesis and also is necessary for the processes of RNA/mRNA, and tRNA. The mitochondrion is where energy for the cell is created, and the ribosomes are where the amino acids are processed and the proteins are synthesized.The endoplasmic reticulum (2) and the ribosomes are important in the DNA/RNA replication and transcription/translation processes. Cell replication is constantly going on in a living body, the average healthy cell divides in to a new duplicate copy approximately 60-70 times before it dies! Each and every one of us literally has trillions of living cells in our bodies and old ones are constantly dying and new ones are being formed!
Building a basic cell was fun, challenging, and interesting! I actually learned alot about, and semi-memorized, the parts to a human cell by putting the pieces together. below is a picture of the items I used for my cell model:
I used a large serving plate for my cell structure and the biscuit dough was great cytoplasm, as it helped hold all the other pieces in place. On my cell model I include the main components,membrane (yellow icing) cytoplasm (biscuit dough), endoplasmic reticular (rough and smooth) made with (green licorice and gummi nerds),ribosomes (cookie dots), golgi body (green and white folded paper), mitochondrion (rice cakes and gummi worms), nuclear membrane (orange peel), nucleolus (big marble), Lysosome (red gummi bears, nucleus (orange), and vacuole (rolled gummi worms.
*see below for completed basic cell.
The 3-D effect and also the colors made the working pieces make more sense to me.
The workings of a cell:
Inside the nucleus is stored the DNA blue print for an entire human being. The cytoplasm is the jelly like fluid that helps protein and enzyme synthesis and also is necessary for the processes of RNA/mRNA, and tRNA. The mitochondrion is where energy for the cell is created, and the ribosomes are where the amino acids are processed and the proteins are synthesized.The endoplasmic reticulum (2) and the ribosomes are important in the DNA/RNA replication and transcription/translation processes. Cell replication is constantly going on in a living body, the average healthy cell divides in to a new duplicate copy approximately 60-70 times before it dies! Each and every one of us literally has trillions of living cells in our bodies and old ones are constantly dying and new ones are being formed!
Lab Project;Part two
The second part of my lab project was to show that I understand DNA replication and the workings of DNA, RNA, tRNA, mRNA. The processes of Transcription (which takes place within the nucleus) and Translation (which occurs OUTSIDE the nucleus in the cell cytoplsm) are when the DNA/RNA strands are in process of completion and they need the amino acids/proteins to go through synthesis and combining to complete the steps in new cells being formed. My first picture shows DNA Double Helix, which looks like a twisted ladder. The DNA Double Helix replicates into new DNA by keeping one base (parental) and replicating the other one brand new (daughter strand). All of this takes place in the nucleus up until this part of the process.
DNA EXIST IN NUCLEUS-
PROTEIN SYNTHESIS OCCURS IN CYTOPLASM-
FIRST mRNA TAKES COPY OF DNA BLUEPRINT TO CYTOPLASM-
NEXT 20+ t RNA MOLECULES BRING ABOUT PROTEIN SYNTHESIS ALSO IN CYTOPLASM-
TRANSCRIPTION-
STRAND OF (mRNA) FORMS THAT IS COMPEMENTARY TO PART OF DNA (INSIDE NUCLEUS)-
THIS DNA “COPY” TRAVELS OUT SIDE NUCLEUS TO RIBOSOMES TO BECOME PROTEIN (SYNTHESIS)-
TRANSCRIPTION BEGINS WITH ENZYME RNA POLYMERASEOPENING DNA HELIX (IN NUCLEUS) THIS IN TURNS CREATES (m RNA) AS EXACT COPY OF DNA BASES ( IT IS PROCESSED AND THEN OUT IN CYTOPLASM IT GOES!)-
TRANSLATION-
PROCESS OF TRANSLATION IS NECESSARY FOR PROTEIN SYNTHESIS-
SEQUENCE OF NUCLIOTIDES IS TRANSLATED INTO SEQUENCE OF AMINO ACIDS (OUTSIDE NUCLEUS, IN CYTOPLASM)-
BASES OF DNA AND (mRNA) MUST “CODE” FOR AMINO ACIDS FOR PROCESS TO WORK!
TRANSCRIPTION BEGINS WITH ENZYME RNA POLYMERASEOPENING DNA HELIX (IN NUCLEUS) THIS IN TURNS CREATES (m RNA) AS EXACT COPY OF DNA BASES ( IT IS PROCESSED AND THEN OUT IN CYTOPLASM IT GOES!)
Working on the second part of "Building A Cell" was difficult for me! Some of the process didn't make sense to me or else it seemed extremely difficult for me to grasp. The time and effort I put into piecing together the nucleus "how it all works" and the transcription/translation "how it all works", I had a much better basic knowledge of what happens at a cellular level in our bodies.
Tuesday, September 16, 2008
Compendium Review Unit One:Part Two-Genetics/Chapters 18-21
My Compendium Review is organized by chapter sequence, followed by the sub-topics within the chapters. Information from the Power point presentation is also presented within the topic
range throughout.
Chapter Eighteen, “Patterns of Chromosome Inheritance”
18.1 Chromosomes and the Cell Cycle
Humans have 2 sets of 23 chromosomes (46 total chromosomes)/ twenty-two pairs are autosomes and the remaining pair is called the sex chromosome because it controls gender.
XY chromosomes represent male
XX chromosome represent female
In the Y chromosome the gene SRY is present and this gene causes male testes to develop.
Red blood cells lack a nucleus, however all other cells contain a nucleus and therefore can be studied through their chromosome make-up.
XY chromosomes represent male
XX chromosome represent female
In the Y chromosome the gene SRY is present and this gene causes male testes to develop.
Red blood cells lack a nucleus, however all other cells contain a nucleus and therefore can be studied through their chromosome make-up.
Karyotype-
pairs of chromosomes are numbered- Chromosomes are duplicated and each is composed of two (2) sister chromatids.
Karyotypes tell much information about a cell.
A normal body cell is “Diploid”.
Mitosis- means duplication division
Sister Chromatids- refers to within dividing cells, each chromosome is composed of two identical parts. Process is possible because each chromatid contains a DNA double Helix.
When Daughter Chromosomes separate, the new cells get one of each kind, making a full complement of chromosomes.
Centromere hold chromatids together until a certain phase of Mitosis.
Cell Cycle-The cell cycle is an orderly process that has two parts:
(1) interphase- most of the cell cycle is spent in interphase. During interphase the cell is in routine function, then it gets ready to divide, it grows larger, the number of organelles double, chromatin doubles as DNA synthesis occurs in humans interphase happens for approximately 20 hours, *which accounts for 90% of cell cycle.
DNA synthesis is responsible for interphase having three stages.
