Question 1

Which of the following best describes the role of cyclin-dependent kinases (Cdks) in the regulation of the cell cycle?

Accepted Answer

Cdks phosphorylate target proteins only when bound to cyclins, regulating progression through cell cycle checkpoints.

Question 2

A mutation causes the anaphase-promoting complex (APC) to be nonfunctional in a cell. What is the most likely consequence?

Accepted Answer

Sister chromatids will not separate, and the cell will fail to exit mitosis.

Question 3

Which of the following statements about G-protein signaling is correct?

Accepted Answer

Phospholipase C cleaves a lipid to produce DAG and IP3, which act as second messengers.

Question 4

During which phase of mitosis do chromosomes align at the metaphase plate, and what is the significance of this alignment?

Accepted Answer

Metaphase; it ensures that each daughter cell receives one copy of each chromosome.

Question 5

A researcher uses colchicine to treat dividing cells. What is the expected effect, and why is this useful in karyotyping?

Accepted Answer

Cells are arrested in metaphase, making chromosomes most visible for analysis.

Question 6

Which of the following best explains the difference between cis-acting and trans-acting elements in gene regulation?

Accepted Answer

Cis-acting elements are DNA sequences near the gene they regulate; trans-acting elements are usually diffusible molecules like proteins.

Question 7

Which event marks the transition from G2 phase to M phase in the cell cycle?

Accepted Answer

Activation of mitotic Cdk-cyclin complex once sufficient cyclin is present.

Question 8

A cell is observed to have condensed chromosomes, a disappearing nucleolus, and centrosomes migrating apart. Which phase is this cell in?

Accepted Answer

Prophase

Question 9

Which of the following best describes the function of the restriction point (G1-S transition) in the cell cycle?

Accepted Answer

It commits the cell to DNA synthesis and subsequent division if passed.

Question 10

In G-protein signaling, what is the role of IP3 after it is produced by phospholipase C?

Accepted Answer

It binds to and opens calcium channels in the endoplasmic reticulum.

Question 11

Which of the following omics methods would be most appropriate for identifying all the proteins expressed in a cancer cell line?

Accepted Answer

Proteomics

Question 12

A neuron is unable to generate an action potential. Which of the following is most likely defective?

Accepted Answer

Voltage-gated sodium channels

Question 13

Which checkpoint ensures that all chromosomes are properly attached to the spindle before sister chromatids separate?

Accepted Answer

Metaphase-anaphase checkpoint

Question 14

Which of the following best describes the difference between mitosis and meiosis?

Accepted Answer

Mitosis results in genetically identical daughter cells, while meiosis produces genetically diverse gametes.

Question 15

A scientist wants to manipulate gene expression in a eukaryotic cell. Which method would allow her to specifically reduce the expression of a target gene?

Accepted Answer

RNA interference (RNAi)

Question 16

Which of the following is a direct downstream effect of increased cytoplasmic calcium following G-protein signaling?

Accepted Answer

Activation of calmodulin and a protein kinase cascade

Question 17

During which phase of the cell cycle does DNA replication occur?

Accepted Answer

S phase

Question 18

Which of the following best explains why mature nerve and muscle cells do not divide?

Accepted Answer

They are arrested in the G0 phase and have undergone terminal differentiation.

Question 19

A cell is observed to have two nuclei but only one cytoplasm. Which process has failed to occur?

Accepted Answer

Cytokinesis

Question 20

Which of the following equations best represents the change in membrane potential during an action potential?

Accepted Answer

$$\Delta V_m = V_{peak} - V_{rest}$$

Cell Biology Study Guide: Gene Regulation, Signal Transduction, Action Potentials, and the Cell Cycle

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