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Embed code for: problem set 2 w14- DNA
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B BIO 200: Introductory Biology 2 Name: ___________________________
Problem Set 2
due Thursday Feb 20, 2014
1. Below is a portion of double stranded DNA from a bacterial chromosome that contains a
gene. The promoter region and the +1 base pair are indicated, as well as the polarity of the
two DNA strands.
+1 -10 -35
The top strand is the template strand
a. What are the first six bases of the transcribed mRNA? Indicate the 5’ and 3’ ends.
b. What are the first three amino acids of the protein encoded? [2 pts]
Indicate the N-terminal end of this set of three amino acids.
c. The first part of the mRNA is not the coding region…what is it and why is it important. [2pts]2. The diagram below shows a DNA replication bubble in a salmon cell. The circles indicate the origin
of replication.The four letters (A, B, C, D) show where new DNA strands are being synthesized.
a. For each of the four letters, indicate whether the DNA being made there is
a leading strand or a lagging strand. [4 pts]
A: __________________ B: _________________
C: __________________ D: _________________
b. Draw one leading strand on the diagram, indicating the RNA primer, 5’ and 3’ ends [2 pts]
c. If you add a chemical that inhibits the enzyme DNA ligase, which strand(s) (A, B, C, D) would be
most affected? Why? [2 pt]
3. The DNA sequence of a short gene from a sea slug, and the mature RNA synthesized from this
gene, are shown below.
5’ - AGCATCTCATGTGCGAGTCCTGACGCTGACTAGC – 3’
3’ - TCGTAGAGTACACGCTCAGGACTGCGACTGATCG – 5’
5’ – cap-AUCUCAUGUGCGAACGCUGACUAGAAAAAAAAAA- 3’
a. In the DNA sequence, draw boxes around two exons in the gene. [2 pts]
b. Draw boxes around any structures or bases that were added to the RNA during processing.
c. How many amino acids are in the peptide encoded by the gene? [1 pt]