Stage one- G1 stage-cell doubles
Stage two- S stage-DNA replication occurs
Stage three-G2 stage-cell synthesizes protein necessary for cell division.
Some cells, such as nerve and muscle cells never complete the interphase cycle, they stay in G1 permanently, which is then referred to as Go.
Embrionic cells on the other hand spend minimal time in the G1 stage and actually complete cell cycle in a few hours.
(2) cell division-Occurs after interphase- consists of two stages: (1) M*(for Mitotic)-type of nuclear division (2) -Cytokinesis- division of the cytoplasm.
Science Focus (pg.380) Obtaining fetal chromosomes can show parents and physicians the cellular/genetic make-up of an unborn child. Syndromes, such as, Downs Syndrome, can be discovered by performing Amniocentesis. A long needle is used to withdraw amniotic fluid from the uterus. The fluid contains fetal cells and will show if the fetus chromosomes are normal or if there are three number 21 chromosomes instead of two as there should be.
18.2 Mitosis
Mitosis is “duplication division”. The cell that divides is called the “Parent Cell” and the new cells are called “Daughter Cells”. The nuclei of the two cells have the exact same number and kinds of chromosomes as the dividing cell.
The complete number of chromosomes is called the “diploid”.
During Mitosis duplication of the Centrosome occurs. Chromosomes are attached to the spindle fibers and an aster is also at the poles. Spindle fibers can lengthen and shorten due to their physical make-up. This ability to change in length ultimately causes the movement of the chromosomes.
pairs of chromosomes are numbered- Chromosomes are duplicated and each is composed of two (2) sister chromatids.
Karyotypes tell much information about a cell.
A normal body cell is “Diploid”.
Mitosis- means duplication division
Sister Chromatids- refers to within dividing cells, each chromosome is composed of two identical parts. Process is possible because each chromatid contains a DNA double Helix.
When Daughter Chromosomes separate, the new cells get one of each kind, making a full complement of chromosomes.
Centromere hold chromatids together until a certain phase of Mitosis.
Cell Cycle-The cell cycle is an orderly process that has two parts:
(1) interphase- most of the cell cycle is spent in interphase. During interphase the cell is in routine function, then it gets ready to divide, it grows larger, the number of organelles double, chromatin doubles as DNA synthesis occurs in humans interphase happens for approximately 20 hours, *which accounts for 90% of cell cycle.
DNA synthesis is responsible for interphase having three stages.
Stage one- G1 stage-cell doubles
Stage two- S stage-DNA replication occurs
Stage three-G2 stage-cell synthesizes protein necessary for cell division.
Some cells, such as nerve and muscle cells never complete the interphase cycle, they stay in G1 permanently, which is then referred to as Go.
Embrionic cells on the other hand spend minimal time in the G1 stage and actually complete cell cycle in a few hours.
(2) cell division-Occurs after interphase- consists of two stages: (1) M*(for Mitotic)-type of nuclear division (2) -Cytokinesis- division of the cytoplasm.
Science Focus (pg.380) Obtaining fetal chromosomes can show parents and physicians the cellular/genetic make-up of an unborn child. Syndromes, such as, Downs Syndrome, can be discovered by performing Amniocentesis. A long needle is used to withdraw amniotic fluid from the uterus. The fluid contains fetal cells and will show if the fetus chromosomes are normal or if there are three number 21 chromosomes instead of two as there should be.
18.2 Mitosis
Mitosis is “duplication division”. The cell that divides is called the “Parent Cell” and the new cells are called “Daughter Cells”. The nuclei of the two cells have the exact same number and kinds of chromosomes as the dividing cell.
The complete number of chromosomes is called the “diploid”.
During Mitosis duplication of the Centrosome occurs. Chromosomes are attached to the spindle fibers and an aster is also at the poles. Spindle fibers can lengthen and shorten due to their physical make-up. This ability to change in length ultimately causes the movement of the chromosomes.
There are four phases of Mitosis. These stages flow from one to the next phase in a continuous manner. The four phases are as follows:
(1) Prophase-during this stage the cell is preparing to divide. The coatrooms outside the nucleus have duplicated, and begin moving away from one another toward opposite ends of the nucleus. Spindle fibers appear between the separating chromosomes- nuclear envelope begins to fragment-special region of DNA, called the nucleolus, disappears as chromosomes condense. Now the chromosomes become visible. Each chromosome is composed of two “Sister Chromatids”. During Prophase chromosomes randomly placed in the nucleus.
(2) Metaphase-during this phase the nuclear envelope is fragmented and spindle occupies region formerly occupied by the nucleus. The chromosomes are now at the center- fully formed spindle. (3) Anaphase-beginning of this phase, the centromeres uniting the sister chromatids divide. Characteristic of this phase is the diploid number of chromosomes move toward each pole. The number of centromeres indicates number of chromosomes, therefore if there are two centromeres than there will also be two chromosomes.
(4) Telophase-begins when the chromosomes arrive at the poles. The chromosomes become indistinct chromatin once again. The spindle disappears as nuclear envelope components reassemble in each cell. This phase characterized by the presence of two daughter nuclei.
Cytokinesis is the division of the cytoplasm and the organelles. A ‘Cleavage Furrow” passes around the circumference of the cell and to me it resembles a peanut shell body. This cleavage furrow eventually pinches the cell in half and it then becomes enclosed in its own plasma membrane.
18.3 Meiosis
There are two cell divisions during Meiosis;
(1)Meiosis I- Homologous chromosomes pair then separate- Only during Meiosis I is it possible to observe chromosomes at equator.
(2)Meiosis II- Sister chromatids separate, results in four cells with haploid number of chromosomes that move into Daughter nuclei.
Results in genetic recombination due to crossing over.
Overview of Meiosis
In the beginning, parent cell is 2n, chromosomes occur in pairs.*(Think of it as a pair of short chromosomes and a pair of long chromosomes.) The members in each pair are called “homologous chromosomes”. These chromosomes carry genes for the SAME traits because they look alike, such as hair color and eye color.
In humans the Daughter cells mature into gametes (sex cells, egg and sperm). Fertilization restores diploid number of chromosomes in the zygote, *which is the first cell of new individual.
The four stages of Meiosis I and Meiosis II are similar but designated with a I or II.
Stages of Meiosis
Meiosis is part of sexual reproduction, which ensures next generation will have diploid number of chromosomes and combined characteristics different from either parent.
(1) Prophase I- synapsis occurs then spindle appears, while nuclear envelope fragments and nucleolus disappears, exchange of genetic material may occur, *called crossing-over.
(2) Metaphase I- Homologous pairs align independently at equator. Maternal or paternal member may be oriented toward either pole. *There are eight (8) possible orientations for a cell that contains three pairs (6 total) chromosomes…the first four combinations result in gametes that have DIFFERENT characteristics and the next four combinations will result in the same gametes. The significance of Meiosis is that it keeps the chromosome number constant from one generation to the next.
