Exam 4: Cell Division

Question 1

3 Roles of Cell Division

Answer 1

1. Reproduction
2. Growth/development
3. Tissue renewal/regeneration

Question 2

What does a chromosome contain?

Answer 2

A single double helix of deoxyribonucleic acid wrapped around proteins

Question 3

Where are chromatids joined at?

Answer 3

The centromere

Question 4

What are sister chromatids?

Answer 4

Chromatids from the same chromosome

Question 5

Is interphase dividing or non-dividing?

Answer 5

Non-dividing

Question 6

Is M phase dividing or non-dividing?

Answer 6

Dividing

Question 7

What does M phase stand for?

Answer 7

Mitotic phase

Question 8

What are the two gap phases?

Answer 8

G1 and G2

Question 9

What are the four phases of the cell cycle?

Answer 9

M phase, interphase (which consists of G1, S, and G2)

Question 10

What are the three purposes of the gap phases?

Answer 10

1. Cell grows enough
2. Synthesize enough organelles
3. Ensure the cell has normal size and function

Question 11

What happens in G1 phase?

Answer 11

There are 4 unreplicated chromosomes

Question 12

What happens in S phase?

Answer 12

Duplicated DNA is rearranged through cohesion to form sister chromatids

Question 13

What attaches the sister chromatids in S phase?

Answer 13

Cohesins

Question 14

What happens in G2 phase?

Answer 14

There are four replicated chromosomes

Question 15

How many sister chromatids are there in G2 phase?

Answer 15

2 per replicated chromosome, so 8 total

Question 16

What are the phases of mitosis in order?

Answer 16

PPMAT (prophase, prometaphase, metaphase, anaphase, telophase

Question 17

What happens in prophase?

Answer 17

The chromosomes condense and the spindle apparatus begins to form

Question 18

What happens in prometaphase?

Answer 18

The nuclear envelope breaks down, microtubules contact kinetochores

Question 19

What happens in metaphase?

Answer 19

The chromosomes complete migration to the middle of the cell

Question 20

What happens in anaphase?

Answer 20

Sister chromatids are separated and pulled apart

Question 21

What are the separated sister chromatids called after they are pulled apart in anaphase?

Answer 21

Daughter chromosomes

Question 22

What happens in telophase?

Answer 22

The nuclear envelope re-forms, the chromosomes de-condense

Question 23

When does cell division occur?

Answer 23

During cytokinesis

Question 24

What causes the plasma membrane in cytokinesis to pinch in?

Answer 24

Actin-myosin ring

Question 25

What are microtubules formed from?

Answer 25

tubulin proteins

Question 26

What are the the three types of microtubules?

Answer 26

Astral, polar, kinetochore

Question 27

What do astral microtubules do?

Answer 27

They position spindle in the cell

Question 28

What do polar microtubules do?

Answer 28

They separate two poles

Question 29

Where are kinetochore microtubules?

Answer 29

They are attached to kinetochores which are bound to centromeres

Question 30

What moves chromosomes during mitosis?

Answer 30

Kinetochore microtubules
- + ends depolymerize/fray, and the expansion forces the kinetochore ring ring and attached chromosome towards the minus end of the microtubule.

Question 31

How does cytokinesis occur in plants?

Answer 31

Microtubules direct vesicles toward the center of spindle where they fuse to divide the cell into two

Question 32

What are the four components of the G1 checkpoint?

Answer 32

1. Cell size is adequate
2. Nutrients are sufficient
3. Social signals are present
4. DNA is undamaged

Question 33

Where do cells that pass the G1 checkpoint go?

Answer 33

S stage

Question 34

Where do cells that fail the G1 checkpoint go?

Answer 34

G0 state

Question 35

What are the three components of the G2 checkpoint?

Answer 35

1. Chromosomes have replicated
2. DNA is undamaged
3. Activated mitosis-promoting factor is present

Question 36

What are the three components of the Mitosis checkpoint?

Answer 36

1. chromosomes have attached to spindle apparatus
2. chromosomes have separated
3. MPF is absent/deactivated

Question 37

What does MPF consist of?

Answer 37

Cyclin, Cdk, P

Question 38

How does MPF work?

Answer 38

Cyclin-dependent kinase catalyzes phosphorylation of other proteins

Question 39

Which phase does MPF start?

Answer 39

Mitosis

Question 40

When is MPF component concentration highest?

Answer 40

Beginning of mitosis

Question 41

When is MPF component concentration lowest?

Answer 41

End of mitosis

Question 42

What type of control is G1 subject to?

Answer 42

Social control

Question 43

What is the first step of social control?

Answer 43

Growth factors arrive from other cells

Question 44

What is the second step of social control?

Answer 44

Growth factors cause increase in cyclin and E2F concentrations

Question 45

What is the third step of social control?

Answer 45

Cyclin binds to Cdk; Cdk is phosphorylated. Rb inactivates
E2F by binding to it.

Question 46

What is the fourth step of social control?

Answer 46

Inactivating phosphate is removed, and active Cdk
phosphorylates Rb.

Question 47

What is the fifth step of social control?

Answer 47

Phosphorylated Rb releases E2F

Question 48

What is the sixth step of social control?

Answer 48

E2F triggers production of S-phase proteins

Question 49

When are cells subject to mitogenic growth factors?

Answer 49

G1 phase

Question 50

What promotes cell division under normal conditions?

Answer 50

Proto-oncogenes

Question 51

What are two examples of an proto-oncogene?

Answer 51

Ras, EGFR

Question 52

What inhibits cell cycle progression?

Answer 52

Tumor suppressors

Question 53

What are two examples of tumor suppressors?

Answer 53

P53, Rb

Question 54

What senses DNA damage and other problems?

Answer 54

P53

Question 55

If DNA is damaged, what are the three ways to go?

Answer 55

1. Cell cycle transitions
2. Apoptosis
3. DNA repair