1.7 Cytokinesis and Cell Growth Control

Question 1

Cytokinesis is the [ ] in M phase, as well as the cell cycle.

Answer 1

Final step

Question 2

In animal cell, cytokinesis begins in [ ] and ends shortly after [ ].

Answer 2

1. anaphase
2. telophase

Question 3

Telophase begins with appearance of [ ] on the cell surface.

Answer 3

cleavage furrow

Question 4

Cleavage furrow development is the result of the [ ].

Answer 4

contractile ring

Question 5

The contractile ring is made of [ ], as well as structural proteins.

Answer 5

actin & myosin

Question 6

Actin and myosin make up the cell [ ].

Answer 6

cortex (under plasa ebrane)

Question 7

The cell cortex begins to [ ] when the cell enters mitosis.

Answer 7

disassemble

Question 8

During anaphase, actin and myosin reorganize as parallel linear filaments, producing [ ].

Answer 8

contractile ring

Question 9

The filaments of the ring are [ ], with the number of subunits [ ] as the ring constricts.

Answer 9

1. dynamic
2. decreasing

Question 10

Eventually, the cleavage furrow narrows to the point where it fors the structure called the [ ].

Answer 10

midbody, which tethers together the two daughter cells

Question 11

Cytokinesis is completed by [ ], where membranes are [ ] and [ ].

Answer 11

1. abscission
2. constricted
3. severed

Question 12

Assembly of the contractile ring is dependent upon [ ].

Answer 12

RhoA

Question 13

RhoA is attached at the [ ] on the inner cell membrane. Here it promotes the formation of [ ], [ ], and [ ].

Answer 13

1. division site
2. actin filaments
3. myosin activation
4. ring contraction

Question 14

[ ] activates RhoA.

Answer 14

Rho GEF

Question 15

What are the functions of activated RhoA?

Answer 15

1. activates formins
2. activates Rho-associated kinases (ex: ROCK) which promotes myosin assembly and activation

Question 16

What is the right time for cytokinesis?

Answer 16

division occurs only after two sets of chromosomes have segregated from each other

Question 17

What is the right place for cytokinesis?

Answer 17

division occurs between sets of segregating chromosomes

Question 18

[ ] helps determine the timing and placement of cytoplasmic division.

Answer 18

mitotic spindle

Question 19

During anaphase, [ ] initiate furrow formation at the [ ].

Answer 19

1. signals originating from the spindle
2. midway point between spindle poles

Question 20

What is the function of Aurora-B?

Answer 20

localized around the spindle midzone during anaphase. Aurora-B promotes assembly of the centralspindlin dimer.

Question 21

What is the function of centralspindlin?

Answer 21

a key regulatory protein in this process that concentrates around the antiparallel microtubules at the spindle midzone.

Question 22

Centralspindlin promotes the [ ].

Answer 22

activation of RhoA through Rho GEF (Ect2)

Question 23

Astral microtubules are able to [ ].

Answer 23

prevent centralspindlin outside of equatorial region

Question 24

Other organelles, such as mitochrondria, ER, and chloroplasts require [ ].

Answer 24

replication from pre-existing organelles

Question 25

Some organelles, like mitochrondria, are produced in [ ].

Answer 25

large numbers

Question 26

In cytokinesis, the ER is [ ], and daughter cells inherit a [ ].

Answer 26

1. broken down 2. portion

Question 27

Golgi is [ ] during mitosis. [ ] associate with [ ], and are then [ ] by daughter cells.

Answer 27

1. fragmented 2. 2. fragments 3. 3. spindle poles 4. inherited

Question 28

What are the three classes of signal types?

Answer 28

1. mitogens 2. growth factors 3. survival factors

Question 29

Mitogens stimulated [ ]. Primarily work by promoted [ ] activity.

Answer 29

1. cell division 2. C1/S-Cdk activity

Question 30

What are the two factors that influence the rate of cell division?