“Asexual Reproduction” which occurs in bacteria and protozoans (unicellular organisms) is done by binary fusion.
18.4 Comparisons of Meiosis and Mitosis
Prophase I homologous chromosomes pair/there is NO pairing in Mitosis.
Metaphase I homologous duplicated chromosomes align at the equator.
Anaphase I homologous chromosomes separate.
Meiosis only occurs at certain times in the life cycle of sexually reproducing organisms. Spermatogenesis (part of Meiosis) is production of sperm in the males and Oogenesis (part of Meiosis) is production of eggs in females. *Following Meiosis the daughter cells mature to become the gametes.
18.5 Chromosome Inheritance
Individuals normally get 22 pairs of autosomes and two sex chromosomes.
Nondisjunction changes chromosome number in the gametes, causing trisomy or monosomy.
Down Syndrome is an autonomic trisomy (trisomy 21)-three copies of chromosomes 21 because egg had two copies instead of one copy. Older women are much more likely to give birth to Downs Syndrome baby.
Turner Syndrome, (XO) which can only be female, is characterized by individual having only one sex chromosome, an X.
Klinefelter Syndrome, *referred to “47” in reference to number of chromosomes, (XXY) can only occur in males. Common characteristics are speech and language delay.
Changes in Chromosome Structure are another type of chromosomal mutation. Environmental agents like radiation, some organic chemicals, and viruses, can cause chromosomal breakage.
When chromosomes break the two broken ends normally re-unite for same gene sequence, but sometimes at least one chromosome fails to re-join in same pattern as before and the result is chromosomal mutation.
“Changes” in chromosomes can be (1)deletions (2)translocations (3)duplications (4)inversions of chromosome segments.
“Deletion” occurs when a chromosome end breaks off or two simultaneous breaks lead to the loss of an internal segment. Even single deletions can cause abnormalities.
“Duplication” presence of a chromosomal segment more than once in the same chromosome.
“Inversion” is a segment 180 degree turn around, this reversal can then lead to altered gene activity such as deletions and duplications.
“Translocation” movement of chromosome segment from one chromosome to another no homologous chromosome. Downs Syndrome is sometimes caused by chromosome 21 being attached to chromosome 14 in the previous generation and can run in either the mother or father’s family gene pool.
Changes in the human chromosome structure lead to Syndromes that are just recently being studied. “Deletion Syndrome’ 8children have characteristics of pixie-ish looks, poor academic skills, however, excel in music and verbal skills. Skin ages prematurely and cardiovascular problems occur due to the protein elastin being missing in their bodies.”Cri du chat Syndrome” *Deletion syndrome where the end of chromosome 5 is missing. distinctive cry is like a cat, small head and mental retardation.
(1) Prophase-during this stage the cell is preparing to divide. The coatrooms outside the nucleus have duplicated, and begin moving away from one another toward opposite ends of the nucleus. Spindle fibers appear between the separating chromosomes- nuclear envelope begins to fragment-special region of DNA, called the nucleolus, disappears as chromosomes condense. Now the chromosomes become visible. Each chromosome is composed of two “Sister Chromatids”. During Prophase chromosomes randomly placed in the nucleus.
(2) Metaphase-during this phase the nuclear envelope is fragmented and spindle occupies region formerly occupied by the nucleus. The chromosomes are now at the center- fully formed spindle. (3) Anaphase-beginning of this phase, the centromeres uniting the sister chromatids divide. Characteristic of this phase is the diploid number of chromosomes move toward each pole. The number of centromeres indicates number of chromosomes, therefore if there are two centromeres than there will also be two chromosomes.
(4) Telophase-begins when the chromosomes arrive at the poles. The chromosomes become indistinct chromatin once again. The spindle disappears as nuclear envelope components reassemble in each cell. This phase characterized by the presence of two daughter nuclei.
Cytokinesis is the division of the cytoplasm and the organelles. A ‘Cleavage Furrow” passes around the circumference of the cell and to me it resembles a peanut shell body. This cleavage furrow eventually pinches the cell in half and it then becomes enclosed in its own plasma membrane.
18.3 Meiosis
There are two cell divisions during Meiosis;
(1)Meiosis I- Homologous chromosomes pair then separate- Only during Meiosis I is it possible to observe chromosomes at equator.
(2)Meiosis II- Sister chromatids separate, results in four cells with haploid number of chromosomes that move into Daughter nuclei.
Results in genetic recombination due to crossing over.
Overview of Meiosis
In the beginning, parent cell is 2n, chromosomes occur in pairs.*(Think of it as a pair of short chromosomes and a pair of long chromosomes.) The members in each pair are called “homologous chromosomes”. These chromosomes carry genes for the SAME traits because they look alike, such as hair color and eye color.
In humans the Daughter cells mature into gametes (sex cells, egg and sperm). Fertilization restores diploid number of chromosomes in the zygote, *which is the first cell of new individual.
The four stages of Meiosis I and Meiosis II are similar but designated with a I or II.
Stages of Meiosis
Meiosis is part of sexual reproduction, which ensures next generation will have diploid number of chromosomes and combined characteristics different from either parent.
(1) Prophase I- synapsis occurs then spindle appears, while nuclear envelope fragments and nucleolus disappears, exchange of genetic material may occur, *called crossing-over.
(2) Metaphase I- Homologous pairs align independently at equator. Maternal or paternal member may be oriented toward either pole. *There are eight (8) possible orientations for a cell that contains three pairs (6 total) chromosomes…the first four combinations result in gametes that have DIFFERENT characteristics and the next four combinations will result in the same gametes. The significance of Meiosis is that it keeps the chromosome number constant from one generation to the next.
“Asexual Reproduction” which occurs in bacteria and protozoans (unicellular organisms) is done by binary fusion.
18.4 Comparisons of Meiosis and Mitosis
Prophase I homologous chromosomes pair/there is NO pairing in Mitosis.
Metaphase I homologous duplicated chromosomes align at the equator.
Anaphase I homologous chromosomes separate.
Meiosis only occurs at certain times in the life cycle of sexually reproducing organisms. Spermatogenesis (part of Meiosis) is production of sperm in the males and Oogenesis (part of Meiosis) is production of eggs in females. *Following Meiosis the daughter cells mature to become the gametes.
18.5 Chromosome Inheritance
Individuals normally get 22 pairs of autosomes and two sex chromosomes.
Nondisjunction changes chromosome number in the gametes, causing trisomy or monosomy.
Down Syndrome is an autonomic trisomy (trisomy 21)-three copies of chromosomes 21 because egg had two copies instead of one copy. Older women are much more likely to give birth to Downs Syndrome baby.
