Download DNA

Name:
3-31-08
Honors Biology
Ms. Thaler
DNA Websites:
Discovery, Structure, and Replication!
Part A. Go to http://www.dnaftb.org/dnaftb/15/concept/
Or Google “DNA” click go to www.dnaftb.org/dnaftb and select the “Molecules of Genetics.”
Note the right side menu and that you are starting on number 15. First read the concept
paragraph and answer the following questions.
1. Before DNA was found to be the molecule of inheritance, what did most scientists
believed contained the “code of life”?
2. What made DNA an unlikely candidate to control the organism’s structure?
. Now follow the animation from the bottom menu
3. Who was Friedrich Mieshcher? What did he study? What did he find?
4. What did he call the unique chemical substance that he isolated? What did he believe its
function was?
5. How many different amino acids make up proteins?
6. Why did Phoebus Levene think that proteins would make a good candidate for the
molecule of heredity?
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Name:
3-31-08
7. What are the 3 main elements of a nucleotide?
Honors Biology
Ms. Thaler
______________________________
______________________________
Backbone
______________________________
8.
List the 4 different nucleotides:
______________________________
______________________________
______________________________
______________________________
9. Draw a nucleotide.
10. What is a phosphodiester bond?
11. Bonus: With a sequence of 4 different nucleotides, how many different combinations are
possible? (NOTE: This is a mathematical problem that you can figure out using
permutations, i.e. how many different combinations are there with 4 letters if each letter
can be used as many as four times per combination ex. CCCC or CCGG, etc)
Part B: Now go to http://gslc.genetics.utah.edu/units/basics (Google “learn genetics”)
Select “What is DNA?” from the menu
You can also follow the animations for “What is a gene?” and “What is a chromosome?”
12. When you look at the DNA helix can you see the how the bases are bonded to each
other by hydrogen bonds? Can you see a difference in the number of hydrogen bonds?
Explain what you see.
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3-31-08
13. What does a gene tell the cell to make?
Honors Biology
Ms. Thaler
14. What is a chromosome?
Part C: Now try to look at a more advanced model of DNA at
http://www.johnkyrk.com/DNAanatomy.html
Use the small arrow on the bottom left of the display to go through the animation (you
can also toggle between the backbone and code with the switches on the bottom
left)
15. What does 3’ and 5’ refer to? What does it mean that the strands of DNA are
antiparallel?
16. What is the “backbone” and what is the “code”? Why are they described in these terms?
17. How many base pairs are in the human genome?
Part D: Now go to back to http://www.dnaftb.org/dnaftb/29/concept/, read the concept
paragraph.
18. Chromosomes are composed of __________ and ____________.
19. What are histones?
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Name:
3-31-08
Honors Biology
Ms. Thaler
20. What is the difference between chromatin and chromosomes?
Under Gene Organization and Control on the right side menu, and go to 30 “Higher cells
incorporate an ancient chromosome.”
21. What organelles also have chromosomes/DNA besides the nucleus?
Select the animation and follow it through by clicking on the right arrow:
22. How are bacteria different from plant and animal cells? What are these types of cells
called?
DNA Replication
Part E: Go to http://www.pbs.org/wgbh/aso/tryit/dna/index.html# and click on the first bullet,
which saya “DNA workshop activity.” When the box comes up, click on “DNA replication” to the
left of the helix. View the animation and answer the questions.
23. What has to happen to the double helix before it can “un-zip”?
24. What bonds break when the molecule un-zips?
25. Match up the new nucleotides by complementary base pairs. Wasn’t that fun?
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Name:
Honors Biology
3-31-08
Ms. Thaler
Part F: Go to http://highered.mcgrawhill.com/sites/0072437316/student_view0/chapter14/animations.html# and click on the first link
called “ How Nucleotides are Added in DNA Replication (1028.0K)” to see a more
detailed example of DNA replication.
26. Where does replication begin?
27. What comes in to begin replication? (What’s that purple blob?)
28. The rest of this video shows some of the complexities of the replication process. What
are some of the things that you notice? Don’t freak out, just make a few observations.
Part G: Go to http://www.johnkyrk.com/DNAreplication.html to see another complex animation
of DNA synthesis.
29. “An exact copy of DNA must be created prior to ____________. Any errors represent
______________________.”
30. What does the “bubble” refer to? Describe it.
Part H: Here are some other animations you might want to check out that show DNA replication:
http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swf
http://www.fed.cuhk.edu.hk/~johnson/teaching/genetics/animations/dna_replication.htm
(over)
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Name:
3-31-08
Honors Biology
Ms. Thaler
31. Draw a helicase splitting a DNA double helix. Label the helicase and the replication fork.
32. Draw nucleotides attaching to both sides of the split helix with a DNA polymerase. Show
the complimentary base pairs (As, Ts, Gs, and Cs).
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