Cell Cycle (Control of cell division)

Question 1

Three fundamental processes determining organ and body size

Answer 1

1. Cell Growth
2. Cell Division
3. Cell Survival

Question 2

Extracellular signal molecules that regulate cell growth, division and survival

Answer 2

Mitogens
Growth factors
Survival factors

Question 3

secreted proteins, proteins bound to the surface of cells, or components of the extracellular matrix

Answer 3

extracellular signal molecules

Question 4

stimulate cell division; G1/S-Cdk activity

Answer 4

Mitogens

Question 5

stimulate cell growth; synthesis of proteins and other macromolecules

Answer 5

growth factors

Question 6

promote cell survival; suppressing apoptosis

Answer 6

Survival factors

Question 7

cell proliferation means?

Answer 7

cell growth

Question 8

Their rate of proliferation depends on the availability of nutrients

Answer 8

unicellular organisms

Question 9

They divide only when the organism needs more cells

Answer 9

multicellular organisms

Question 10

anima cell receive stimulatory extracellular signals in the form of _____ to proliferate

Answer 10

mitogens

Question 11

-first mitogen identified; observation that fibroblasts in a culture dish proliferate when provided with serum not when provided with plasma.
-stimulate many types of cells to divide (fibroblast, smooth muscle cells, neuroglial cells).

Answer 11

Platelet-derived growth factor (PDGF)

Question 12

acts not only on epidermal cells but also on many other cell types, including both epithelial and nonepithelial cells

Answer 12

epidermal growth factor (EGF)

Question 13

only induces the proliferation of red blood cell precursors

Answer 13

erythropoietin

Question 14

inhibitory extracellular signal protein; inhibit proliferation

Answer 14

transforming growth factor-B (TGFB) B for beta

Question 15

Cdk inhibition in G1 is maintained. by the multiple machanisms discussed, and progression into a new cell cycle is blocked.

Answer 15

absence of a mitogenic signal

Question 16

specialized nondividing state

Answer 16

G0

Question 17

neurons and skeletal muscles; cell-cycle control system is completely dismantled

Answer 17

terminally differentiated G0 state

Question 18

the expression of the genes encoding various Cdks and cyclins is permanently ______ ___, and cell division rarely occurs

Answer 18

turned off

Question 19

mitogens control the rate of cell division by acting in the __ _____ of the cell cycle

Answer 19

G1 phase

Question 20

Mitogens interact with cell-surface receptors to trigger?

Answer 20

multiple intracellular signaling pathways

Question 21

One major pathway acts through the monomeric GTPase Ras, which leads to the activation of a?

Answer 21

mitogen-activated protein kinase (MAP kinase) cascade.

Question 22

the activation of mitogen-activated protein kinase (MAP kinase) leads to an increase in the production of?

Answer 22

transcription regulatory proteins, including Myc

Question 23

Myc is thought to promote cell-cycle entry by several mechanisms, one of which is to increase the expression of genes encoding __ ______

Answer 23

G1 cyclins (G1 Cdk)

Question 24

bind to specific DNA sequences in the promoters of a wide variety of genes that encode proteins required for S-phase entry

Answer 24

E2F proteins

Question 25

In the absence of mitogenic stimulation, E2F-dependent gene expression is inhibited by an interaction between E2F and members of the ______________ _______ (Rb) family.

Answer 25

retinoblastoma protein

Question 26

a result of spontaneous chemical reactions in DNA, errors in DNA replication, or exposure to radiation or certain chemicals

Answer 26

DNA damage

Question 27

cell-cycle control detects DNA damage and arrest the cycle

Answer 27

Start and G2/M transition

Question 28

DNA damage initiates a signaling pathway by activating one of a pair of related protein kinases called ___ and ___.

Answer 28

ATM and ATR

Question 29

ATM and ATR associate with the site of damage and phosphorylate various target proteins, including two other protein kinases called ____ and ____.

Answer 29

Chk1 and Chk2

Question 30

stimulates transcription of gene encoding p21

Answer 30

p53

Question 31

binds to G1/S-Cdk and S-Cdk complexes and inhibit their activities, thereby helping to block entry into the cell cycle.

Answer 31

p21

Question 32

undamaged cell, p53 is highly unstable and is present at very ___ _____________

Answer 32

low concentration

Question 33

acts as ubiquitin ligase that targets p53 for destruction

Answer 33

Mdm2

Question 34

Chk1 and Chk2 phosphorylates Cdc25 family of _______ __________

Answer 34

protein phosphatases

Question 35

The DNA damage response can also be activated by problems that arise when a replication fork fails during ___ ___________

Answer 35

DNA replication

Question 36

___ _____ of DNA damage occurs in the normal life of any cell

Answer 36

low level

Question 37

accumulation of genetic damage in cells lacking the DNA damage response leads to an increased frequency of ______-_________ _________

Answer 37

cancer-promoting mutations

Question 38

allows the cancer cell to accumulate mutations more easily

Answer 38

mutations in the p53 gene

Question 39

defect in ATM; very sensitive to x-rays and suffer from increased rates of cancer

Answer 39

ataxia telangiectasia

Question 40

Many human cells divide a limited number of times before they stop and undergo a permanent ____ _____ ______.

Answer 40

cell cycle arrest

Question 41

proliferation slows down and finally halts, and the cells enter a nondividing state from which they never recover

Answer 41

replicative cell senescence

Question 42

Replicative cell senescence in human fibroblasts seems to be caused by changes in the structure of the _________.

Answer 42

Telomeres

Question 43

-the repetitive DNA sequences and associated proteins at the ends of chromosomes.
-promotes the formation of protein cap structures that protects the chromosome ends.

Answer 43

Telomeres

Question 44

constant stimulation of Ras-dependent signaling pathways

Answer 44

mutation in GTPase Ras amino acid

Question 45

overexpression of Myc stimulate excessive ____ ______ and _____________

Answer 45

cell growth and proliferation

Question 46

excessive mitogenic stimulation

Answer 46

production of Arf (cc inhibitor protein)

Question 47

production of Arf (cc inhibitor protein)

Answer 47

inhibits Mdm2

Question 48

inhibits Mdm2

Answer 48

p53 levels increase

Question 49

p53 levels increase

Answer 49

cell-cycle arrest or apoptosis

Question 50

cell growth accompanies ____ _______

Answer 50

cell division

Question 51

stimulate the accumulation of proteins and other macromolecules

Answer 51

increase rate of synthesis and decrease rate of degradation

Question 52

activation of a kinase TOR

Answer 52

phosphoinositide 3-kinase (PI 3-kinase)

Question 53

activates many targets in the cell that stimulate metabolic processes

Answer 53

activation of a kinase TOR

Question 54

S6K

Answer 54

S6 kinase

Question 55

translation initiation factor

Answer 55

elF4E

Question 56

describe a factor that has any of these activities

Answer 56

growth factor

Question 57

withdraw from the cell cycle and re-enter the cycle when damage

Answer 57

Liver cells

Question 58

do not produce telomerase, their telomeres become shorter with every cell
division, and their protective protein caps progressively deteriorate

Answer 58

human fibroblasts

Question 59

the exposed chromosome ends are sensed as DNA damage, which activate

Answer 59

p53-dependent cell-cycle arrest (

Question 60

have regained the ability to produce telomerase and therefore maintain telomere
function as they proliferate

Answer 60

cancer cells

Question 61

mitogenic signaling pathways are encoded by genes
that were originally identified as

Answer 61

cancer-promoting genes