Turner Syndrome, (XO) which can only be female, is characterized by individual having only one sex chromosome, an X.
Klinefelter Syndrome, *referred to “47” in reference to number of chromosomes, (XXY) can only occur in males. Common characteristics are speech and language delay.
Changes in Chromosome Structure are another type of chromosomal mutation. Environmental agents like radiation, some organic chemicals, and viruses, can cause chromosomal breakage.
When chromosomes break the two broken ends normally re-unite for same gene sequence, but sometimes at least one chromosome fails to re-join in same pattern as before and the result is chromosomal mutation.
“Changes” in chromosomes can be (1)deletions (2)translocations (3)duplications (4)inversions of chromosome segments.
“Deletion” occurs when a chromosome end breaks off or two simultaneous breaks lead to the loss of an internal segment. Even single deletions can cause abnormalities.
“Duplication” presence of a chromosomal segment more than once in the same chromosome.
“Inversion” is a segment 180 degree turn around, this reversal can then lead to altered gene activity such as deletions and duplications.
“Translocation” movement of chromosome segment from one chromosome to another no homologous chromosome. Downs Syndrome is sometimes caused by chromosome 21 being attached to chromosome 14 in the previous generation and can run in either the mother or father’s family gene pool.
Changes in the human chromosome structure lead to Syndromes that are just recently being studied. “Deletion Syndrome’ 8children have characteristics of pixie-ish looks, poor academic skills, however, excel in music and verbal skills. Skin ages prematurely and cardiovascular problems occur due to the protein elastin being missing in their bodies.”Cri du chat Syndrome” *Deletion syndrome where the end of chromosome 5 is missing. distinctive cry is like a cat, small head and mental retardation.
Chapter Nineteen, “Cancer”
19.1 Cancer Cells
Cancer accounts for more than 100 different diseases, however, there are some common characteristics that all types of cancer have.
Cancer is a cellular disease.
19.1 Cancer Cells
Cancer accounts for more than 100 different diseases, however, there are some common characteristics that all types of cancer have.
Cancer is a cellular disease.
Characteristics of cancer cells distinguish them from normal cells.
Cancer cells lack differentiation: they do not contribute to the bodies functioning.
Cancer cells DO NOT look like differentiated Epithelial (skin) Muscle, Nervous, or Connective tissue cells. Cancer cells look abnormal compared to all other cells.
Cancer cells have an abnormal nuclei. The abnormal nuclei is enlarged and may have an abnormal number of chromosomes.
Chromosomes of cancerous cells are also abnormal. When a healthy cell has damaged DNA then it goes through the process of Apoptosis (programmed cell death). Cancer cells fail to go through this cell death process.
Dividing tissues, such as respiratory and digestive tract lining tissues, are more likely to become cancerous. Because of cell division, the cells have more opportunity to undergo genetic mutation.
Cancer cells have unlimited replicative potential. Normal cells divide 60-70 times and then die but cancer cells can go on and on.
Cancer cells form tumors.
Cancer cells have no need for growth factors, which are signals between healthy cells telling the other to either grow (stimulatory) or to stop growing (inhibitory). Cancer cells continue to divide and reproduce.
Cancer cells gradually become abnormal. The development of cancer, known as Carcinogenesis,
Cancer cells lack differentiation: they do not contribute to the bodies functioning.
Cancer cells DO NOT look like differentiated Epithelial (skin) Muscle, Nervous, or Connective tissue cells. Cancer cells look abnormal compared to all other cells.
Cancer cells have an abnormal nuclei. The abnormal nuclei is enlarged and may have an abnormal number of chromosomes.
Chromosomes of cancerous cells are also abnormal. When a healthy cell has damaged DNA then it goes through the process of Apoptosis (programmed cell death). Cancer cells fail to go through this cell death process.
Dividing tissues, such as respiratory and digestive tract lining tissues, are more likely to become cancerous. Because of cell division, the cells have more opportunity to undergo genetic mutation.
Cancer cells have unlimited replicative potential. Normal cells divide 60-70 times and then die but cancer cells can go on and on.
Cancer cells form tumors.
Cancer cells have no need for growth factors, which are signals between healthy cells telling the other to either grow (stimulatory) or to stop growing (inhibitory). Cancer cells continue to divide and reproduce.
Cancer cells gradually become abnormal. The development of cancer, known as Carcinogenesis,
is multi-stage and broken into three phases;
(1) Initiation- single cell undergoes mutation
(2) Promotion- tumor develops
(3) Progression- one cell undergoes mutation that gives it selective advantage- Process is repeated several times, eventually there is a cell that can invade the surrounding tissues.
Cancer cells undergo Angiogenesis and Metastasis
Angiogenesis is the formulation of new blood vessels. To metastasize cancer cells must travel across the basement membrane and invade blood vessels or lymphatic vessels.
Invasive cancer cells are sperm shaped.
Cancer cells produce proteinase enzymes that degrade the membrane and allow them to invade the underlying tissues. Malignancy refers to the presence of cancer cells in nearby lymph nodes. When these cells begin new tumors from the primary tumor then Metastasis has occurred. Once Metastasis has occurred the probability of recovery for the individual is doubtful.
Cancer is genetic- The cell cycle occurs repeatedly because of mutation in two gene types when cancer is present.
(1)Proto-oncogenes/cause acceleration of the cell cycle-code for proteins that promote cell cycle and prevent apoptosis. Growth Factor means signal that activates cell signaling pathway, which results in cell division.
(2) Tumor-suppressor genes/ code for proteins that inhibit the cell cycle and promote apoptosis. When this type of gene mutates their products no longer inhibit the cell cycle. Retinoblastoma protein (RB) turns against the gene.
Oncology is the study of cancer- cancer is prevalent in society- one of three will deal with cancer in their lifetime.
Tumor classification is according to where in the body they originated. Carcinomas are cancers of epithelial tissues (skin cancer, breast, liver, pancreas, intestines, lung, prostrate, and thyroid. Adenocarcinomas are cancers of glandular epithelial cells.
Sarcomas are cancers of the muscles and connective tissue, like bone and fibrous connective tissue.
Leukemias are cancers of blood, Lymphomas are cancers of lymphatic tissue.
Lung cancer is common in the respiratory system. Colon/rectal cancer is common in the digestive system- also in the digestive system cancer family is pancreas, stomach, esophagus.
Cardiovascular system cancers are leukemia, plasma cell tumor. Lymphatic system cancers are either Hodgkin or Non-Hodgkin lymphoma. Thyroid cancer most common of the endocrine system. Brain and spinal tumors most common in the central nervous system.
Breast cancer is common and can be in either sex.
