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Nucleosomes that are positioned like beads on a string over a region of DNA can
interact to form higher orders of chromatin structure. Which of the following factors
can contribute to the formation of the 30-nm chromatin fiber from these nucleosomes?
A.Interactions that involve the histone tails of neighboring nucleosomes
B.Interaction of the linker histone H1 with each nucleosome
C.Binding of proteins to DNA or the histones
D.ATP-dependent function of chromatin remodeling complexes
E.All of the above
What are the consequences for the cell of the "fractal globule" arrangement of
chromosome segments?
A.The chromosomes cannot be condensed maximally this way.
B.The neighboring regions of DNA are furthest from each other in the
three-dimensional space.
C.The ability of the chromatin fiber to fold and unfold efficiently is maintained.
D.Dense packing is permitted, but the ability to easily fold and unfold the chromatin is
prohibited.
E.None of the above.
The formation of a stable ternary complex involving Ran GTPase, a nuclear transport
receptor, and a cargo protein occurs in ___
A.both nuclear import and export.
B.nuclear import , but not export.
C.nuclear export, but not import.
D.neither nuclear import nor export.
Compared to the human genome, the genome of yeast typically has ___
A.more repetitive DNA.
B.longer genes.
C.more introns.
D.longer chromosomes.
E.a higher fraction of coding DNA.
The two monolayers of the plasma membrane in a human red blood cell ___
A.have different overall electrical charges, with negatively charged phospholipids (e.g.
phosphatidylserine) normally enriched in the inner monolayer.
B.have the same abundance of phosphatidylinositol.
C.exchange phospholipids only through spontaneous flip-flops.
D.both contain glycolipids.
E.both contain gangliosides.
Cells expressing either N-cadherin (A), high levels of E-cadherin (B), or low levels of
E-cadherin (C) have sorted themselves out on a substratum in a cadherin-dependent
manner as shown in the schematic drawing below. Which cells (A to C) would you
expect to correspond to white, gray, and black in the drawing, respectively? Your
answer would be a three-letter string composed of letters A to C only, e.g. CAB.
The ³-tubulin ring complex is to microtubules what ... is to actin filaments.
A.the Arp 2/3 complex
B.the dynactin complex
C.the troponin complex
D.formin
E.contractile ring
The gene encoding Hes7 in mouse contains three introns. Any or all of these introns can
be deleted to alter the delay associated with transcription and splicing of Hes7 mRNA.
As a result of such deletions, either the oscillation frequency of this gene's expression
can change (result 1) or the oscillatory behavior can disappear altogether (result 2). One
of these two results is obtained when only one intron is deleted from the gene, while the
other result is obtained when all three introns are removed. Would you expect the
oscillation frequency to increase or decrease if result 1 is obtained? Which result (1 or
2) would you expect to observe when all three introns are deleted?
A.Increase; result 1
B.Increase; result 2
C.Decrease; result 1
D.Decrease; result 2
In lamellipodia, actin polymerization is nucleated by ...(1), while depolymerization is
catalyzed by ...(2).
A.(1) formin; (2) gelsolin
B.(1) Arp 2/3 complex; (2) gelsolin
C.(1) formin; (2) cofilin
D.(1) Arp 2/3 complex; (2) cofilin
E.(1) formin; (2) capping protein
Apoptotic cells are efficiently phagocytosed by neighboring cells or macrophages.
Which of the following DOES NOT normally happen in this process?
A.The apoptotic cell releases some of its cytoplasmic content to induce a local
inflammatory response.
B.The apoptotic cell exposes phosphatidylserine at its surface, which interacts with
receptor proteins on the surface of phagocytes via "bridging" proteins.
C.The apoptotic cell loses or inactivates "don€t eat me" signals.
D.The apoptotic cell rounds up and detaches from its neighbors, which facilitates
phagocytosis.
The Rb gene in retinoblastomas is similar to the Apc gene in polyposis colon
carcinomas in that both genes ...
A.are tumor suppressors.
B.are mutated in one copy in all cells of patients with a hereditary form of the cancer.
C.are in a locus that shows loss of heterozygosity in the hereditary form of the cancer.
D.should be inactivated in both copies to cause the nonhereditary form of the cancer.
E.All of the above.
Indicate which one of the indicated types of coat proteins (A, B, and C) in the
schematic diagram below corresponds to COPI, COPII, and clathrin, respectively. Your
answer would be a three-letter string composed of letters A to C only, e.g. CBA.
Indicate whether each of the following DNA lesions is typically repaired via the base
excision (B) or nucleotide excision (N) repair pathway? Your answer would be a
four-letter string composed of letters B and N only, e.g. BBBB.
1>Deaminated cytosines
2>Depurinated residues
3>Thymine dimers
4>Bulky guanine adducts
Fill in the gap in the following paragraph using what you know about the activities of
the proteins involved in DNA replication.
"Mitochondrial DNA replication requires a set of proteins similar to those used for the
replication of the nuclear genome. However, mitochondria lack a dedicated DNA ... and
use the mitochondrial RNA polymerase instead."
A DNA nucleotide pair has an average mass of approximately 660 daltons. Knowing
the number of nucleotides in the human genome, how many picograms of DNA are
there in a diploid human nucleus? Avogadro's number is 6 x 1023. Write down the
picogram amount without decimals (round the number to the closest integer), e.g. 23
pg.
Indicate whether each of the following descriptions better applies to class switching
(C), somatic hypermutation (S), or both (B). Your answer would be a four-letter string
composed of letters B, C, and S only, e.g. SSSB.
( )It is dependent on activation-induced cytidine deaminase.
( )It involves sequence changes in the CH domains only.
( )It increases the affinity of antibody-antigen binding.
( )It takes place in germinal centers after antigen stimulation.
Sort the following molecules (A to E) based on the oxidation of the carbon atom, from
higher to lower oxidation states. Your answer would be a five-letter string composed of
letters A to E only, e.g. ADCBE. Put the letter corresponding to the highest oxidation
level on the left.
