6) Which of the following does NOT happen during M-phase of mitosis? Nuclear env

Question

6) Which of the following does NOT happen during M-phase of mitosis?

Nuclear envelope breakdown

Nuclear envelope reformation

Separation of homologous chromosomes

Separation of sister chromatids

7) Which of the following types of mutations would be most likely to contribute to uncontrolled proliferation of cells?

One that increases the affinity of p21 for Cdks

One that decreases the affinity of Rb for E7 from human papillomavirus

One that decreases the affinity of Rb for the transcription factor E2F

One that causes p53 to be constitutively phosphorylated

8) A chemotherapy drug such as herceptin, which is used to treat certain types of breast cancer, that inhibits the kinase activity of growth factor receptors specifically prevents progression through which cell cycle checkpoint?

G1/S

G2/M

Spindle assembly

None of the above

9) If you inhibit microtubule depolymerization in an actively dividing cell at the beginning of M-phase, what would you observe?

The chromosomes would fail to condense.

The mitotic spindle would fail to form

The chromosomes would fail to align.

The chromosomes would fail to segregate into the daughter cells.

All of the above

10) The structure in animal cells that serves as the primary microtubule organizing center (MTOC), is duplicated during mitosis, and is responsible for seeding microtubules necessary for creation of the mitotic spindle is the _______. (Know all of these terms!)

Centromere

Centriole

Centrosome

Chromatid

Kinetochore

Explanation / Answer

6) Separation of homologous chromosomes

Separation of homologous chromosomes takes place during meoisis I but not in mitosis

7) One that decreases the affinity of Rb for the transcription factor E2F

Rb interacts with E2F to inihibit its activity. once Rb get detached from E2F, it goes and bind to DNA to promote G1/S transition.

8) G1/S

Herceptin increases the levels of p27 resulting in inhibition of CDK2, which results in inhibition of cells from G1 to S phase

9) The chromosomes would fail to segregate into the daughter cells.

polymerisation and depolymerisation of microtubules is required for segregation of chromosomes by kinesin proteins

10) Centriole

it acts as a seeding center and plays a major role in microtubule organisation during cell division

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