19.2 Causes and Prevention of Cancer
Heredity plays a large part in whether a person develops cancer. Genetic Profile refers to a person’s gene pool, which they received from their parents. Gene mutations that are inherited lead to cancer. Exposure to carcinogens in the environment play another large role in whether a person develops cancer or not. Environmental factors, Industrial chemicals, and viruses can be cancer causing.
19.3 Diagnosis of Cancer
The earlier a cancer is detected the better chance of recovery.
There are seven warning cancer signs.
Change in bowel or bladder habits.
A sore that does not heal.
Unusual bleeding or discharge.
Thickening or lump in breast or elsewhere.
Indigestion or difficulty in swallowing.
Obvious change in wart or mole.
Nagging cough or hoarseness.
Performing self-exams and then going in for Routine screening tests is one of the best ways to prevent and interrupt cancers.
Tumor marker tests are blood tests for tumor antigens/antibodies. These tests can detect a relapse in the genes after a person has had that type of cancer.
Tumor markers can also be used as an adjunct procedure to detect cancer in the first place.
19.4 Treatment of Cancer
Surgeries, radiation, and chemotherapy are standard treatments for cancers. Surgery to remove cancer is often followed by radiation to ensure there is no longer any live cancer. Ionizing radiation causes chromosomal breakage and cell cycle disruption. Cancer cells, because they are dividing cells, are more susceptible to the radiation than normal cells. There are negative side effects to receiving radiation. Radiation is a localized treatment. Most are temporary: diarrhea, irritated skin, fatigue, and weakness, sometimes hair loss , especially at the treatment site can be permanent.
Chemotherapy captures cancer cells that have already spread throughout the body. Chemotherapy treats the entire body. Chemo works by killing cells by damaging their DNA or interfering with DNA synthesis.
The chemicals used in chemotherapy are:
Alkylating Agents- interfere with the growth of cancer cells by blocking the replication of DNA.
Antimetabolites- block the enzymes needed by cancer cells to live and grow.
Antitumor Antibiotics- antibiotics that interfere with DNA.
Mitotic Inhibitors- inhibit cell division or hinder certain enzymes necessary in the cell reproduction process.
Nitrosoureas- impede enzymes that help repair DNA.
Bone marrow transplants are sometimes done in conjunction with chemotherapy.
Clinical trials are being evaluated on numerous types of therapies:
Immunotherapy- a vaccine called Melacine is currently being used to treat melanoma in studies. Genetically engineered immune genes are being tried and studied. Passive immunotherapy is also possible. P53 gene therapy expression is thought to be needed for 19 hours prior to cell death in cancer cells.
Cancers caused by tobacco products are one of the most preventable types of cancers. Smoking and the use of all tobacco products should be stopped and or never started. Tobacco companies market their products after the young population. Addiction to nicotine and other ingredients that are harmful in tobacco should be avoided at all costs.
Chapter 20, Patterns of Genetic Inheritance”
20.1 Genotype and Phenotype
Genotype refers to the genes of an individual. Alternative forms of a gene having the same position (locus) on a pair of chromosomes and affecting the same trait are called alleles.
Alleles occur in pairs, a person usually has two alleles for a trait. Example: EE= unattached earlobe ee=attached earlobe Ee- unattached earlobe. Alleles occur in the same location in the cell, it’s called the lotus.
Phenotype refers to the description of the characteristic.
Chapter 20, Patterns of Genetic Inheritance”
20.1 Genotype and Phenotype
Genotype refers to the genes of an individual. Alternative forms of a gene having the same position (locus) on a pair of chromosomes and affecting the same trait are called alleles.
Alleles occur in pairs, a person usually has two alleles for a trait. Example: EE= unattached earlobe ee=attached earlobe Ee- unattached earlobe. Alleles occur in the same location in the cell, it’s called the lotus.
Phenotype refers to the description of the characteristic.
20.2 One- and Two- Trait Inheritance
One trait crosses means that the inheritance of only one set of alleles is being considered and in two trait crosses the inheritance of two sets of alleles is being considered. In both scenarios it is necessary to determine the gametes of both individuals who are reproducing.
Forming the Gametes- during the process of gamesomeness the chromosome number is reduced. If this process did not happen each future generation would double in number their cell count. Reduction in chromosome number occurs when the homologous chromosomes separate during meiosis. The gametes carry only one (1) allele for each trait.
One trait crosses-
Step one- need to determine the genotype and then the gametes.
Individuals have two allele for every trait but gamete have one allele for every trait.
Step two- combine all possible sperm with all possible eggs/Punnett square may be helpful to determine ratio.
Monohybrid x monohybrid cross there is a 3:1 ratio expected among offspring.
Expected ratio converted to the chance of a particular genotype/phenotype.3:1= 75% chance of dominant phenotype and 25% chance of recessive phenotype.
Two Trait Crosses-
A cell has two pairs of homologous chromosomes. The homologous and the allele they carry, align independently during meiosis.
Dithered is when the individual is heterozygous in two regards. The 9:3;3:1 phenotypic is always expected for a dithered cross when simple dominance is present.
Two Trait Crosses and Probability-
The rules of probability can be used to predict the results of a dithered cross.
Family Pedigrees for Genetic Disorders-
When a genetic disorder is autosomal dominant, an individual with the alleles AA or Aa will have the disorder.
When a genetic disorder is autosomal recessive, only individuals with the allele aa will have the disorder. “Pedigrees” of genetic make up can determine whether a condition that runs in families is dominant or if it is recessive.
Auotosomal Recessive Disorder-parents are carriers because they appear to be normal but are capable of having a child with a genetic disorder.
Auotsomal Dominant Disorder- The child is unaffected but the parents are affected. When a disorder is dominant an affected child must have at least one affected parent.
Genetic Disorders of Interest- *single gene mutations
Tay-Sachs disease recessive disorder that usually occurs among Jewish people, appears normal till about 4-8 months, progressive deterioration of psychomotor functions, blindness, seizures, and paralysis.
Cystic Fibrosis-autosomal recessive disorder. It is the most common lethal genetic disorder for Caucasians in the United States- mucous forms in lungs and clogging of pancreatic ducts is common.
Phenylketonuria, sickle cell disease, marfan syndrome, and Huntington disease are some of the other more common genetic disorders.
One trait crosses means that the inheritance of only one set of alleles is being considered and in two trait crosses the inheritance of two sets of alleles is being considered. In both scenarios it is necessary to determine the gametes of both individuals who are reproducing.
Forming the Gametes- during the process of gamesomeness the chromosome number is reduced. If this process did not happen each future generation would double in number their cell count. Reduction in chromosome number occurs when the homologous chromosomes separate during meiosis. The gametes carry only one (1) allele for each trait.
One trait crosses-
Step one- need to determine the genotype and then the gametes.
Individuals have two allele for every trait but gamete have one allele for every trait.
