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These proteins are found in the budding yeast Saccharomyces cerevisiae; they form
"neck filaments" between a mother cell and its growing bud, and help polarize protein
distribution between the two. These proteins ...
A.can polymerize to form filaments and sheets.
B.bind GTP.
C.are also involved in contractile ring formation during cytokinesis in animal cells.
D.form filaments that are thought to be nonpolar.
E.All of the above.
Which of the following processes that happens inside a cell DOES NOT normally
require consumption of free energy by the cell?
A.Replication of the genetic material
B.Import of nutrients from the environment
C.Diffusion of small molecules within the cell
D.Regulation of gene expression
E.Synthesis of enzymes that catalyze cellular reactions
The telomerase enzyme in human cells ___
A.has an RNA component.
B.extends the telomeres by its RNA polymerase activity.
C.polymerizes the telomeric DNA sequences without using any template.
D.removes telomeric DNA from the ends of the chromosomes.
E.creates the "end-replication" problem.
The Trp operon in Escherichia coli encodes the components necessary for tryptophan
biosynthesis. In the presence of the amino acid in a bacterium, ___
A.the tryptophan operator is bound to the tryptophan repressor.
B.the tryptophan repressor is bound to bacterial RNA polymerase.
C.the expression of the tryptophan repressor is shut off.
D.the operon genes are expressed.
E.All of the above.
Most fish genomes are at least 1 billion nucleotide pairs long. However, the genome of
the puffer fish Fugu rubripes is quite small at only about 0.4 billion nucleotide pairs,
even though the number of Fugu genes is estimated to be comparable to that of its
relatives which have larger genomes. What do you think mainly accounts for the Fugu
genome being this small?
A.Evolutionary advantage of extremely small exon sizes in the Fugu lineage
B.Unusual disappearance of all intronic sequences from the Fugu genome
C.Increased abundance of transposable elements in the Fugu genome
D.Increased occurrence of mitotic whole-chromosome loss in the Fugu lineage
E.Low relative rate of DNA addition compared to DNA loss in the Fugu lineage
In insects such as Drosophila melanogaster, electrical synapses are abundant in the
ventral nerve cord. Unlike a chemical synapse, the cytosols of pre- and postsynaptic
cells in an electrical synapse are connected, allowing action potentials to spread rapidly
and without delay. What junctional proteins in the flies are chiefly responsible for this
unique feature of the electrical synapses?
A.Cadherins
B.Claudins
C.Connexins
D.Innexins
E.Integrins
Which of the following cells in a healthy adult human show the highest turnover?
A.Neurons of the hippocampus
B.Epithelial cells of the urinary tract
C.Hepatocytes of the liver
D.Epithelial cells of the small intestine
E.Neutrophils of the blood
Sort the following steps in the common procedure to create transgenic plants. Your
answer would be a four-letter string composed of letters A to D, e.g. DABC.
(A)Callus growth
(B)Agrobacterium infection
(C)Shoot/root induction
(D)Removal of leaf tissue from a plant
Of the following proteins or protein complexes, which one does NOT typically interact
with an elongating RNA polymerase II?
A.Histone-modifying enzymes
B.Capping enzymes
C.Chromatin remodeling complexes
D.Mediator complex
E.Histone chaperones
Two loci on a human chromosome are about 1,500,000 nucleotide pairs apart and are
found to recombine in about 2% of gametes during gametogenesis. Consistently, each
genetic map unit (which corresponds to 1% recombination) in humans is equivalent to a
physical distance of about ___ nucleotide pairs.
A.30 million
B.7.5 million
C.3 million
D.0.75 million
E.0.3
To ensure the fidelity of splicing, the spliceosome___
A.hydrolyzes ATP to undergo complex rearrangements.
B.examines the splicing signals on the pre-mRNA several times.
C.assembles on the pre-mRNA co-transcriptionally.
D.takes advantage of "exon definition."
E.All of the above.
You have engineered a fusion protein composed of a cis Golgi resident protein and the
green fluorescent protein. Similarly, you have made a fusion protein composed of a
trans Golgi protein and the red fluorescent protein. You express these proteins in cells
and follow individual Golgi cisternae using fluorescence microscopy. You observe that
each individual cisterna emits a green, faint yellow, or red fluorescent signal at different
times: it initially shows green fluorescence, but the green fluorescent signal fades away
with time, and instead red fluorescence appears in the same cisterna. Additionally, you
do not observe any red fluorescent cisterna that becomes green over time. Do these
observations agree better with the cisternal maturation model (C) or the vesicle
transport model (V) for the organization of Golgi stacks? Write down C or V as your
answer.
You have analyzed a large set of human cancer-critical genes for a selected group of
carcinomas, classifying each of the genes based on whether they are known to undergo
somatic or germ-line mutations, as well as based on whether they are dominant or
recessive. You then group them and plot the statistics in the following histograms.
Which group (a or b) do you think represents somatic, as compared to germ-line,
mutations? Which group (1 or 2) do you think represents dominant, as compared to
recessive, mutations? (Note that the sum of percentages of somatic and germ-line
mutations is more than 100%, since some genes are mutated in both somatic and germ
cells).
A.a; 1
B.a; 2
C.b; 1
D.b; 2
Indicate true (T) and false (F) statements below regarding ion channels in cellular
membranes. Your answer would be a four-letter string composed of letters T and F only,
e.g. TTTT.
( )With patch-clamp recordings, it is possible to study ion transport through a single
molecule of a channel protein.
( )Cells that are not electrically excitable often lack gated ion channels in their plasma
membrane.
( )The aggregate current crossing a patch of plasma membrane represents the degree to
which each individual channel is open at that time.
( )Patch-clamp recordings have shown that any voltage-gated ion channel opens as soon
as the membrane potential is altered.
Two approaches have been devised to deal with the problem of blurring in light
microscopy with thicker samples. Indicate whether each of the following descriptions
better applies to confocal design (C) or image deconvolution (D). Your answer would
be a three-letter string composed of letters C and D only, e.g. CCD.
( )It is normally faster.
( )It requires a higher degree of sample illumination.
( )It can be used to obtain images from relatively deeper parts of the specimen.
Indicate whether each of the following descriptions better applies to the scanning (S) or
transmission (T) electron microscopy techniques. Your answer would be a four-letter
string composed of letters S and T only, e.g. TSTS.
( )It generally has a greater depth of field.
( )It is usually smaller, cheaper, and simpler.
( )It detects electrons that are scattered or emitted from the specimen.
( )It is used to create electron-microscope tomograms.
To prevent spurious transcription from a gene, acetylation of histones-which is carried
out by histone acetyl transferases ahead of a moving RNA polymerase II-is quickly
reversed by histone deacetylases and histone methyl transferases in the wake of the
polymerase, leaving a trail of specific methylated histones. Which of the following
curves do you think better represents the distribution of this specific histone
methylation mark with respect to a gene?
Heart conditions known as cardiomyopathies include two main subtypes, namely the
hypertrophic and dilated cardiomyopathies, in which some portions of the cardiac
muscle become stiff or dilated, respectively. Drugs such as the calcium channel blocker
verapamil are used to treat the former, while the Na+-K+ ATPase inhibitor digoxin
(which elevates intracellular calcium concentration in cardiac muscle cells) is
sometimes used for the latter. Mutations in the subunits of the troponin complex are
among the genetic causes of these diseases, and can be grouped into mutations that
result in either decreased (D) or increased (I) calcium-ion sensitivity of actin-myosin
contraction. Which of these mutations would you expect to be associated with
hypertrophic cardiomyopathy? Write down D or I as your answer.
