Cell Cycle 1

Question 1

What happens in cell reproduction?

Answer 1

duplication of contents of cell (chromosomes and organelles)

divide cell into two (cytokinesis)

Question 2

What are the three major functional aspects of the cell cycle?

Answer 2

1. cell growth and chromosome replication
2. chromosome segregation
3. cell division

Question 3

What is the goal of the cell cycle?

Answer 3

produce two genetically identical daughter cells

Question 4

How often do mistakes occur in the cell cycle?

Answer 4

rate of 1 x 10^-9 per replication

6 mistakes occur in one cell division

Question 5

Cancer is a disease of excess cell _______

Answer 5

proliferation

Question 6

Chromosome duplication is in the ___ phase of cell cycle

Answer 6

S

Question 7

Chromosome segregation and cell division occur during ____ phase of cell cycle

Answer 7

M

Question 8

What is cytokinesis?

Answer 8

cell division

Question 9

What occurs during prophase?

Answer 9

chromosomes condense into rigid rods called sister chromatids (become attached to mitotic spindle: a bipolar array of microtubules)

Question 10

What occurs during metaphase?

Answer 10

sister chromatids line up at equator of cell attached to opposite poles of spindle

Question 11

What occurs during anaphase?

Answer 11

sister chromatids become daughter chromosomes and are pulled to opposite poles of spindle

Question 12

What occurs during telophase?

Answer 12

spindle disassembles, chromosomes packaged into separate nuclei, cytokinesis occurs

Question 13

What are the GAP phases?

Answer 13

phases which allow for more time to grow

Question 14

When does G1 phase occur?

Answer 14

between M and S

Question 15

When does G2 phase occur?

Answer 15

between S and M

Question 16

Describe checkpoint 1

Answer 16

Start, cell commits cycle entry and chromosome duplication

Question 17

Describe checkpont 2

Answer 17

G2/M- chromosome alignment on spindle in metaphase

Question 18

Describe checkpoint 3

Answer 18

metaphase to anaphase transition- trigger sister chromatid separation and cytokinesis

Question 19

Describe fission yeast

Answer 19

grows by elongation at ends; division occurs when septum or cell plate form midway along rod shaped cell

Question 20

Describe budding yeast

Answer 20

oval yeast that divides by forming a bud; the bud first appears at G1 and grows until mitosis phase

Question 21

What are immortalized cell lines?

Answer 21

cell lines grow forever

Question 22

What do cyclin dependent kinases (Cdks) do?

Answer 22

phosphorylate proteins downstream to activate them and regulate cell cycle events

Question 23

What are the proteins that regulate Cdks?

Answer 23

cyclins

Question 24

Cdks must be _____ to cyclin to have protein kinase activity

Answer 24

bound

Question 25

Are Cdk levels constant?

Answer 25

yes, only cyclin levels vary

Question 26

What do G1/S cyclins do?

Answer 26

start cell cycle by activating Cdks in late G1

Question 27

What do S cyclins do?

Answer 27

duplicate DNA

Question 28

What do M cyclins do?

Answer 28

mitosis

Question 29

______ of Cdks rise and fall during cell cycle | ________ of cyclins rise and rall

Answer 29

activities; levels

Question 30

When binding cyclin to Cdk, what happens to the t-loop?

Answer 30

it moves out of the active site and phosphorylation occurs, allowing for fully activated enzyme

Question 31

How does Wee1 kinase inhibit Cdk activity?

Answer 31

by phosphorylating the roof site

Question 32

How does Cdc25 increase Cdk activity?

Answer 32

It is a phosphatase that dephosphorylates roof site to increase activity

Question 33

What are CKI proteins?

Answer 33

Cdk inhibitory proteins that causes cyclin-Cdk complex to be inhibited

Question 34

What is INK4A?

Answer 34

CKI involved in G1 phase of cell cycle

Question 35

_____ occurs in INK4A gene in hereditary melanoma. Which results in what?

Answer 35

mutation | cannot control cell cycle and cells grow uncontrollably and you get cancer

Question 36

What is p53?

Answer 36

a major tumor suppressor

Question 37

What does p53 do to p21?

Answer 37

up regulates it

Question 38

What is p21?

Answer 38

CKI to stop cell division

Question 39

What happens when there is a fail in function for p53?

Answer 39

lower p21 expression and without this CKI cells divide uncontrollably-- cancer

Question 40

Proteolysis of CKI's can turn on ______

Answer 40

S-Cdk's

Question 41

What controls mitosis?

Answer 41

M-Cdk

Question 42

What is the inactive form of m-cdk?

Answer 42

cyclin-M cdk complex

Question 43

What holds M-cdk in inactive state?

Answer 43

Wee1

Question 44

activation of primed M-cdk is by _____

Answer 44

Cdc25 protein phosphatase

Question 45

What two proteins affect the APC/C system?

Answer 45

cohesin and securin

Question 46

What does cohesin do?

Answer 46

glue sister chromatids together by their length

Question 47

What does securin do?

Answer 47

protects cohesion protein linkages that hold sister chromatid pairs together in early mitosis

Question 48

Securin ______ cohesins

Answer 48

protects

Question 49

How does securin protect cohesin?

Answer 49

inhibiting a protein called separate, an enzyme that cleaves cohesin