Step two- combine all possible sperm with all possible eggs/Punnett square may be helpful to determine ratio.
Monohybrid x monohybrid cross there is a 3:1 ratio expected among offspring.
Expected ratio converted to the chance of a particular genotype/phenotype.3:1= 75% chance of dominant phenotype and 25% chance of recessive phenotype.
Two Trait Crosses-
A cell has two pairs of homologous chromosomes. The homologous and the allele they carry, align independently during meiosis.
Dithered is when the individual is heterozygous in two regards. The 9:3;3:1 phenotypic is always expected for a dithered cross when simple dominance is present.
Two Trait Crosses and Probability-
The rules of probability can be used to predict the results of a dithered cross.
Family Pedigrees for Genetic Disorders-
When a genetic disorder is autosomal dominant, an individual with the alleles AA or Aa will have the disorder.
When a genetic disorder is autosomal recessive, only individuals with the allele aa will have the disorder. “Pedigrees” of genetic make up can determine whether a condition that runs in families is dominant or if it is recessive.
Auotosomal Recessive Disorder-parents are carriers because they appear to be normal but are capable of having a child with a genetic disorder.
Auotsomal Dominant Disorder- The child is unaffected but the parents are affected. When a disorder is dominant an affected child must have at least one affected parent.
Genetic Disorders of Interest- *single gene mutations
Tay-Sachs disease recessive disorder that usually occurs among Jewish people, appears normal till about 4-8 months, progressive deterioration of psychomotor functions, blindness, seizures, and paralysis.
Cystic Fibrosis-autosomal recessive disorder. It is the most common lethal genetic disorder for Caucasians in the United States- mucous forms in lungs and clogging of pancreatic ducts is common.
Phenylketonuria, sickle cell disease, marfan syndrome, and Huntington disease are some of the other more common genetic disorders.
20.3 Beyond Simple Inheritance Patterns-
In some patterns of inheritance the alleles are not just dominant or recessive.
The dominant allele have a quantities effect on the phenotype, and the effects are additive. Continuous variation is the result.
The more genes that are involved, the more continuous the variations and distribution of the phenotypes.
Skin color is an example of a polygenic likely to be controlled by many pairs of alleles.
Multifactorial traits- polygenic trait that is particularly influenced by the environment.
Multifactorial Disorders- it is believed that numerous human disorders controlled by polygenes that are subject to environmental influences. In recent years reports have surfaced that behavioral traits in humans can be associated with particular genes. So far it has not been possible to determine to what degree this report is true.
Incomplete dominance is when the heterozygote is intermediate between the two homozygotes.
Codominance occurs when alleles are equally expressed in a heterozygote. The prognosis in familial hypercholesterolemia parallels the number of LDL cholesterol receptor proteins in the plasma membrane.
Multiple Allele Inheritance- a trait is controlled by multiple alleles the gene exists in several allelic forms.
20.4 Sex-Linked Inheritance
Most sex linked disorders are carried on the X chromosome. Many of the X chromosome genes are not related to the gender of the individual.
22 pairs of human genes are called autosomes and one pair is called the sex chromosomes. Traits that are controlled on the sex chromosomes are ‘sex linked”.
Few known traits are X- linked dominant- if so the affected male passes the trait only to daughters. Recessive alleles on the X chromosome are always expressed in males. Y chromosome lacks an allele for disorder.
X linked Recessive disorders- color blindness, affects approximately 8% of male population- does not interfere with normal life activities. Other disorders: muscular dystrophy, hemophilia.
Pros and Cons for Genetic Profiling; Genetic profiling data and access to the information would be helpful in the prevention of illnesses. If the individual who was genetically linked to a specific disease took precautionary measure in their life prior to the disease onset, would it delay or prevent the disease from occurring? If genetic profiling information was readily available to the public, would the information be used against specific individuals because of genetic weaknesses or predisposition to disease?
In some patterns of inheritance the alleles are not just dominant or recessive.
The dominant allele have a quantities effect on the phenotype, and the effects are additive. Continuous variation is the result.
The more genes that are involved, the more continuous the variations and distribution of the phenotypes.
Skin color is an example of a polygenic likely to be controlled by many pairs of alleles.
Multifactorial traits- polygenic trait that is particularly influenced by the environment.
Multifactorial Disorders- it is believed that numerous human disorders controlled by polygenes that are subject to environmental influences. In recent years reports have surfaced that behavioral traits in humans can be associated with particular genes. So far it has not been possible to determine to what degree this report is true.
Incomplete dominance is when the heterozygote is intermediate between the two homozygotes.
Codominance occurs when alleles are equally expressed in a heterozygote. The prognosis in familial hypercholesterolemia parallels the number of LDL cholesterol receptor proteins in the plasma membrane.
Multiple Allele Inheritance- a trait is controlled by multiple alleles the gene exists in several allelic forms.
20.4 Sex-Linked Inheritance
Most sex linked disorders are carried on the X chromosome. Many of the X chromosome genes are not related to the gender of the individual.
22 pairs of human genes are called autosomes and one pair is called the sex chromosomes. Traits that are controlled on the sex chromosomes are ‘sex linked”.
Few known traits are X- linked dominant- if so the affected male passes the trait only to daughters. Recessive alleles on the X chromosome are always expressed in males. Y chromosome lacks an allele for disorder.
X linked Recessive disorders- color blindness, affects approximately 8% of male population- does not interfere with normal life activities. Other disorders: muscular dystrophy, hemophilia.
Pros and Cons for Genetic Profiling; Genetic profiling data and access to the information would be helpful in the prevention of illnesses. If the individual who was genetically linked to a specific disease took precautionary measure in their life prior to the disease onset, would it delay or prevent the disease from occurring? If genetic profiling information was readily available to the public, would the information be used against specific individuals because of genetic weaknesses or predisposition to disease?
Chapter 21, “DNA Biology and Technology”
21.1 DNA and RNA Structure and Function
DNA is genetic material that is mostly found in the chromosomes, located in the cell’s nucleus.
Genetic material must be able to do these three things:
(1) replicate so it can be transmitted to next generation
(2) store information
(3) undergo mutations that provide genetic variability
21.1 DNA and RNA Structure and Function
DNA is genetic material that is mostly found in the chromosomes, located in the cell’s nucleus.
Genetic material must be able to do these three things:
(1) replicate so it can be transmitted to next generation
(2) store information
(3) undergo mutations that provide genetic variability
DNA is a “Double Helix”- composed of two strands that spiral about each other- each of the strands is a polynucleotide because it is composed of a series of nucleotides. A nucleotide is a molecule composed of three (3) sub-units, which are, (1) phosphoric acid (2) pentose sugar (3) nitrogen-containing base.
Study the DNA double Helix:
In one strand of DNA the phosphates (P) and sugar molecules (S) make a “backbone” and that the bases project to one side. Put the two strands together and the DNA resembles a ladder.
