Bio 201 Spring 2014
Chapter 8 Part 1 Homework
Name:____________________________
Use the following DNA sequence and information to answer questions 1-10. (5 points each, 50
points total)
3’ ACAGGTCGGCAATTG 5’
5’ TGTCCAGCCGTTAAC 3’
Assume three things:
A) transcription and translation are going from left to right
B) a promoter for the RNA polymerase is upstream of this section of DNA and pointing right
C) a ribosome biding site and a start codon are upstream also and not pictured
1. Which strand is the template for transcription? (top, bottom, or both)
top
2. What is the mRNA sequence? (Label 5’ and 3’ also)
5’ UGUCCAGCCGUUAAC 3’
3. What is the tRNA sequence?
ACAGGUCGGCAAUUG
4. What is the amino acid sequence?
Cys-Pro-Ala-Val-Asn
5. A mutation of the DNA in question 1 occurred (in bold and underlined):
3’ ACAGGTAGGCAATTG 5’
5’ TGTCCAGCCGTTAAC 3’
What is the amino acid sequence for the mutant?
Cys-Pro-Ser-Val-Asn
6. What type of mutation is it in question 5?
a. Point mutation
b. Base substitution
c. Missense mutation
d. Silent mutation
e. a and b
f. a, b, and c
g. a, b, and d
7. A different mutation of the DNA in question 1 occurred (in bold and underlined):
3’ AGCAGGTCGGCAATTG 5’
5’ TCGTCCAGCCGTTAAC 3’
What is the amino acid sequence?
Ser-Ser-Ser-Arg-Stop
8. What type of mutation is it in question 7?
a. Point mutation
b.
c.
d.
e.
Frameshift mutation
Silent mutation
a and b
b and c
9. You decide to expose the DNA in question 1 to UV light. Circle the areas on each strand
(below) that will be affected by the UV light exposure.
3’ ACAGGTCGGCAATTG 5’
5’ TGTCCAGCCGTTAAC 3’
10. Name one way the mutation caused by UV light exposure can be repaired. What is the result
of this repair?
Photoreactivation: Original DNA molecule restored
Excision Repair: Mutation eliminated
SOS Repair: Cell survives but still have a lot of mutations
BONUS! (5 points)
In a bacterium, Gene X has a mutation rate of 10-6. Gene D has a mutation rate of 1 in 100,000.
What is the probability that both Gene X and Gene D will be mutated spontaneously in the same
bacterium?
(10-6)x(10-5)=(10-11)
BONUS! (10 points)
In the lab, you made a double mutant bacterium that is lacking
the genes necessary for SOS and excision repair. You expose
the mutant bacteria to UV light first and then to the base analog
5-bromouracil second (see diagram). Except for the UV light
exposure, the bacteria have been kept in the dark. At what step
did the bacteria die (after 1 or after 1 and 2)? Explain how you
arrived at your answer to get FULL credit!
Mutant bacteria are dead after UV Light exposure (step 1).
This is because to correct UV light exposure you need either
photoreactivation, excision repair, or SOS repair. Your mutant
does not have SOS and excision repair. Photoreactivation requires visible light and you kept it in
the dark. So, without a way to repair damaged DNA the bacteria die after step 1 and the exposure
to the 5-Bromouracil was useless because the bacteria were dead.