Biology 2581B Study Guide - Midterm Guide: Curt Stern, Branch Migration, Nucleosome

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25 Nov 2012
Department
SURNAME / INITIALS ____________________ (Please Print)
Biology 2581b
FIRST MIDTERM TEST
Feb 5, 2011 - 9am -12 noon
Version 222
25% of Final Mark 3 hours
INSTRUCTIONS
This test paper is composed of 40 equally weighted questions covering 17 sides (excl. cover).
The last page contains a table of critical chi-square values. Please ensure that the exam is
complete.
Although there are no deliberate “tricks” on this paper there is ample opportunity to make
careless oversights; READ THE QUESTIONS CAREFULLY.
Answers will be subject to computerized matching analysis to detect cheating.
Since it is impossible to provide equal access to instructors during the Test, proctors will
NOT answer questions of interpretation.
All answers must be recorded on the Scantron sheets within the 3 hour time limit.
1. Fill in your NAME at the top of the scantron sheet and the exam paper
2. STUDENT NUMBER - Print the digits of your student number in the squares provided.
Mark the corresponding bubble in the column below each printed digit.
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3. SECTION AND ANSWER SHEET - Leave these areas blank.
4. In the EXAM CODE section enter 222
5. Mark one choice from the alternatives provided for each question.
6. Submit your test paper and the Scantron sheet SEPARATELY.
1. Consider a long, linear molecule of dsDNA, one end of which is rotated six times with
respect to the other end introducing negative (-) writhe. The two ends are then joined together
to create a covalently closed circle. Which of the following statements concerning this molecule
are true?
i) The molecule is underwound.
ii) The molecule is storing positive superhelical energy
iii) The molecule would form positive supercoils.
iv) The molecule is in an unfavourable state to promote transcription.
A. Only i) is true.
B. Only ii) is true.
C. Only i), ii), and iv) are true.
D. All are true.
E. None are true.
2. Which of the following is not true of histones?
A. They are rich in positively charged amino acids
B. They are associated with the nucleosome.
C. H2A, H2B, H3 and H4 form the nucleosome core.
D. They are found in the nucleus.
E. A complex of H1 and H2A help keep DNA properly wound around the nucleosome core.
3. Suppose that pigmentation in rabbits is controlled by two genes (E and H). Each gene
exhibits complete dominance, and the relationship between genotypes and phenotypes are listed
below:
Genotype Phenotype
E-H- albino
eeH- brown
E-hh albino
eehh albino
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What phenotype ratio would be expected among the progeny of a cross between dihybrid
rabbits?
A. 9 albino : 7 brown
B. 9 brown : 7 albino
C. 3 brown : 1 albino
D. 13 brown : 3 albino
E. 13 albino : 3 brown
4. In a linear eukaryotic chromatin sample, which of the following is formed into radial loops
that are attached to the central scaffold?
A. DNA without any attached histones.
B. DNA in a complex with H1 only.
C. The 10 nm fiber.
D. The 30 nm fiber.
E. None of the above.
5. Which of the following statements regarding the double strand break repair model of
recombination are true?
i) recombination is initiated by a double stranded break in one chromatid
ii) recombination events can occur anywhere along the DNA molecule
iii) resolution of Holliday junctions in the same plane results in an aborted crossover
iv) branch migration can result in the creation of heteroduplex regions ranging from tens
to thousands of base pairs.
A. Only i) is true.
B. Only i) and ii) are true.
C. Only i), ii) and iii) are true.
D. All are true.
E. None are true.
6. The sequence of a mature mRNA is 5’-AUCAAAUGGACUUUG-3’. What is the
corresponding sequence of the template strand of the gene encoding this message?
A. 5’-ATCAAATGGACTTTG-3’
B. 3’-ATCAAATGGACTTTG-5’
C. 5’-TAGTTTACCTGAAAC-3’
D. 3’-TAGTTTACCTGAAAC-5’
E. 3’-AUCAAAUGGACUUUG-5’
7. Which of the following statements regarding double stranded DNA is true?
i) The angle between the glycosidic bonds of the minor groove is 240 degrees.
ii) G = C in each individual strand of DNA within the double helix
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