BIOL/PBIO 3333
Genetics
Quiz 4
April 17, 2015
For answers to the quiz, click here :
Questions 1-4 pertain to the following experiment.
Four pairs of PCR primers were used to amplify
DNA isolated from one man's somatic cells, and
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from 20 single sperm that he donated for this study.
Each primer pair amplifies a different region of the human genome, referred to as genes Q, R, S and T. Each of these amplified regions was then divided into 8 aliquots (i.e. 8 identical subsamples) and these 8 DNA samples were denatured and spotted onto membrane strips for nucleic acid hybridization analysis, as shown in the figure at the right.
The membranes were hybridized to 8 different oligonucleotide probes, which are designed to distinguish single-nucleotide base differences in the DNA. The paired oligonucleotides Q1/Q2, R1/R2, S1/S2 and T1/T2 are therefore regarded as allele-specific oligonucleotide probes
(ASOs). A black circle on the diagram indicates that the amplified DNA hybridized to the indicated ASO probe (e.g. binding of the radiolabeled oligonucleotide to the amplified
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DNA, as detected by autoradiography).
1. Based on the results shown, which gene(s) could be X-linked? a) Q; b) R; c) S; d) T; e) more than one of the above.
2. Based on the results shown, which gene(s) could be on the Y chromosome? a) Q; b) R; c) S; d) T; e) more than one of the above.
3. Which gene(s) must be autosomal and homozygous for a particular ASO? a) Q; b) R; c) S; d) T; e) more than one of the above.
4. On the basis of the above data, what is the map distance between the two genes that are linked to one another? a) 5 map units; b) 10 map units; c) 15 map units; d) 20 map units; e) 25 map units.
5. True or false. Of the four DNA polymerase reactions used for Sanger DNA sequencing, only one contains deoxyadenosine triphosphate.
6. Consider the gel at the right, derived from a sequencing reaction based on the Sanger chain termination method.
The sequence of the TEMPLATE STRAND would be: a) 5'-ACGTGCACGTGC-3'; b) 5'-GCACGTGCACGT-3'; c) 5'-TGCACGTGCACG-3'; d) 5'-GCTAGCGCTAGC-3'; e) 5'-CGTGCACGTGCA-3'.
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Question 7-8 pertains to the flowgram data on the left, obtained from a DNA sequencing run using the massively parallel pyrosequencing technology.
7. True or false. Using the pyrosequencing technology, a base read occurs when a fluorescent molecule is incorporated into the DNA strand, giving off light of a specific wavelength when illuminated by a laser.
8. The first 10 bases of the DNA molecule being synthesized in this flowgram are: a) 5’-TACGTACGTA-3’; b) 5’-TGGAATGCGA-3’; c) 5’-TCAGCGTAAG-3’; d) 5’-CTTACGCTGA-3’; e) none of the above.
Questions 9 and 10 pertain to the following. Six independently derived mutants are recovered in
Neurospora that are all able to grow on compound
Z. The mutants are then grown on minimal media supplemented with one of 6 chemicals all known to be precursors to compound Z. A summary of the ability of the mutants to grow on media containing these chemicals is indicated to the right, where a “+” sign indicates growth and a “-” sign indicates no growth.
Chemical Compounds
Mutant number A B C D E F Z
1 + +

+

+ +
2
3

+

+

+ +
+ + + +

+ +
4
5
6
     
+
  
+
 
+
  
+

+ +
9. The immediate precursor to compound Z (i.e. next to last compound in pathway) is: a) E; b) C; c) F; d) A; e) none of the above.
10. A mutation in gene 2 could lead to an accumulation in which metabolite in the pathway? a) E; b) Z; c) B; d) A; e) none of the above.