BIO130H1 Study Guide - Midterm Guide: Rna Polymerase Ii, Cleavage And Polyadenylation Specificity Factor, Viral Vector

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16 Oct 2018
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1. The following statements describe different aspects of mRNA processing and maturation in
the nucleus of eukaryotic cells. Which of these statements is FALSE?
a. The first step in capping the 5’ end of mRNAs is to remove a terminal 5’ phosphate group.
b. The unusual linkage between guanine and the 5’ end of a mature mRNA is called a 3’ to 5’
triphosphate bridge.
c. In 3’ end processing, the RNA sequence AAUAAA is recognized and bound by the
cleavage and poly-A specificity factor (CPSF).
d. During splicing, snRNPs increase the speed and fidelity of the pre-mRNA splicing.
e. The C-terminal domain of RNA Polymerase II is important for co-transcriptional RNA
processing.
2. As part of a science competition, a student is asked to identify a model of an unknown
molecule as either DNA or RNA. Which of the following characteristics would be the
strongest evidence that the unknown molecule is DNA?
a. The presence of phosphate and sugar.
b. The absence of a hydroxyl group on carbon 2 of the sugar molecule.
c. The absence of thymine.
d. The presence of a ribose sugar.
e. The presence of adenine, guanine, or cytosine.
3. Which of the following CORRECTLY completes the statement?
In an experiment designed to identify sequences capable of initiating DNA replication in
yeast,......
a. the capacity for inhibition of His gene yeast mutants on plates containing histidine was
used to identify ARS sequences.
b. genomic fragments from yeast were cloned into a viral vector.
c. the ability of the His gene mutants to now make histidine was used as an indication that an
origin of replication has been identified.
d. growth of transformants obtained from non-ARS containing plasmids occurs very
frequently and involves integration of the plasmid into the yeast genome.
e. ARS DNA fragments bind to histidine and allow the mutant yeast cells to grow.
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4. Which of the following CORRECTLY completes the statement?
The semi-conservative model of DNA replication ....
a. predicts that each daughter cell contains one parental and one newly synthesized strand
of DNA.
b. is a model of replication not used by prokaryotes with circular chromosomes.
c. is an important strategy for error correction during DNA replication.
d. Answers a) and b) are correct.
e. Answers a) and c) are correct.
5. Which of the following statements concerning proteins is CORRECT?
a. The peptide bond is formed through a hydrolysis reaction.
b. Amphipathic alpha helices have both polar and hydrophobic amino acids.
c. Disulfide bonds are the result of ionic interactions between adjacent cysteine residues.
d. Beta sheets are always anti-parallel, NOT parallel.
e. Proteins are the only molecules that can catalyze reactions in the cell.
6. The two proteins primarily responsible for opening the DNA double helix in advance of the
replication fork and stabilizing the single stranded DNA template are:
a. the sliding clamp and clamp loader.
b. the primase and helicase.
c. the helicase and SSB proteins.
d. DNA ligase and primase.
e. DNA polymerase and DNA helicase.
7. In addition to hydrogen bonds between nitrogenous bases, other important forces that
stabilize the double helix configuration of DNA include:
a. H bonds between deoxyribose and phosphate molecules.
b. van der Waal’s attractions.
c. hydrophobic interactions between the DNA sugar phosphate backbone and the aqueous
environment.
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d. phosphodiester linkages between complementary base pairs.
e. all of the above.
8. Which statement(s) is/are CORRECT?
a. DNA polymerase catalyzes the 5’ to 3’ addition of nucleotides to an existing chain of
nucleotides.
b. At the 3’ end of the DNA strand being synthesized, the OH group located on the
deoxyribose sugar interacts with one of the phosphates of an incoming deoxynucleoside
triphosphate to form a phosphodiester bond and a molecule of pyrophosphate.
c. The primosome is composed of a helicase and a primase.
d. The synthesis of DNA using the lagging strand template requires a series of Okazaki
fragments to be made.
e. All of the statements are correct.
9. A specific line of cultured mouse spleen cells appears to divide only for a limited period of
time, gradually begins to acquire a number of mutations, and eventually the cell culture stops
replicating and dies. A plausible explanation for the behaviour of these cells in culture could
be:
a. The cell line contains a defective DNA polymerase that is unable to replicate genomic
DNA.
b. The cell line is unable to synthesize ATP required for important metabolic reactions.
c. Newly synthesized mRNAs are unable to leave the nucleus and enter the cytoplasm to be
translated.
d. A mutation in the DNA encoding the RNA template used by telomerase eliminates its
capacity for telomere synthesis.
e. The cell line is unable to replicate its mitochondrial genome.
10. Which of the following CORRECTLY completes the statement?
Proof-reading during DNA replication.....
a. requires a conformational shift of the newly synthesized strand from the polymerization
active site to the editing active site of the DNA polymerase.
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