Chapter 18 Key Terms

Question 1

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

Answer 1

Anaphase

Question 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

Answer 2

Anaphase-promoting complex (APC)

Question 3

A tightly controlled form of programmed cell death that allows cells that are unneeded or unwanted to be eliminated from an adult or developing organism

Answer 3

Apoptosis

Question 4

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

Answer 4

Aster

Question 5

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

Answer 5

Bcl2 family

Question 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.

Answer 6

bi-orientation

Question 7

A family of proteases that, when activated, mediates the destruction of the cell by apoptosis.

Answer 7

caspase

Question 8

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

Answer 8

Cdk (cyclin-dependent protein kinase)

Question 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.

Answer 9

Cdk inhibitor protein

Question 10

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

Answer 10

Cell cycle

Question 11

Network of regulatory proteins that govern the orderly progression of a eukaryotic cel through the stages of cell division.

Answer 11

Cell-cycle control system

Question 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

Answer 12

centrosome

Question 13

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

Answer 13

centrosome cycle

Question 14

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

Answer 14

chromosome condensation

Question 15

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

Answer 15

cohesin

Question 16

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

Answer 16

condensin

Question 17

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

Answer 17

contractile ring

Question 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 cycin-dependent protein kinases (Cdks)

Answer 18

cyclin

Question 19

Process by which the cytoplasm of a plant or animal cell divides in two to form individual daughter cells.

Answer 19

cytokinesis

Question 20

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

Answer 20

G1-Cdk

Question 21

Regulatory protein that helps drive a cell through the first gap phase of the cell cycle and toward S phase.

Answer 21

G1 cyclin

Question 22

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

Answer 22

G1 phase

Question 23

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

Answer 23

G2 phase

Question 24

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

Answer 24

G1/S-Cdk

Question 25

Regulatory protein that helps to launch the S phase of the cell cycle.

Answer 25

G1/S cyclin

Question 26

Extracellular signaling molecule that stimulates a cell to increase in size and mass. Examples include epidermal growth factor (EGF) and platelet-derived growth factor (PDGF)

Answer 26

Growth factor

Question 27

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

Answer 27

interphase

Question 28

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

Answer 28

kinetochore

Question 29

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

Answer 29

M-Cdk

Question 30

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

Answer 30

M cyclin

Question 31

Period of the eukaryotic cell cycle during which the nucleus and cytoplasm divide.

Answer 31

M phase

Question 32

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

Answer 32

Metaphase

Question 33

An extracellular signal molecule that stimulates cell proliferation.

Answer 33

mitogen

Question 34

Division of the nucleus of a eukaryotic cell.

Answer 34

mitosis

Question 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.

Answer 35

mitotic spindle

Question 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.

Answer 36

p53

Question 37

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

Answer 37

phragmoplast

Question 38

A tightly controlled form of cell suicide that allows cells that are unneeded for or unwanted to be eliminated from an adult or developing organism; also called apoptosis.

Answer 38

programmed cell death

Question 39

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

Answer 39

prometaphase

Question 40

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

Answer 40

S-Cdk

Question 41

Regulatory protein that helps to launch the S phase of the cell cycle.

Answer 41

S cyclin

Question 42

Period during a eukaryotic cell cycle in which DNA is synthesized.

Answer 42

S phase

Question 43

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

Answer 43

sister chromatid

Question 44

Centrosome from which microtubules radiate to form the mitotic spindle.

Answer 44

spindle pole

Question 45

Extracellular signal molecule that must be present to suppress apoptosis.

Answer 45

survival factor

Question 46

Final stage of mitosis in which the two sets of separated chromosomes de-condense and become enclosed by a nuclear envelope.

Answer 46

telophase

Question 47

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

Answer 47

Prophase