Ch 18 - The Cell-Division Cycle

Question 1

anaphase

Answer 1

stage of mitosis during which the two sets of chromosomes separate and are pulled toward opposite ends of the dividing cell

Question 2

anaphase-promoting complex (APC/C)

Answer 2

a protein complex that triggers the separation of sister chromatids and orchestrates the carefully timed destruction of proteins that control progress through the cell cycle; the complex catalyzes the ubiquitylation of its targets

Question 3

apoptosis

Answer 3

a tightly controlled form of programmed cell death that allows excess cells to be eliminated from an adult or developing organism

Question 4

aster

Answer 4

star-shaped array of microtubules emanating from a centrosome or from a pole of a mitotic spindle

Question 5

Bcl2 family

Answer 5

related group of intracellular proteins that regulates apoptosis; some family members promote cell death, others inhibit it

Question 6

bi-orientation

Answer 6

the symmetrical attachment of a sister-chromatid pair on the mitotic spindle such that one chromatid in the duplicated chromosome is attached to one spindle pole and the other is attached to the opposite pole

Question 7

caspase

Answer 7

one of a family of proteases that, when activated, mediates the destruction of the cell by apoptosis

Question 8

Cdk (cyclin-dependent protein kinase)

Answer 8

enzyme that, when complexed with a regulatory cyclin protein, can trigger various events in the cell-division cycle by phosphorylating specific target proteins

Question 9

Cdk inhibitor protein

Answer 9

regulatory protein that blocks the assembly or activity of cyclin-Cdk complexes, delaying progression primarily through the G1 and S phases of the cell cycle

Question 10

cell cycle

Answer 10

the orderly sequence of events by which a cell duplicates its contents and divides into two

Question 11

cell-cycle control system

Answer 11

network of regulatory proteins that govern the orderly progression of a eukaryotic cell through the stages of cell division

Question 12

centrosome

Answer 12

microtubule-organizing center that sits near the nucleus in an animal cell; during the cell cycle, this structure duplicates to form the two poles of the mitotic spindle

Question 13

centrosome cycle

Answer 13

process by which the centrosome duplicates (during interphase) and the two new centrosomes separate (at the beginning of mitosis) to form the poles o the mitotic spindle

Question 14

chromosome condensation

Answer 14

process by which a duplicated chromosome becomes packed into a more compact structure prior to cell division

Question 15

cohesin

Answer 15

protein complex that holds sister chromatids together after DNA has been replicated in the cell cycle

Question 16

condensin

Answer 16

protein complex that helps configure duplicated chromosomes for segregation by making them more compact

Question 17

contractile ring

Answer 17

structure made of actin and myosin filaments that forms a belt around a dividing cell, pinching it in two

Question 18

cyclin

Answer 18

regulatory protein whose concentration rises and falls at specific times during the eukaryotic cell cycle; cyclins help control progression from one stage of the cell cycle to the next by binding to cyclin-dependent protein kinases (Cdks)

Question 19

cytokinesis

Answer 19

process by which the cytoplasm of a plant or animal cell divides in to to form individual dughter cells

Question 20

G1 cyclin

Answer 20

Regulatory protin that helps drive a cell through the first gap phase of the cell cycle toward S phase

Question 21

G1 phase

Answer 21

Gap 1 phase of the eukaryotic cell cycle; falls between the end of cytokinesis and the start of DNA synthesis

Question 22

G1-Cdk

Answer 22

protein complex whose activity drives the cell through the first gap phase of the cell cycle; consist of a G1 cyclin plus a cyclin-dependent protein kinase (Cdk)

Question 23

G1/S cyclin

Answer 23

regulatory protein that helps to launch the S phase of the cell cycle

Question 24

G1/S-Cdk

Answer 24

protein complex whose activity triggers entry into S phase of the cell cycle; consists of a G1/S cyclin plus a cyclin-dependent protein kinase (Cdk)

Question 25

G2 phase

Answer 25

gap 2 phase of the eukaryotic cell cycle; falls between the end of DNA synthesis and the beginning of mitosis

Question 26

growth factor

Answer 26

extracellular signal molecule that stimulates a cell to increase in size and mass. examples include epidermal growth factor (EGF) and platelet-derived growth factor (PDGF)

Question 27

interphase

Answer 27

long period of the cell cycle between one mitosis and the next. includes G1 phase, S phase and G2 phase

Question 28

kinetochore

Answer 28

protein complex that assembles on the centromere of a condensed mitotic chromosome; the site to which spindle microtubules attach

Question 29

M cyclin

Answer 29

regulatory protein that binds to mitotic Cdk to form M-Cdk, the protein complex that triggers the M phase of the cell cycle

Question 30

M phase

Answer 30

period of the eukaryotic cell cycle during which the nucleus and cytoplasm divide

Question 31

M-Cdk

Answer 31

protein complex that triggers the M phase of the cell cycle; consist of an M cyclin plus a mitotic cyclin-dependent protein kinase (Cdk)

Question 32

metaphase

Answer 32

stage of mitosis in which chromosomes are properly attached to the mitotic spindle at its equator but have not yet segregated toward opposite poles

Question 33

mitogen

Answer 33

an extracellular signal molecule that stimulates cell proliferation

Question 34

mitosis

Answer 34

division of the nucleus of a eukaryotic cell

Question 35

mitotic spindle

Answer 35

array of microtubules and associated molecules that forms between the opposite poles of a eukaryotic cell during mitosis and pulls duplicated chromosome sets apart

Question 36

p53

Answer 36

transcription regulator that controls the cell’s response to DNA damage, preventing the cell from entering S phase until the damage has been repaired or inducing the cell to commit suicide if the damage is too extensive; mutations in the gene encoding this protein are found in many human cancers

Question 37

phragmoplast

Answer 37

in a dividing plant cell, structure made of microtubules and membrane vesicles that guides the formation of a new cell wall

Question 38

programmed cell death

Answer 38

a tightly controlled form of cell suicide that allows cells that are unneeded or unwanted to be eliminated from an adult or developing organism; the major form is called apoptosis

Question 39

prometaphase

Answer 39

stage of mitosis in which the nuclear envelope breaks down and duplicated chromosomes are captured by the spindle microtubules; precedes metaphase

Question 40

prophase

Answer 40

first stage of mitosis, during which the duplicated chromosomes condense and the mitotic spindle forms

Question 41

S cyclin

Answer 41

regulatory protein that helps to launch the S phase of the cell cycle

Question 42

S phase

Answer 42

period during a eukaryotic cell cycle in which DNA is synthesized

Question 43

S-Cdk

Answer 43

protein complex whose activity initiates DNA replication; consists of an S cyclin plus a cyclin-dependent protein kinase (Cdk)

Question 44

sister chromatid

Answer 44

copy of a chromosome, produced by DNA replication, that remains bound to the other copy

Question 45

spindle pole

Answer 45

centrosome from which microtubules radiate to form the mitotic spindle

Question 46

survival factor

Answer 46

extracellular signal molecule that must be present to suppress apoptosis

Question 47

telophase

Answer 47

final stage of mitosis in which the two sets of separated chromosomes decondense and become enclosed by a nuclear envelope)