Which of the following statements about mitosis is incorrect?
A. The daughter nuclei are genetically identical to the parent nucleus.
B. Chromosomes separate during anaphase due to the interaction of polar microtubules from opposite poles pushing against each other.
C. Chromosomes separate during anaphase when the kinetochore microtubules shorten as they depolymerize.
D. Chromosomes move to the metaphase plate using motor proteins, a kind of kinesin, attached to spindle fibers.
Which of the following does not occur during mitosis?
a. condensation of the chromosomes
b. replication of the DNA
c. separation of sister chromatids
d. spindle formation
e. separation of the centrosomes
The mechanism of action of many common medications involves interfering with the normal pathways that cells use to respond to hormone signals. Which of the following best describes a drug interaction that directly interferes with a signal transduction pathway?
A. A medication causes the cell to absorb more of a particular mineral, eventually poisoning the cell.
B. A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger.
C. A medication enters the target cell’s nucleus and acts as a mutagen.
D. A medication interrupts the transcription of ribosomal RNA genes.
B. e. Second messengers are involved in signal transduction pathways, and if the second messenger is not present, the pathway is blocked.
If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be stopped?
A. Anaphase
B. Prophase
C. Telophase
D. Metaphase
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin.
Surprisingly, this stops mitosis. Specifically, taxol must affect
A) the fibers of the mitotic spindle.
B) anaphase.
C) formation of the centrioles.
D) chromatid assembly.
Which of the following is true concerning cancer cells?
A) They do not exhibit density-dependent inhibition when growing in culture.
B) When they stop dividing, they do so at random points in the cell cycle.
C) They are not subject to cell cycle controls.
D) A, B, and C
P53 is a protein that promotes transcription of a gene that suppresses cell division. RAS is a protein that can activate the transcription of proteins that promote cell division. Which of the following is most likely to be found in a cancerous cell?
A. High activity levels of both P53 and RAS
B. High activity levels of P63 and the absence of RAS.
C. High activity levels of RAS and the absence of P53.
D. The absence of both P53 and RAS.