UP #4: DNA / Mutation
With selected student responses
QUESTION 1: DNA is a double-stranded molecule, meaning that each DNA molecule contains two strands of DNA running in opposite directions. Why do you think it is advantageous for the cell to maintain DNA as a double stranded molecule rather than a single-stranded molecule?
From RB: Q1 = So that if one side is damaged the other is still intact and undamaged. The undamaged side of the DNA can then attach to another half strand and not be changed. Another reason that I believe may be advantageous for the double strand is for when the cell replicates its self. One half of the DNA goes to one side and the other to the opposite side.
From HT Q1 = It is important for a dna a strand to have 2 strands instead of one because dna needs to replicate itself and in order to do that the 2 strands need to come apart. If it only had one strand then it would not be able to replicate.
From Altman Q1 = It's like putting all of your eggs in one basket if you have only one strand. With two strands, one can break and the necesary information to repair it or do cell work is still contained within the cell. Also, reproduction is quicker and easier with two strands because the initial process of replication is done.
From PP Q1 = They can check each other at various points. If something is wrong with one, then the other can have an effect on correcting it.
From Elizabeth: Q1 = I think that it is more advantagouse to have a double stranded molecule because the strong covalent bonds hold the genetic material (the rungs of the ladder) together better than just having one strand.
From Amy Q1 = I think it is easier for a cell to maintain DNA as a double stranded molecule rather than a single-stranded molecule because the adenine and cytosine, have the thymine and the guanine to hang on to possibly making the molecule stronger.
QUESTION 2: QUESTION 2:
What happens if DNA is damaged? Do you think that this is
something that occurs a lot in our cells, or only infrequently?
What do you think are some things in the environment that cause
damage and changes (mutations) in DNA?
MercuryQ2 = If DNA is damaged it could cause different kinds of birth defects. Some things in our enviroment that could mutate DNA are probably different kinds of pollutants in the water or air. Also some kinds of medication could cause mutations in unborn babies. Animals that drink polluted water or eat plants with DDT or different kinds of pestisides could have offspring with mutated DNA.
LF Q2 = Although I am not sure how frequently or infrequently this may occur, I think if our DNA is damaged then it cannot replicate itself properly and dies, (spontaneous abortion). If it does not die, then someone may be born with a certain genetic condition. Some things that can cause damage and changes in DNA, I think could be pesticides, medications, or possible eating diseased fish from the "White River". haha
From hjc: Q2 = I think if DNA is damaged it may cause disease, disformations, etc. Environmental factors that may be damaging to DNA may include chemicals, radiation, asbestos, or anything else scientists haven't yet discovered that is damaging to our cells.
From caadavid Q2 = If there is damaged DNA, there would probably be something wrong with the baby or the formation of the life. I am sure that it happens more frequently then we think. Chemicals that we come in contact with could cause damages.
Mo Q2 = If DNA is damaged than the cell contains a disease. Cancer is a disease that is more common in humans than it ever was.
QUESTION 3: Rosalind
Franklin collected X-ray data crucial to the discovery of DNA's
structure. However, she is hardly mentioned in some accounts of
the discovery of DNA. Your textbook presents a short essay about
the discovery of the structure of DNA (p. 149-150); read it and
speculate why she might be less well known than Watson and Crick.
Why was she not awarded a Nobel Prize in 1962 with Watson and
From Jenn: Q3 = Franklin was extremely meticulous in her work and took her time to observe DNA. Watson and Crick saw an opportunity to become famous (so it sounds to me) and deviously took x-ray photos from Franklin and took it from there working a little faster than Franklin and weren't afraid to come to conclusions and beat her to fame by discovering the helix in DNA.
From Stitches Q3 = Rosalind Franklin died of cancer in 1958. The Nobel Prize is not awarded posthumously.
From Monkey Q3 = Rosalind Franklin's work was unfinished and she did not want to jump to conclusions until she had enough data to support her findings. Her x-ray's were stolen by her colleagues adn they went on to publish her information, and became known as the ones who discovered the structure of DNA. Franklin died of cancer before the Nobel Prize was awarded, therefore deprived of her well-earned reward.
QUESTION 4: Totally Optional: Comments on the exam?
Q4 = I felt the matching sections on the test to
be very difficult.
Q4 = I thought the test was hard. I think we need more review time in class
Q4 = The test was not what I expected at all.
Q4 = Oh My!
Q4 = The exam really tested how much an individual could retain.
Q4 = I liked the test! : )
Q4 = I need to study more.
Q4 = I wish I could take it over.
Q4 = The exam was a little more challenging than I expected. I enjoyed it!
Q4 = The study guide and the practice test really helped.