The phosphate (P) and sugar (S) backbones make the side supports of a ladder and the “rungs (cross bars) are composed of PAIRED bases.
The bases are held together by hydrogen bonding.
Complementary paired bases means that “A” pairs with “T” by forming two (2) hydrogen bonds, and “G” pairs with “C” by forming three (3) hydrogen bonds, or vice versa.
Bases are very important to DNA function. A purine base has two rings and is always paired with a pyrimidine base, which has one ring.
The two strands of DNA are anti-parallel (run in opposite directions)
DNA Replication- during cell division, each new cell gets an EXACT copy of DNA. Process of copying a DNA helix is called “DNA Replication”.
During replication the double stranded structure of DNA allows each original strand to serve as a template for formation of a complementary new strand.
DNA is called “Semiconservative’ because EACH new Double Helix has one ORIGINAL strand and one new strand. (One original strand is “conserved”) Ther are now two DNA helixes identical to each other and to the originsl molecule.
Study the DNA double Helix:
In one strand of DNA the phosphates (P) and sugar molecules (S) make a “backbone” and that the bases project to one side. Put the two strands together and the DNA resembles a ladder.
The phosphate (P) and sugar (S) backbones make the side supports of a ladder and the “rungs (cross bars) are composed of PAIRED bases.
The bases are held together by hydrogen bonding.
Complementary paired bases means that “A” pairs with “T” by forming two (2) hydrogen bonds, and “G” pairs with “C” by forming three (3) hydrogen bonds, or vice versa.
Bases are very important to DNA function. A purine base has two rings and is always paired with a pyrimidine base, which has one ring.
The two strands of DNA are anti-parallel (run in opposite directions)
DNA Replication- during cell division, each new cell gets an EXACT copy of DNA. Process of copying a DNA helix is called “DNA Replication”.
During replication the double stranded structure of DNA allows each original strand to serve as a template for formation of a complementary new strand.
DNA is called “Semiconservative’ because EACH new Double Helix has one ORIGINAL strand and one new strand. (One original strand is “conserved”) Ther are now two DNA helixes identical to each other and to the originsl molecule.
The step process of replication:
(1) “The two strands that make up parental DNA are hydrogen- bonded together.
(2) An enzyme unwinds and un-zips double stranded DNA. This means that the weak hydrogen bonds between the paired bases break.)
(3) The new complementary DNA nucleotides present in nucleus and fit into place by process of complementary base pairing. The enzyme “DNA polymerase” positions and joins the new strands together.
(4) Replication is completed when an enzyme seals the breaks in the sugar-phosphate backbone.”
The end product of this entire process:
Two double helix molecules are identical to each other and to the original molecule.
Very rarely there is a replication error in the sequence of DNA parental strand. When this occurs the cell uses repair enzymes that usually fix the error. When repair does not occur then it is called a Mutation. This ‘mutation” means a permanent change in the sequence of bases that could lead to change in the phenotype and introduce variability. These variability’s make everyone and everything different.
The structure and function of RNA-
RNA is composed of nucleotides containing the sugar ribose.
RNA is single stranded-Remember, DNA is double stranded.
Sometimes the single strand RNA doubles back on itself. Complementary base-pairing still occurs.
(1) “The two strands that make up parental DNA are hydrogen- bonded together.
(2) An enzyme unwinds and un-zips double stranded DNA. This means that the weak hydrogen bonds between the paired bases break.)
(3) The new complementary DNA nucleotides present in nucleus and fit into place by process of complementary base pairing. The enzyme “DNA polymerase” positions and joins the new strands together.
(4) Replication is completed when an enzyme seals the breaks in the sugar-phosphate backbone.”
The end product of this entire process:
Two double helix molecules are identical to each other and to the original molecule.
Very rarely there is a replication error in the sequence of DNA parental strand. When this occurs the cell uses repair enzymes that usually fix the error. When repair does not occur then it is called a Mutation. This ‘mutation” means a permanent change in the sequence of bases that could lead to change in the phenotype and introduce variability. These variability’s make everyone and everything different.
The structure and function of RNA-
RNA is composed of nucleotides containing the sugar ribose.
RNA is single stranded-Remember, DNA is double stranded.
Sometimes the single strand RNA doubles back on itself. Complementary base-pairing still occurs.
DNA-RNA similarities-
Both are nucleic acids
Both are composed of nucleotides
Both have a sugar-phosphate backbone
Both have four different types of base
DNA-RNA differences-
DNA is found in nucleus/RNA found in nucleus and cytoplasm.
DNA is a genetic material/RNA is a helper to DNA
DNA sugar is deoxyribose/RNA sugar is ribose
DNA bases are A,T,C,G/RNA bases are A,U,C,G
DNA is double stranded/RNA is single stranded
DNA is transcribed (to give Mrna)/RNA is translated (to give proteins)
Messenger RNA ( m RNA )is produced in the nucleus where DNA serves as a template for its formation. * carries genetic information from DNA to the ribosomes in the cytoplasm where protein synthesis occurs.
Transfer RNA (t RNA) is produced in the nucleus and a portion of DNA also serves as a template for its production. * transfers amino acids to the ribosomes where the amino acids are joined, forming a protein.
21.2 Gene Expression
Gene expression requires transcription and translation.
Protein structure is the sequence of its amino acids- the secondary structure can be a helix or pleated sheet- the tertiary structure is the final three-dimensional shape of the protein structure.
During transcription 9step one) segment of DNA serves as template for production of RNA molecule. *m RNA is a class of RNA.
The enzyme RNA polymerase opens up the DNA helix just in front so Complementary base -pairing can occur. Next RNA polymerase joins RNA nucleotides and m RNA molecules result. Then m RNA forms and has sequence of bases complementary to DNA. Wherever there is A,T,G,C present in DNA template then U,A,C,G is incorporated into the m RNA molecule. Now m RNA is a copy of sequence of bases in DNA.
Processing m RNA- after transcription then it must be processed.
Translation occurs in cytoplasm at the ribosomes.
Regulation occurs at four levels.
(1) transcriptional control- degree a gene is transcribed into m RNA determines amount of gene product. (In nucleus)
(2) post-transcriptional control- involves m RNA processing. (In nucleus)
(3) translational control- affects when translation starts and how long it lasts (in cytoplasm)
(4) post-translational control- occurs after protein synthesis (in cytoplasm)
21.3 Genomics
Some medical conditions can be treated with gene therapies.
Gene therapy involves the insertion of genetic material into human cells for treatment of a disorder.
Ex Vivo Gene Therapy- and In Vivo Gene Therapy are two types.
Functional genomic is the study of genes and how they operate/work. Comparison of genomes can tell how species have evolved. Genomes has discovered that all vertebrates are very similar.
