In assembling a nucleosome, normally the ___(1) histone dimers first combine to form
a tetramer, which then further combines with two ___ (2) histone dimers to form the
octamer.
A.1: H1-H3; 2: H2A-H2B
B.1: H3-H4; 2: H2A-H2B
C.1: H2A-H2B; 2: H1-H3
D.1: H2A-H2B; 2: H3-H4
E.1: H1-H2; 2: H3-H4
Sort the following events to reflect the order in which they typically take place during
the reprogramming of fibroblasts to induced pluripotent stem cells. Your answer would
be a four-letter string composed of letters A to D only, e.g. ADBC.
(A)Sustained endogenous expression of Oct4
(B)Gain of embryonic marker protein
(C)Loss of fibroblast-specific marker protein
(D)OSKM overexpression
The following diagram depicts the topology of a multipass transmembrane protein in
the endoplasmic reticulum (ER) membrane. Which set of helices act as stop-transfer
signals in this protein?
A.1, 2, 3
B.4, 5, 6
C.1, 3, 5
D.2, 4, 6
E.1, 6
Imagine a cellular protein composed of 3000 amino acid residues in one continuous
polypeptide chain. This protein is almost certainly €¦___
A.extracellular.
B.globular.
C.multidomain.
D.composed of mostly ±-helical regions.
E.intrinsically disordered.
Certain cysteine-containing proteins of the mitochondrial intermembrane space are
imported from the cytosol with the help of the Mia40 protein via a disulfide relay
system. What drives the unidirectional import of these proteins? Are these proteins
reduced or oxidized at their cysteine residues upon import?
A.ATP hydrolysis; oxidized
B.The electron-transport chain; oxidized
C.ATP hydrolysis; neither oxidized nor reduced
D.ATP hydrolysis; reduced
E.The electron-transport chain; reduced
If explants that can produce axons from either the anterior or posterior retina are placed
on a culture substratum that is coated by either anterior or posterior tectal
membranes, …
A.anterior axons grow only on the anterior tectal membranes, whereas posterior axons
grow only on the posterior tectal membranes.
B.anterior axons grow only on the posterior tectal membranes, whereas posterior axons
grow only on the anterior tectal membranes.
C.anterior axons grow only on the anterior tectal membranes, whereas posterior axons
grow on both anterior and posterior tectal membranes.
D.anterior axons grow only on the posterior tectal membranes, whereas posterior axons
grow on both anterior and posterior tectal membranes.
E.anterior axons grow on both the anterior and posterior tectal membranes, whereas
posterior axons grow only on the anterior tectal membranes.
In Sanger sequencing, does each labeled DNA molecule have a fluorescently labeled
dideoxyribonucleotide at its 5′ end or its 3′ end? Do the labeled nucleotides lack the 2′
or 3′ hydroxyl group?
A.3′ end; 2′ hydroxyl group only
B.3′ end; 3′ hydroxyl group only
C.5′ end; 2′ hydroxyl group only
D.5′ end; 3′ hydroxyl group only
E.3′ end; both hydroxyl groups
Indicate whether each of the following descriptions better applies to cellulose
microfibrils (C) or pectins (P) in plant cell walls. Your answer would be a five-letter
string composed of letters C and P only, e.g. CPPPP.
( )It is made into a network by cross-linking glycans.
( )It is particularly abundant in the middle lamella.
( )Divalent ions such as calcium can cross-link it to form gels.
( )It forms more homogeneous polymers.
( )It contains many negatively charged galacturonic acid units.
The structural formulas for a few antibiotics that target the ribosome are shown below.
Which one do you think is that of puromycin? Hint: puromycin mimics the structure of
an amino acid linked to a tRNA molecule.
Source: Wikipedia.com License: Public domain.
Sort the following events in the order that they occur during transcription initiation in
Escherichia coli. Your answer would be a four-letter string composed of letters A to D
only; e.g. DCAB.
(A)Abortive initiation trials
(B) Factor release from the RNA polymerase holoenzyme
(C)Binding of the holoenzyme to the promoter in the “closed” complex
(D)Formation of the transcription bubble
Which of the following is normally NOT found in a eukaryotic membrane?
A.Cholesterol
B.Phosphatidylinositol
C.Sphingomyelin
D.Ganglioside GM1
E.Octylglucoside
In the first reaction of the glycolytic pathway, the enzyme hexokinase uses ATP to
catalyze the phosphorylation of glucose, yielding glucose 6-phosphate and ADP. The
G° value for this reaction is -17 kJ/mole. The enzyme glucose 6-phosphatase catalyzes
a “reverse” reaction, in which glucose 6-phosphate is converted back to glucose, and a
phosphate is released. The G° value for this reaction is -14 kJ/mole. What is the G°
value for the following reaction?
