Download DNA STRUCTURE (Sections 10.1 – 10.3)

AP Biology Reading Guide for Chapter 10
Molecular Biology of the Gene
This chapter has a LOT of information. In order to understand, learn, and remember all this information (and
there's a lot), you'll need to get all you can out of class, and supplement it with both the review and the new material
found in this Reading Guide. (Did I mention there is a LOT of information? Don't worry – this is fascinating stuff!)
Bring this guide with you on the assigned day, along with any questions you still have about it.
DNA STRUCTURE (Sections 10.1 – 10.3)
Use the video at http://www.youtube.com/watch?v=qoERVSWKmGk to help answer these questions:
1. What did Griffith discover?
2. What did Avery et al do with this discovery?
3. What did Hershey and Chase then do? (the “blender” experiment)
4. All good students of biology should know the names of the two guys who created the double helix
model of DNA – who are they?
5. What are the names of the other two people who were instrumental in this discovery, though they didn’t
initially receive credit?
6. Describe Chargaff’s rule.
7. Label as many parts of the diagrams below as you can:
8. Why does adenine always pair with thymine and guanine with cytosine in DNA?
9. Which bases are the purines? The pyrimidines? (Include all 5 nucleotides)
10. What is meant by the term that DNA replication is semiconservative?
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In this next section, the questions don’t necessarily come in order. You will need to read, re-read, back
up, look ahead, check out the diagrams, read again, puzzle over it. . . that’s science for you!
Use the video at http://www.youtube.com/watch?v=W4mYwsr9gGE to help illustrate what’s in the text.
DNA REPLICATION -The Parts
1. First, the two strands of DNA have to separate. This occurs at an origin of replication. Bacterial
chromosomes have one of these, while eukaryotic cells have numerous origins, which speeds up the
process considerably. Look at Figure 10.5A to see how replication bubbles are formed and join. What is
a replication fork?
2. What is meant by each of these:
• antiparallel
• 5’ and 3’
• leading strand
• lagging strand
• Okazaki fragment
3. What role do each of these enzymes have in the process of DNA replication? (not all of these are in
your text)
• DNA polymerase (I and III)
• helicase
• single strand binding proteins
• primase
• ligase
4. Recall this process from class and label as much of it as you can:
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5. What’s happening in this diagram? Where is it occurring? Label as many parts as you can:
DNA REPLICATION - The Process
1. Which end of a newly growing DNA strand does DNA polymerase add new nucleotides to? _______
2. Why can’t both DNA polymerases go in the same direction (ie, following along right behind the helicase
enzyme?
3. How does the replication process overcome this problem?
4. When the two sides of DNA separate, what has to happen to the newly exposed DNA strand before the
DNA polymerase can add DNA nucleotides to it?
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5. What are telomeres and why are they important? How does telomerase play a role?
PROTEIN SYNTHESIS
Background:
1. The code itself is based on a set of ________ nucleotides, or codons (DNA or mRNA).
(a number)
2. The process of protein synthesis occurs in two parts: _________________________ (in the nucleus)
and ____________________________ (in the cytoplasm, on a ribosome).
3. In one sentence, describe transcription.
4. In one sentence, describe translation.
5. Use Figure 10.8A to determine the amino acids coded for by these mRNA codons:
CCU –
AGU –
Transcription ( we’ll look at this and at translation in detail during class.)
1. Where does transcription take place in a eukaryotic cell? How about in a prokaryotic cell?
2. What are the three stages of transcription?
3. Unlike DNA replication, in protein synthesis only a small section of the DNA is actually used to make a
protein. How does the RNA polymerase know where on the DNA strand to start and stop?
6. Use the diagram below to understand transcription: Define all terms.
4. In which direction does elongation occur?
5. What does mRNA stand for? ______________________________________
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6. Look ahead to section 10.10. Before mRNA can be translated at the ribosome, it must be processed.
Describe three things that have to happen to it.
7. See if you can find out what might be found in the introns. Would you consider introns to be “junk
DNA”? Why or why not?
Translation
1. What is a tRNA, and what is its codon called?
2. How does the tRNA pick up its specific amino acid?
3. What does it then do with this amino acid?
4. How does the structure of the ribosome facilitate this?
5. Describe the structure and function on ribosomal RNA – use the diagram below.
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6. Label the diagram below and use it to explain elongation cycle of translation.
7. Use the diagram below to detail the termination of translation – define all terms.
8. List the start and stop codons: ___________ Start ________________________________Stop
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Mutations (within a gene, often called point mutations)
1. Define the following terms:
a. Mutations
b. Mutagen
c.
Base pair substitution
d. Missense
e. Nonsense
f.
Insertions
g. Deletions
h. Frameshift mutation
2. What is meant by the “reading frame”?
3. With regards to the reading frame, which mutation is more likely to be damaging – substitution or
insertion, and why?
VIRAL REPLICATION
1. Viruses aren’t exactly cells. . . so, what ARE they?
2. What is the relationship between viruses, bacteriophages, and phages?
3. Summarize the five steps of the lytic cycle. We won’t go over these in class, unless you have specific
questions.
4. Summarize the major difference between the lysogenic and the lytic cycles. Again, we won’t go over
this in class unless there are questions.
5. What is a:
retrovirus –
reverse transcriptase –
vaccine –
8. Why are antibiotics useless against viruses?
BACTERIAL REPLICATION
1. Describe what a bacterial chromosome looks like. How is it similar to ours? Different?
2. How is bacterial DNA replication accomplished?
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Recall that a bacterium’s genome is found in a single loop of DNA. Bacteria reproduce their numbers by
doing binary fission (splitting in two). Since this just creates clones of the original, how do bacteria gain
genetic mutations and evolve?
1. Glad you asked. . . there are three main ways: (briefly summarize each)
a. Transformation –
b. Transduction –
c. Conjugation (no, NOT Latin verbs!) –
2. Once the new DNA is inside a bacterial cell, how does it get ingetrated?
3. What are plasmids? How are they useful?
Keep going. . . there’s a lovely summary diagram of protein synthesis on the next page
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Use this diagram of protein synthesis to help you study the “whole” picture. SUGGESTION: Label all
parts, and describe the processes of Transcription, mRNA processing, and Translation.
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