Unit 4: Cell Communication and the Cell Cycle

Based on the results, which mutation most likely disrupts signal transduction rather than signal reception?

If Cell Line C were treated with a drug that permanently activates the kinase in the relay cascade (regardless of receptor binding), the most likely outcome would be

Cell Line D shows normal receptor binding but no increase in cell division. Which step of the signaling pathway is most likely defective?

In the normal signaling pathway (Cell Line A), the growth factor functions as a

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

A cell that is no longer dividing and has exited the cell cycle is said to be in

The p53 protein is a tumor suppressor that can halt the cell cycle at the G₁/S checkpoint. If a mutation inactivates both copies of the p53 gene, the most likely consequence would be

Cyclin-dependent kinases (Cdks) drive the cell cycle forward. Which of the following best explains why Cdk activity fluctuates during the cell cycle?

Which of the following is an example of autocrine signaling?

Apoptosis (programmed cell death) differs from necrosis in that apoptosis

A researcher treats cells with a drug that prevents the formation of the mitotic spindle. The cells would most likely arrest in which phase?

Which of the following best describes the role of second messengers in signal transduction?

During mitosis, sister chromatids separate during which phase?

Based on the data, which characteristic best distinguishes cancer cells from normal cells in this experiment?

The cancer cells most likely have a mutation affecting which of the following regulatory mechanisms?

What is the approximate doubling time (in days) of the normal cells during their exponential growth phase (Days 0-6)?

Which of the following best describes the difference between a proto-oncogene and a tumor suppressor gene?

Which of the following is an example of paracrine signaling?

A mutation in the Ras protein causes it to remain permanently in its active (GTP-bound) state. This would most likely result in

Based on the data, during which phase of the cell cycle do onion root tip cells spend the most time?

The student's data can be used to estimate the relative duration of each phase because

If the total cell cycle for onion root tip cells takes 24 hours, approximately how many hours do cells spend in prophase based on the data? Express as a decimal rounded to one decimal place.

Which checkpoint ensures all chromosomes are properly attached to spindle fibers before the cell proceeds to anaphase?

In the signal transduction pathway, the binding of a ligand to a G-protein-coupled receptor (GPCR) leads to

Apoptosis is important for normal development because it

A researcher discovers a mutation in a gene encoding a Ras protein that prevents GTP hydrolysis. This mutation would most likely result in

The role of cyclin-dependent kinases (Cdks) in the cell cycle is to

During which phase of mitosis do chromosomes line up along the cell's equatorial plate?

Density-dependent inhibition of cell growth refers to the phenomenon where

Which of the following correctly describes the relationship between proto-oncogenes and tumor suppressors?

Which second messenger is produced when adenylyl cyclase is activated?

Signal amplification in a transduction pathway means that

A cell has a mutation in its Rb (retinoblastoma) gene that produces a nonfunctional Rb protein. This cell would most likely

Quorum sensing in bacteria is an example of

A somatic cell has 46 chromosomes. After completing mitosis, how many chromosomes does each daughter cell contain? Express as a whole number.

A cancer cell line is found to have a loss-of-function mutation in the p53 gene. Which cellular process would most directly be impaired?

In a signal transduction pathway, a single hormone molecule binding to a membrane receptor can ultimately activate thousands of downstream effector molecules. This phenomenon is called: