biology 1210 chapter 12

How would the removal of growth factors affect asynchronous cultures of (1) normal human cells and (2) most human cancer cells?

(1) Arrest in G1; (2) no effect

What two types of defects does a cancerous cell possess?

Cancerous cells possess defects that make proteins required for cell growth active and tumor suppressor genes inactive.

Which of these phases encompasses all of the stages of mitosis but no other events? The figure shows the pie chart of the cell cycle, which consists of two parts. The bigger part of this pie chart, labeled C, divides into three sectors. The second sector is labeled D. The smaller part of the pie chart divides into two sectors. The first is marked A, the second - B.

E

Which answer correctly identifies a cell-cycle checkpoint with a criterion for passing it?

G2 checkpoint: Chromosomes have replicated successfully.

To which part of the centromere do mitotic spindle fibers attach during prometaphase?

Kinetochore

What would happen if the kinase that adds the inhibitory phosphate to Cdk were defective?

M phase would begin prematurely.

Which event does not take place before the start of mitosis?

The nuclear envelope disintegrates.

What major events occur during anaphase of mitosis?

The sister chromatids of replicated chromosomes separate, and the spindle poles are pushed farther apart.

What role(s) do gap phases play in the cell cycle?

They allow cells to replicate organelles and manufacture additional cytoplasm.

Centromeres divide and sister chromatids become full-fledged chromosomes during _____.

anaphase

During which substage of mitosis do sister chromatids break apart and start moving to opposite poles of the cell?

anaphase

True or false? Mitosis takes place during M phase, which is the longest phase of the cell cycle.

false

_____ is a carcinogen that promotes colon cancer.

fat

Which of these is a carcinogen?

fat UV light cigarette smoke testosterone

During _____ the cell grows and replicates both its organelles and its chromosomes.

interphase

Nucleoli are present during _____.

interphase

The defining characteristic of a malignant tumor is that _____.

its cells can spread to other parts of the body and produce secondary tumors

During which stage of mitosis are chromosomes lined up in the center of the cell?

metaphase

Spindle fibers attach to kinetochores during _____.

prometaphase

Chromosomes become visible during _____.

prophase

Which term describes two recently replicated DNA strands that are joined together just before cell division?

sister chromatids

Cytokinesis often, but not always, accompanies _____.

telophase

Which stage of mitosis is characterized by the disintegration of mitotic spindles and the formation of two new nuclear membranes?

telophase

During _____ both the contents of the nucleus and the cytoplasm are divided.

the mitotic phase

Identify the events in the cell cycle that must be completed successfully for daughter cells to share an identical complement of chromosomes.

the spindle apparatus must connect with the kinetochores of each sister chromatid in prometaphase, all the chromosomes must be replicated during the S phase, the sister chromatids of each replicated chromosome must be partitioned in anaphase and fully separated into daughter cells by cytokinesis

During prophase a homologous pair of chromosomes consists of _____.

two chromosomes and four chromatids