The Cell Cycle: Chp 12

Question 1

cell cycle

Answer 1

the life of a cell from the time it is first formed from a dividing parent cell until its own division into two cells

Question 2

genome

Answer 2

the cells genetic information

Question 3

somatic cells

Answer 3

all body cells except gametes (they have 46 chromosomes)

Question 4

mitosis

Answer 4

the process by which somatic cells divide, forming daughter cells that contain the same chromosome number as the parent cell

Question 5

gametes

Answer 5

sperm and egg cells (haploid). they go through meiosis

Question 6

sister chromatids

Answer 6

there are 2 and they are each of the duplicated chromosomes when they are attached

Question 7

centromere

Answer 7

where the two sister chromatids attach

Question 8

mitosis

Answer 8

the division of the cell’s nucleus (1 cell turns to 2)

Question 9

cytokinesis

Answer 9

the division of the cells cytoplasm

Question 10

interphase

Answer 10

90% of the cell cycle that consists of G1, S, and G2 phases

Question 11

G1 phase

Answer 11

first portion of interphase. the cell grows while carrying out cell functions unique to its cell type

Question 12

S phase

Answer 12

second portion of interphase. the cell continues to carry out its unique functions but does one other important process-it duplicates its chromosomes meaning it makes a copy of DNA that makses up the cells chromosomes

Question 13

G2 phase

Answer 13

the last portion of interphase. the gap after the chromosomes have been duplicated and just before mitosis

Question 14

prophase

Answer 14

1: the chromatin becomes more tightly coiled into discrete chromosomes
2: the nucleoli disappears
3: the mitotic spindle begins to form in the cytoplasm

Question 15

premetaphase

Answer 15

1: the nuclear envelope begins to fragment, allowing the microtubules to attach ot the chromosomes
2: the two chromatids of each chromosome are held together by protein kinetochores in the centromere region
3: the microtubules will attach to the kinetochores

Question 16

metaphase

Answer 16

1: the microtubules move the chromosomes to the metaphase plate at the equator of the cell. the microtubule complex is referred to as the spindle.
2: the centrioles have migrated to opposite poles in the cell, riding along on the developing spindle

Question 17

anaphase

Answer 17

1: sister chromatids begin to separate, pulled apart by motor molecules interacting with kinetochore microtubules
2: the cell elongates, as the nonkinetochore microtubules ratchet apart, again with the help of motor molecules
3: by the end of anaphase, the opposite ends of the cell both contain complete and equal sets of chromosomes

Question 18

telophase

Answer 18

1: the nuclear envelopes re-form around the sets of chromosomes located at opposite ends of the cell
2: the chromatin fiber of the chromosomes becomes less condensed
3: cytokinsesis begins, which is where the cytoplasm of the cell is divided. In animal cells, a cleavage furrow forms and divides. in a plant cell, a cell plate forms that divides the cytoplasm
4: prokaryotes replicate their genome by binary fission rather than mitosis

Question 19

cell cycle control system

Answer 19

this controls the steps of the cycle. It moves the cell through stages by a series of checkpoints where signals tell the cell to either continue dividing or stop.

Question 20

The major cell checkpoints

Answer 20

G1 phase checkpoint, G2 phase checkpoint, and M phase checkpoint

Question 21

G1 phase checkpoint

Answer 21

seems the most important. if the cell gets the go-ahead signal, it usually completes the whole cell cycle and divides. If it does not receive the signal, it enters a nondividing phase called the G0 phase

Question 22

kinases

Answer 22

the protein enzymes that control the cell cycle. they exist in the cells at all times but are active only when they are connected to cyclin protein; thus, they are called cyclin-dependent kinases

Question 23

denisty dependent inhibition

Answer 23

the phenomenon in which crowded cells stop dividing

Question 24

anchorage dependency

Answer 24

normal cells must be attached to a substrate tum, like the extracellular matrix of a tissue, to divide

Question 25

transformation

Answer 25

the process that converts a normal cell to a cancer cell

Question 26

tumor

Answer 26

a mass of abnormal cells wihtin otherwise normal tissue

Question 27

benign tumor

Answer 27

if the abnormal cells remain at the original site

Question 28

malignant tumor

Answer 28

becomes invasive enough to impair the functions of one or more organs. it is also said that it is cancer

Question 29

metastasis

Answer 29

occurs when cells separate from a malignant tumor and enter blood or lymph vessels and travel to other parts of the body