ATP + H2O –> ADP + Pi
A.-3 kJ/mole
B.+3 kJ/mole
C.-31 kJ/mole
D.+31 kJ/mole
E.-15.5 kJ/mole
Which mass spectrometry instrument is most suitable for determining all the proteins
present in an organelle?
A.MALDI-TOF
B.MS/MS
C.LC-MS/MS
D.GC-MS
In a bacterium that is normally cylindrical in shape, loss of either of two genes A and B
results in round cells. Additionally, gain-of-function mutations in gene A can rescue the
phenotype of gene B loss-of-function mutants. What phenomenon best describes this
observation? The product of which gene is more likely to function upstream of the other
one in determining cell shape in this bacterium?
A.Suppression; gene A
B.Suppression; gene B
C.Complementation; gene A
D.Complementation; gene B
Indicate true (T) and false (F) statements below regarding the mTOR complexes. Your
answer would be a four-letter string composed of letters T and F only, e.g. TTTF.
( )mTOR in complex 1 contains the protein raptor, is sensitive to rapamycin, and
stimulates cell growth.
( )Akt activation is stimulated by mTOR in complex 2, which contains the protein
rictor.
( )Akt activates mTOR in complex 2 by activating a Rheb-GAP called Tsc2.
( )mTOR in complex 1 is activated in the presence of growth factors.
When the gene encoding a certain cytoskeleton protein is deleted, the resulting mutant
cells round up and do not form their normal appendages. These mutants can be rescued
when a gene encoding an N-terminal green fluorescent protein (GFP) fusion of the
protein is expressed, but not when a gene encoding a C-terminal GFP fusion is
expressed. Which fusion protein (N or C) is appropriate to use in studying cellular
localization and activity? Write down N or C as your answer.
You grow a tumor-derived cell line in a suspension culture, in which the cells are seen
either as single cells or in cell clusters. The cells have been engineered to express green
fluorescent protein (GFP) under the control of the mitogen-activated protein kinase
(MAP kinase) pathway. To your culture media, you add different concentrations of
fibroblast growth factor (FGF)-which is known to activate the MAP kinase pathway in
these cells-and briefly incubate the cells before harvesting them. You also collect, under
a microscope, hundreds of individual cell clusters from each suspension. You then
disaggregate the cells in all of your samples and use a FACS (fluorescence-activated
cell sorting) machine to measure the GFP signal intensity in individual cells. Finally,
you plot the results as histograms, as shown below.
According to these results, which of the following schematic drawings better represents
the expression of GFP (a proxy for MAP kinase activation) in the culture after
intermediate FGF stimulation? In these drawings, higher GFP expression is represented
by a darker shade.
You have performed a chromosome conformation capture (3C) experiment to study
chromatin looping at a mouse gene cluster that contains genes A, B, and C, as well as a
regulatory region R. In this experiment, you performed in situ chemical cross-linking of
chromatin, followed by cleavage of DNA in the nuclear extract with a restriction
enzyme, intramolecular ligation, and cross-link removal. Finally, a polymerase chain
reaction (PCR) was carried out using a forward primer that hybridizes to a region in the
active B gene, and one of several reverse primers, each of which hybridizes to a
different location in the locus. The amounts of the PCR products were quantified and
normalized to represent the relative cross-linking efficiency in each analyzed sample.
You have plotted the results in the graph below. The same experiment has been done on
two tissue samples: fetal liver (represented by red lines) and fetal muscle (blue lines).
Interaction of the A, B, and C genes with the regulatory R region is known to enhance
expression of these genes. Indicate true (T) and false (F) statements below based on the
results. Your answer would be a four-letter string composed of letters T and F only, e.g.
TTTF.
( )The B gene would be predicted to have higher expression in the fetal liver compared
to the fetal muscle tissue.
( )Interaction between the R region and the B gene involves the A gene looping out.
( )Interaction between the R region and the B gene involves the C gene looping out.
( )In fetal muscle, the B gene definitely does not engage in looping interactions with
any other elements in the cluster.
Indicate whether each of the following descriptions better applies to the intracellular (I)
or extracellular (E) domain of integrins. Your answer would be a four-letter string
composed of letters I and E only, e.g. EEEE.
( )It binds to talin.
( )It binds to the RGD tripeptide motif.
( )It is bulkier.
( )It contains divalent cation-binding domains.
Indicate true (T) and false (F) statements below regarding receptor-mediated
endocytosis of LDL particles. Your answer would be a four-letter string composed of
letters T and F only, e.g. TTTF.
( )LDL receptors are normally degraded in the lysosome along with their LDL ligands.
( )LDL receptors that do not bind to extracellular LDL cannot be internalized in
clathrin-coated vesicles.
( )A mutation that impairs the attachment of an LDL receptor to a clathrin-coated pit
would cause depletion of blood LDL levels.
( )LDL receptors at the plasma membrane are usually concentrated in clathrin-coated
pits.