Proteomics is the study of the structure, function, and interaction of cellular proteins. Translation of all coding genes results in collection of proteins called the human proteome.
Bioinformatics is the application of computer technologies to the study of genome.
21.4 DNA Technology
Genes can be isolated and cloned. Cloning is the production of genetically identical copies of DNA, cells, or organisms through asexual means.
Gene Cloning produces many identical copies of the same gene.
Recombinant DNA contains DNA from two or more different sources.
1- restriction enzyme used to cleave human DNA and plasmid DNA.
2-DNA enzyme called “DNA ligase” used to seal foreign DNA.
3- bacterial cells take up a recombinant plasmid.
4a-gene cloning occurs as the plasmid replicates on its own.
4b-bacterium is also transformed and can make a product * such as insulin, that it could not make before.
Polymerase chain re-action (PCR) can create copies of a segment of DNA quickly in a test tube.
PCR requires using DNA polymerase.
The DNA amplified by PCR is often analyzed for various purposes.After PCR, then DNA Cn be subjected to DNA fingerprinting.
DNA fingerprinting can be used to find the presence of viral infections, genetic disorders, and cancers. If the DNA matches that of a virus or mutation then the disorder is present.
Bacteria, plants, and animals are genetically engineered to produce biotechnology products. Transgenetic Organisms are those that have had a foreign gene inserted into them.
Biotechnology products are produced , such as, hormones and vaccines.
Transgenetic bacteria is helpful in promotion of plant health, removing sulfur from coal, and mineral extraction.
Transgenic crops resist herbicides and pests. Transgenic Animals can be given Growth Hormone to produce larger offspring, can supply transplant organs, and produce pharmaceuticals.
My Final Thoughts on what I have learned.
Both are nucleic acids
Both are composed of nucleotides
Both have a sugar-phosphate backbone
Both have four different types of base
DNA-RNA differences-
DNA is found in nucleus/RNA found in nucleus and cytoplasm.
DNA is a genetic material/RNA is a helper to DNA
DNA sugar is deoxyribose/RNA sugar is ribose
DNA bases are A,T,C,G/RNA bases are A,U,C,G
DNA is double stranded/RNA is single stranded
DNA is transcribed (to give Mrna)/RNA is translated (to give proteins)
Messenger RNA ( m RNA )is produced in the nucleus where DNA serves as a template for its formation. * carries genetic information from DNA to the ribosomes in the cytoplasm where protein synthesis occurs.
Transfer RNA (t RNA) is produced in the nucleus and a portion of DNA also serves as a template for its production. * transfers amino acids to the ribosomes where the amino acids are joined, forming a protein.
21.2 Gene Expression
Gene expression requires transcription and translation.
Protein structure is the sequence of its amino acids- the secondary structure can be a helix or pleated sheet- the tertiary structure is the final three-dimensional shape of the protein structure.
During transcription 9step one) segment of DNA serves as template for production of RNA molecule. *m RNA is a class of RNA.
The enzyme RNA polymerase opens up the DNA helix just in front so Complementary base -pairing can occur. Next RNA polymerase joins RNA nucleotides and m RNA molecules result. Then m RNA forms and has sequence of bases complementary to DNA. Wherever there is A,T,G,C present in DNA template then U,A,C,G is incorporated into the m RNA molecule. Now m RNA is a copy of sequence of bases in DNA.
Processing m RNA- after transcription then it must be processed.
Translation occurs in cytoplasm at the ribosomes.
Regulation occurs at four levels.
(1) transcriptional control- degree a gene is transcribed into m RNA determines amount of gene product. (In nucleus)
(2) post-transcriptional control- involves m RNA processing. (In nucleus)
(3) translational control- affects when translation starts and how long it lasts (in cytoplasm)
(4) post-translational control- occurs after protein synthesis (in cytoplasm)
21.3 Genomics
Some medical conditions can be treated with gene therapies.
Gene therapy involves the insertion of genetic material into human cells for treatment of a disorder.
Ex Vivo Gene Therapy- and In Vivo Gene Therapy are two types.
Functional genomic is the study of genes and how they operate/work. Comparison of genomes can tell how species have evolved. Genomes has discovered that all vertebrates are very similar.
Proteomics is the study of the structure, function, and interaction of cellular proteins. Translation of all coding genes results in collection of proteins called the human proteome.
Bioinformatics is the application of computer technologies to the study of genome.
21.4 DNA Technology
Genes can be isolated and cloned. Cloning is the production of genetically identical copies of DNA, cells, or organisms through asexual means.
Gene Cloning produces many identical copies of the same gene.
Recombinant DNA contains DNA from two or more different sources.
1- restriction enzyme used to cleave human DNA and plasmid DNA.
2-DNA enzyme called “DNA ligase” used to seal foreign DNA.
3- bacterial cells take up a recombinant plasmid.
4a-gene cloning occurs as the plasmid replicates on its own.
4b-bacterium is also transformed and can make a product * such as insulin, that it could not make before.
Polymerase chain re-action (PCR) can create copies of a segment of DNA quickly in a test tube.
PCR requires using DNA polymerase.
The DNA amplified by PCR is often analyzed for various purposes.After PCR, then DNA Cn be subjected to DNA fingerprinting.
DNA fingerprinting can be used to find the presence of viral infections, genetic disorders, and cancers. If the DNA matches that of a virus or mutation then the disorder is present.
Bacteria, plants, and animals are genetically engineered to produce biotechnology products. Transgenetic Organisms are those that have had a foreign gene inserted into them.
Biotechnology products are produced , such as, hormones and vaccines.
Transgenetic bacteria is helpful in promotion of plant health, removing sulfur from coal, and mineral extraction.
Transgenic crops resist herbicides and pests. Transgenic Animals can be given Growth Hormone to produce larger offspring, can supply transplant organs, and produce pharmaceuticals.
My Final Thoughts on what I have learned.
DNA and cell replication is a complicated process! The most interesting chapter I found was chapter 19 on cancer. I lost my Mother to cancer, lung, stomach, and liver cancer, 15 years ago. Her diseases were definitely caused, and or influenced by environmental choices and factors. Two years ago , my 13 year old nephew developed osteo sarcoma, and in a matter of 2 1/2 months his leg needed to be amputated as well as he had to have double lung surgery, which removed 71 nodules of cancer. He is currently doing exceptionally well and although the long run prognosis isn't the grandest , he has certainly beat statistics so far!! He is 15 years old, in 10th grade, rides his bike, working toward his permit, and loves to boat and jet ski. It's hard for me to think back at how AGRESSIVE the cancer was in his body. Chapter 19 explained alot I didn't know before so it all makes a little more sense, even though I still despise cancer and what it can do to a person.
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