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questions are from the practice exam, the top questions, and the in-class slideshow.
The Force for axoneme bending is derived from the…
Sliding movement of central pair microtubules
sliding movement of outer doublet microtubules
contraction of central pair microtubules
contraction of outer doublet microtubules
sliding movement of outer doublet microtubules
Cytosolic dynein is linked to vesicles and chromosomes via
a) its head domain.
b) its stalk domain.
c) kinesin I.
d) dynactin.
d) dynactin
Which of the following types of cells would you expect to contain a high density of intermediate filaments in their cytoplasm?
a E coli
b Sperm cell
c Plant cell
d Smooth muscle cell in the digestive tract
d Smooth muscle cell in the digestive tract
The nuclear envelope breaks down at the start of prometaphase because
a sister chromatids separate.
b growing microtubules break the envelope down.
c replicated chromosomes condense.
d nucleoporins and nuclear lamina become phosphorylated.
d nucleoporins and nuclear lamina become phosphorylated.
Chromosome painting involves
a staining chromosomes with Giemsa reagent.
b hybridizing fluorescent probes to chromosomes.
c hybridizing radioactive probes to chromosomes.
d all of the above.
b hybridizing fluorescent probes to chromosomes.
Kinetochores assemble at the
a centrosome.
b origin of replication.
c telomere.
d centromere.
d centromere.
A bi-oriented chromosome is one that is:
a attached at one kinetochore by a microtubule.
b entering prometaphase.
c moving toward the minus end of a microtubule only.
d attached at both kinetochores by microtubules.
d attached at both kinetochores by microtubules.
Capture of microtubule (+) ends by chromosomes occurs during
a metaphase.
b prometaphase
c anaphase
d telophase
b prometaphase
During _______, a nuclear membrane reforms around each daughter nucleus, and the chromosomes decondense.
a prophase
b metaphase
c telophase
d anaphase
c telophase
The loss of its cyclin causes a Cdk to
a become active.
b be degraded by the proteasome.
c become inactive.
d phosphorylate its target substrates.
c become inactive.
Which of the following initiates M phase?
a activation of mitotic CDKs.
b activation of S-phase CDK complexes.
c activation of APCs.
d activation of G1 CDK complexes.
a activation of mitotic CDKs.
During which stage of the cell cycle is the chromosome content of a mammalian liver cell 1n?
a G1
b G0
c S
d M
e None of the above.
e None of the above.
A cell is considered cancerous when it acquires a mutation that makes it unable to regulate its cell cycle and, as a result, divides more often than a normal, healthy cell. Based on the increased energy demands of this condition, what would you expect to be true about glycolysis in cancer cells?
a Glycolysis occurs at a faster rate in cancer cells than in healthy cells.
b Glycolysis occurs at a faster rate in healthy cells than in cancer cells.
c Glycolysis occurs at the same pace in healthy cells and cancer cells.
a Glycolysis occurs at a faster rate in cancer cells than in healthy cells.
Cancer is particularly dangerous and a difficult disease to treat because it can metastasize, or spread, to other parts of the body. Which is an essential process that allows cancer to metastasize?
a generation of a new network of blood vessels through angiogenesis
b programmed cell death through the process of apoptosis
c exposure to toxins, including tobacco and asbestos
d inhibition of cell division as a result of increased cell density in a tissue
a generation of a new network of blood vessels through angiogenesis
Which fact regarding mammalian meiosis is responsible for the increased incidence of Down syndrome in offspring of older women?
a Chromosome 21 is particularly susceptible to nondisjunction.
b Mammalian oocytes are arrested in G2 until ovulation.
c Cohesins become uncleavable after a prolonged G2 period.
d The presence of two X chromosomes increases dosage of a cohesion cleavage factor, promoting nondisjunction in oocytes compared with sperm.
b Mammalian oocytes are arrested in G2 until ovulation.
Which of the following properties are shared by all stem cells?
a Pluripotent.
b Self-renewal.
c Totipotent.
d Unipotent.
b Self-renewal.
6. Centrosome duplication occurs during
a. prophase
b. metaphase
c. anaphase
d. telophase
e. interphase
e. interphase
8. In the mitotic spindle, astral microtubules function to
a. connect the spindle poles.
b. attach chromosomes to the spindle.
c. carry out cytokinesis.
d. allow the spindle to interact with the plasma membrane.
d. allow the spindle to interact with the plasma membrane.
10. Exit from mitosis depends upon the degradation of
a. cohesion.
b. condensin.
c. mitotic cyclin.
d. securin.
e. separase.
C. Mitotic Cyclin
11. Histones are modified by
a. phosphorylation
b. acetylation
c. methylation
d. all of the above.
d. all of the above
13. Separase initiates sister chromatid segregation at anaphase by cleaving
a. APC.
b. Cdc20.
c. cyclin B.
d. cohesin.
e. securin.
d. cohesin.
14. Directional transport through the nuclear core complex depends on
a. Ras
b. Ran
c. trimeric G-protein
d. ATP
b. Ran
15. During meiosis, homologs are paired along their entire length at
a. interphase.
b. leptonene.
c. pachytene.
d. metaphase.
d. metaphase
16. The predominant chromosomal defect in Down syndrome patients is
a. trisomy chromosome 21.
b. trisomy chromosome 22.
c. trisomy chromosome 23.
d. none of the above.
a. trisomy chromosome 21.
17. Separation of spindle poles during spindle formation and anaphase B most likely depends on which of the following?
a. (+) end-directed microtubule motors at the cell cortex
b. (+) end-directed microtubule motors at the kinetochore
c. (−) end-directed microtubule motors in the microtubule overlap zone
d. (+) end-directed microtubule motors in the microtubule overlap zone
d. (+) end-directed microtubule motors in the microtubule overlap zone
18. Which of the following occurs during anaphase A?
a. The spindle elongates.
b. Kinetochores remain attached to shortening kinetochore microtubules.
c. Chromosomes move to the spindle equator.
d. The spindle poles move closer together
b. Kinetochores remain attached to shortening kinetochore microtubules.
