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Zoo/Bot 3333
Genetics
4/22/05
Quiz 4
For answers to the quiz, click here:
1. The restriction enzyme, AvaI has the six base recognition sequence CPyCGPuG, where Py stands for a
pyrimidine, and Pu stands for a purine). On average, this enzyme might be expected to cut a random DNA
sample every ____________bp.
a) 64; b) 256; c) 1024; d) 1296; e) 4096.
2. The recognition sites for the restriction enzymes BamHI, XbaI and BglII are
5’-GGATCC-3’, 5’-TCTAGA-3’ and 5’-AGATCT-3’, respectively, where the arrows represent the
cut locations for each strand of the palindromic site. Which enzymes leave compatible ends that will
facilitate ligation?
a) All of these enzymes leave ends that are compatible with ends generated by the others; b) None of the
enzymes produce compatible ends; c) Only BamHI and BglII fragments are compatible; d) Only BamHI
and XbaI fragments are compatible; e) only BglII and XbaI fragments are compatible.
3. True or false. One useful property of plasmid vectors used in molecular cloning is their ability to
integrate into the E. coli chromosome.
Questions 4-5 pertain to the following. DNA was prepared from white blood cells isolated from a large
human population. These DNAs were individually digested with EcoRI, subjected to electrophoresis and
Southern blotting, and the blot was probed with a radioactively labeled cloned DNA sequence. Ten
* samples. The figure below indicates the different
different restriction patterns were observed among these
patterns observed in human populations.
4. In the following diagrams, the vertical lines represent EcoRI restriction sites. An asterisk over the site
represents a polymorphism (presence or absence of the site in individuals) in the population. The double
arrow represents the boundaries of the cloned DNA used in the Southern blot analysis. Which of the
following is consistent with the arrangement of EcoRI restriction sites in human genomic DNA?
*
a)
1.0
*
2.1
1.0
1.9
d)
c)
1.0
4.0
1.0
1.9
1.9
2.1
*
*
1.0
*
e)
*
*
b)
2.1
1.9
2.1
5. Suppose individuals 1 and 4 married. Assuming no recombination occurs within the region in question,
how many potentially different patterns would be observed among their progeny on Southern blot analysis?
a) only 1; b) 2; c) 3; d) 4 e) 6.
Question 6 pertains to the following. This region of the genome is known to contain a particular gene,
which encodes a very large protein of 1600 amino acids. A cDNA library primed with oligo dT was made
and a clone derived from that library hybridized to the 5 kb and 3.1 kb restriction fragments only. When
sequenced, this clone was 720 nucleotides in length. A synthetic oligonucleotide that corresponded to
amino acids 3 through 11 of this protein was produced and labeled; it hybridized to the 5 kb, 4 kb and 1.9
kb fragments.
6. True or false. The 3’ end of the mRNA made from this region would be located in the 1 kb restriction
fragment.
7. True or false. It would be impossible to produce a cDNA library of genes expressed in human red blood
cells, since red blood cells do not contain a nucleus.
Questions 8-9 pertain to the following diagram, which represents a region of a DNA sequencing gel
produced using the Sanger chain termination method. The individual lanes represent the reaction products
from the four separate labeling reactions (A,G,C,T) which were loaded at the top of the gel.
8. As deduced from this experiment, the sequence
A
G
C
T
of the strand being copied (template) in this reaction is:
a) 5’-AGACTATCTCTA-3’
b) 5’-ATCTCTATCAGA-3
c) 5 -TAGAGATAGTCT-3’
d) 5- TCTGATAGAGAT-3’
e) 5- GAGTCGCTCTCG-3’
9. Which of the following was NOT present in the test tube
during the ‘A’ DNA synthesis reaction?
a) dATP; b) dGTP; c) ddATP; d) dUTP; e) all of the above
were present in the reaction.
Question 10 pertains to the following. Six independently derived mutants are recovered in Neurospora which
are all unable to grow unless supplemented with compound Z. The mutants are then grown on minimal media
supplemented with one of 6 chemicals all believed to be precursors to compound Z. A summary of the ability
of the mutants to grow on media containing these chemicals is indicated below, where a “+” sign indicates
growth and a “-” sign indicates no growth.
mutant number
precursors added to minimal medium
A
B
C
D
E
F
Z
1
+
+
+
-
-
-
+
2
+
+
+
+
-
-
+
3
+
+
+
+
+
-
+
4
-
-
+
-
-
-
+
5
-
-
-
-
-
-
+
6
-
+
+
-
-
-
+
10. From the above chart, the enzyme that catalyzes the production of compound D appears to be mutant in
strain:
a) 1; b) 2; c) 3; d) 4; e) none of the above.