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Biology 200, Autumn 2014
Quiz 3 KEY
NOTE: This key is for version A – look carefully if you have version B!
1. (4 pts) For each of the following molecules or structures, write the letter for the category of
biological macromolecule it is or is made of. IF IT CONSISTS OF TWO TYPES, write both
letters. Categories may be used once, more than once or not at all.
(0.5 pts each)
a. ___N__ intron
e. ___N___ template for telomerase
Category:
b. ___P___ Lac repressor
f. ____P__ basal transcription factor
C = carbohydrate
c. _N&P_ spliceosome
g.____C__ lactose
L = lipid
d. ___P__ ubiquitin
h. ___N___ cAMP
N = nucleotide or nucleic acid
P = protein or amino acid
origin
2. (8 pts) The diagram below shows a short eukaryotic
chromosome after replication is complete.
The parental DNA strands are black, the new DNA
strands are gray. (Arrows indicate 3' ends)
"Mut 1" and "Mut 2" are for part 'd'.
a. (2 pts) Which enzymes were needed for DNA
replication? (Circle all correct answers)
DNA polymerase I
release factor
primase
a
b
c
mut 1
d
mut 2
spliceosome
b.(2 pts)If telomerase is active, to which end(s) will it add dNTPs? (Circle ALL correct a
b c d
c. (1 pt) Does the DNA molecule on the bottom have an origin? yes
d. (1 pt) Which mutation, 1 or 2, would more likely have an effect on DNA replication? 2
e. (2 pts) In which of the following cell types could you find replicated DNA? (Circle ALL correct
answers)
cancer cells
neurons in G0
embryonic cells about to divide
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Biology 200, Autumn 2014
Quiz 3 KEY
3. (5 pts) a. (2 pts) Imagine you have a wild-type (normal) E. coli cell. It is being grown in
glycerol, with neither glucose nor lactose present. Circle all proteins that will be bound to the
DNA of the Lac Operon or its regulatory regions.
CAP protein (with cAMP)
sigma/RNA polymerase
lac repressor
b. Now you have an E. coli mutant in which the Lac Operon's promoter sequence has changed –
it is now a very good binding site for sigma. Consider this mutant in each condition below and
then write either "+" for high transcription rate or "-" for low or no transcription of the operon.
(1 point each)
lactose alone: _____+_____
glucose alone: ____-______
glucose and lactose: ____+______
4. (8 pts) The diagram to the
right represents a portion of
a eukaryotic chromosome.
"P" stands for promoter,
"E" stands for enhancer and
"T" stands for terminator.
a. (1 pt) Which molecule binds to "E"? (Circle the ONE best answer)
- RNA polymerase
- a regulatory transcription factor
- a basal transcription factor
b. (2 pts) Which of the diagrams below could represent possible spliced mRNAs from this gene?
(Circle ALL correct answers)
c. (1 pt) Name one modification added to the spliced mRNA before it exits the nucleus: 5' Cap or
poly-A tail
d. This gene codes for a histone deacetylase (HDAC). This HDAC protein acts on histones of a
tumor suppressor gene elsewhere in the DNA. Imagine a mutant that had an insertion of one
base pair four nucleotides after the start codon.
(1 point each)
i. What type of mutation is this? (Circle ONE) silent
frameshift
missense
For questions ii-iv, answer "increase", "decrease" or "stay the same".
ii. How will the amount of HDAC mRNA change? stay the same
iii. How will the amount of tumor suppressor mRNA change? increase
iv. How will the likelihood of cancer change? decrease
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