Ch 12.1: The Cell Cycle

Question 1

What occurs during prophase?

Answer 1

The chromatin become tightly coiled into chromosomes, the nucleoli disappear, mitotic spindles begin to form from the aster, and the centrosomes move away from eachother

Question 2

What occurs during prometaphase?

Answer 2

the nuclear envelope fragments, the chromosomes have become even more condensed, microtubules have attached to the kinetochores, and nonkinetochore microtubules interact with those from the opposite pole of the spindle, lengthening the cell

Question 3

What occurs during metaphase?

Answer 3

the centrosomes are now at opposite poles of the cell and the chromosomes have arrived at the metaphase plate

Question 4

What occurs during anaphase?

Answer 4

shortest stage, sister chromosomes are pulled apart and begin moving toward opposite ends of the cell, and the cell elongates as the nonkinetochore microtubules lengthen

Question 5

What occurs during telophase?

Answer 5

two daughter nuclei form in the cell, nuclear envelopes arise from the fragments of the parent cell’s nuclear envelopes, nucleoli reappear, chromosomes become less condensed, and any remaining spindle microtubules are depolymerized

Question 5

What occurs during cytokenisis?

Answer 5

in animal cells, cytokinesis involves that formation of a cleavage furrow, which pinches the cell in two

Question 5

What is a mitotic spindle?

Answer 5

a structure made of microtubules that controls chromosome movement during mitosis

Question 6

What is a centrosome?

Answer 6

a type of microtubule-organizing center where the assembly of spindle microtubules begins

Question 6

When do centrosomes replicate?

Answer 6

during interphase

Question 6

What are kinetochore?

Answer 6

a protein complex associated with centromeres

Question 6

What is the metaphase plate?

Answer 6

an imaginary plane midway between the spindle’s two poles

Question 7

How are microtubules shortened?

Answer 7

motor proteins “walk” or “reel” the chromosomes along the microtubules

Question 7

What forms during cytokinesis for plant cells?

Answer 7

a cell plate

Question 8

How do prokaryotes reproduce?

Answer 8

with binary fission

Question 9

What occurs during binary fission?

Answer 9

the chromosome replicates (beginning at the origin of replication), and then two daughter chromosomes actively move apart, the plasma membrane pinches inward, dividing the cell in two

Question 10

What is the cycle control system?

Answer 10

it directs the events of the cell cycle by both internal and external controls with specific checkpoints where the cell cycle stops until a go-ahead signal is received

Question 11

What are two types of regulatory proteins that are involved in cell cycle control?

Answer 11

cyclins and cyclin-dependent kinases (Cdks)

Question 12

What is a MPF (maturation-promoting factor)?

Answer 12

a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the Mphase

Question 13

What happens if a cell does not receive a go-ahead signal at the G1 checkpoint?

Answer 13

it will exit the cycle, switching into a nondividing state called the G0 phase

Question 14

What are growth factors?

Answer 14

they are released by certain cells and stimulate other cells to divide (external factor)

Question 15

What is density-dependent inhibition?

Answer 15

crowded cells will stop dividing

Question 16

What is anchorage dependence?

Answer 16

for animal cells to divide, they must be attached to a substratum

Question 17

Both density-dependent inhibition and anchorage dependence check:

Answer 17

the growth of cells at an optimal density

Question 18

What happens to a cell that undergoes transformation?

Answer 18

cells now have the ability to divide indefinitely

Question 19

What is a benign tumor?

Answer 19

abnormal cells that remain at the original site

Question 20

What is a malignant tumor?

Answer 20

abnormal cells that invade surrounding tissues

Question 21

What is metastasis?

Answer 21

the spread of cancer cells to other parts of the body, where they may form additional tumors