Answer 30

1. Division of unicellular organisms is more dependent on availability of nutrients 2. Division in multicellular organisms, however, is more complex

Question 31

What are the two characteristics of mitogens?

Answer 31

1. 50+ proteins 2. most with broad specificity, some with narrow specificity

Question 32

When there is an absence of mitogenic signals, [ ] is maintaing in [ ]. It is possible for cells to withdraw from cell cycle entireley into [ ].

Answer 32

1. Cdk inhibition 2. G1 3. specialized non-dividing state called G0.

Question 33

Most cells in our body are in [ ].

Answer 33

G0

Question 34

Neurons and skeletal muscle are in [ ], and cell-cycle control mechanisms are [ ]. Cells rarely undergo mitosis.

Answer 34

1. terminally differentiated G0 state 2. compeltely dismantled

Question 35

Liver cells are normally in [ ]. However, they can [ ] in response to liver damage.

Answer 35

1. G0 state 2. re-enter cell cycle

Question 36

Control over rate of cell division depends on [ ].

Answer 36

mitogen influence on G1 phase

Question 37

What are the three functions of Myc?

Answer 37

1. promote entry into cell cycle through severeal echanisms 2. promote synthesis of G1-cyclins, thereby increasing G-1Cdk activity 3. promote transcription of genes that increase cell growth

Question 38

What is the primary function of G1-Cdk?

Answer 38

to activate E2F gene regulatory proteins

Question 39

E2F proteins bind to [ ] of various genes required for [ ].

Answer 39

1. bind to promoter and promote expression 2. entry into S phase

Question 40

What is the function of feedback loops?

Answer 40

help ensure irreversible activation and entry into the cell cycle

Question 41

A key intracellular regulator of cell division is the [ ].

Answer 41

damage of DNA

Question 42

The cell cycle can detect damage and halt cell cycle at either the [ ] or the [ ].

Answer 42

1. Start Transition 2. G1/Transition

Question 43

[ ] promotes the activation of either the [ ] or [ ].

Answer 43

1. DNA damage 2. ATM 3. ATR Kinase

Question 44

The activated kinase [ ] with the site of [ ] and [ ]. This results in downstream [ ].

Answer 44

1. associates 2. DNA damage 3. phoshporylates target proteins 4. activation of p53

Question 45

What is replicated cell senescence?

Answer 45

many cells have a limited number of replicative cycles before they undergo a permanent cell cycle arrest

Question 46

Senescence appears to be caused by [ ].

Answer 46

a change in telomere structure.

Question 47

What are telomeres?

Answer 47

replicated DNA sequences at the end of chromosomes

Question 48

DNA in telomeres are replicated by [ ], which is involved in the formation of the protein cap.

Answer 48

enzyme telomerase

Question 49

Telomerase is not expressed in [ ]. This causes telomeres to [ ] with every cell cycle.

Answer 49

1. somatic cells 2. shorten

Question 50

Eventual exposure of chromosome ends is recognized as [ ], and triggers [ ] to initiate [ ].

Answer 50

1. DNA damage 2. p53 3. cell cycle arrest

Question 51

Growth factors are [ ] that promote [ ].

Answer 51

1. extracellular signals 2. increases in cellular mass

Question 52

What are the two functions of growth factors?

Answer 52

1. promote synthesis of macromolecules 2. inhibit degradation of macromolecules

Question 53

What is the function of mTORC1?

Answer 53

promotes protein synthesis, lipid synthesis, and decreased protein degradation

Question 54

Rate of growth must ensure [ ].

Answer 54

dividing cells are not too small or too large

Question 55

Size must double through cell cycle to ensure [ ].

Answer 55

consistent cellular mass

Question 56

What are the three mechanisms of coordination of cell growth.

Answer 56

1. single extracellular factor promotes growth, and growth promotes division 2. separate growth factors and mitogens influencing cell growth/division in a cell type 3. extracellular factor simultaneously affects both growth and division

Question 57

Survival factors work by [ ].

Answer 57

surppressing apoptosis