19. Which of the following inhibits cyclin A/Cdk2 activity?
a. INK4
b. p21CIP
c. Rb
d. b and c
b. p21CIP
20. Which of the following is equivalent to MPF (the maturation promoting factor)?
a. APC/C.
b. G1 cyclin-Cdk.
c. Mitotic cyclin-Cdk.
d. S-phase cyclin-Cdk.
c. Mitotic cyclin-Cdk.
T F -- Proteins with NLS sequence are transported through the nuclear pore in fully folded conformation.
True
T F -- The nucleolus is a sub-organelle inside the nucleus, and is surrounded by a double-layered membrane.
False (the nucleolus is a sub-organelle inside the nucleus but it is not bound by a membrane)
T F -- Three functional chromosome elements are origin of replication, centromere, and telomere.
True
T F -- The N-terminal of Histone proteins extends from the core particle, forming the Histone “tail”.
True
T F -- The core nucleosome particle is composed of four types of histone proteins: H1, H2A, H2B, and H3.
False, it contains H2A, H2B, H3, and H4.
T F -- Sister chromatids are tethered together by a protein complex called condensin.
True
T F -- The plus (+) end of microtubule project away from the mitotic spindle pole.
True
T F -- The mitotic spindle determines the plane of cell division in animal cells.
True
T F -- Mitotic cyclin is polyubiquitinated by APC.
True
T F -- The cell cycle control system is a protein-kinase based machine.
True
T F -- Four phases of the cell cycle are named sequentially as G0, S, G1, and M phase.
False, they are G1, S, G2, and M phase
T F -- Centrosomes are duplicated in mitosis to organize the microtubule spindles.
True
T F -- The spindle assembly checkpoint monitors microtubule attachment and tension at the kinetochore: unattached kinetochores can generate a “wait” signal to prevent anaphase entry.
True
T F -- iPS cells, induced pluripotent stem cells, are derived from blastocyst inner mass cells.
False. They are derived from somatic cells.
T F -- Poly-ubiquitinated proteins are targeted to the proteasome for degradation.
True
T F -- Somatic cell nuclear transfer (SCNT) induces pluripotent stem cells directly from somatic cells, thus bypassing the need for human “cloning”
True
What are the biochemical activities of Wee1 and Cdc25 proteins? How do these activities regulate mitotic cyclin-Cdk1?
Wee1 is a dual-specificity protein kinase and Cdc25 is dual-specificity phosphatase. Both control the phosphorylation state of T14 and Y15. Both regulate the cell cycle.
Wee1 needs to be active and phosphorylates Y15 on CDK and inactivate MPF. cells with a defective wee1 gene will prematurely enter mitosis. Wee1 is essential for entry into mitosis.
They regulate mitotic cyclin-CDK by waiting until DNA replication is complete to dephosphorylate CDK1. They not only control CDKs but the activity of the G1 and S phase CDKs.
What are stem cells? What are the advantages and disadvantages of working with embryonic and adult stem cells with respect to stem-cell therapies in humans?
Stem cells are cells that can divide to produce many types of cell; unspecialized cells from which differentiated cells develop. Self-renewal during cell division. There are two kinds of stem cell; embryonic and adult stem cells.
Adult stem cells have less potential for differentiation and are easier to control but embryonic stem cells can divide into any kind of cell.
How does p53 function as a tumor-suppressor protein in response to DNA damage?
p53 will limit cell proliferation.
During mitosis, the breakdown of the nuclear envelope depends on the disassembly of lamin filaments that form a meshwork supporting the membrane. How is that breakdown accomplished?
Phosphorylation of lamins.
The figure below (you need no figure, dumbass) demonstrates that cytoplasm from an egg arrested in M phase of meiosis II can induce an oocyte in G2 to “mature” until it arrests in metaphase of meiosis II. Predict the effect of injecting cytoplasm of that egg (red arrow) into an immature oocyte
\n A)The oocyte would initiate spontaneous mitotic cell cycles \n B) The oocyte would progress to meiosis I. \n C) The oocyte would progress to meiosis II. \n D) The oocyte would die. \n E) The oocyte would remain arrested in G2
C) The oocyte would progress to meiosis II.
Which of the following properties are \n shared by all stem cells? \n A. pluripotent \n B. self-renewal \n C. totipotent \n D. unipotent
B. self-renewal
Phase separation is a term used by physicists to describe condensed matter. Lately, cell biologists have borrowed this term to explain the formation of non-membrane-bound organelles. (1) Explain the concept of liquid-liquid phase separation in the context of cell biology. (2) What is the evidence for liquid-like states in eukaryotic cells? Use an example to answer the second question.
In the context of cell biology, liquid-liquid phase separation is when different biomolecules group up, forming condensed droplet-shaped congregations. This leaves congregated denser molecule groups contrasting against more diluted and less condensed molecule group surroundings.
The evidence for liquid-like states is chemically staining the different biomolecules and microscopically viewing the changes over time. For example, In the nucleus, the Cajal body sub compartment is visualized by staining it's biomolecules with Coilin, the molecules grouping up and forming the droplet shape mentioned above.
Classify each definition as unipotent, multipotent, pluripotent, or totipotent.
Unipotent: cell can differentiate into a single kind of cell \n Multipotent: cell can differentiate into numerous kinds of cells \n Pluripotent: cell can divide into every type of embryonic cell \n Totipotent: cell can divide into every kind of cell
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