Mitosis and the Cell Cycle LO Flashcards Preview

M2M Biochemistry and molecular biology > Mitosis and the Cell Cycle LO > Flashcards

Flashcards in Mitosis and the Cell Cycle LO Deck (48):
1

what is the point of the restriction point (R)?

cell must be large enough to move to the next stage (S)

2

What happens once the cell passes the R phase?

cell is committed to cell cycle

3

what is the main goal of somatic cell cycle?

ensure exact duplication of genome in S phase followed by exact division of genome in M phase to produce identical daughter cells

4

how is regulation accomplished throughout the cell cycle?

variation in cyclin concentrations regulate activation of CDKs which in turn regulate formation of pre-replication complex (pre-RC)

5

what is the level of CDK at start of G1?

low to allow formation of pre-replication complex (pre-RC)

6

what is level of CDK activity at S?

high, allows activation of pre-RC

7

what does high CDK activity do to pre-RC formation?

blocks it

8

what is the level of CDK in M phase?

high, to allow for cell replication

9

what does chromosome re-replication complexes in S phase or mis-segregation during mitosis produce?

cancer and birth defects

10

what is aneuploidy?

incorrect number of chromosomes in a cell

11

what is the difference between mitosis and meiosis in regards to the numbers and types of cells created?

mitosis = 2 identical diploid cells
meiosis = 4 non-identical haploid cells

12

what are the 6 phases of mitosis?

1. interphase
2. prophase
3. metaphase
4. anaphase
5. telophase
6. cytokinesis

13

what occurs during interphase?

cell growth

14

what occurs during prophase?

chromatin condenses

15

what occurs during metaphase?

chromosome line up at metaphase plate

16

what occurs during anaphase

sister chromatids separate and are pulled to opposite ends of cell

17

what occurs during telophase?

new nuclear membrane surrounds each sister chromatid

18

what occurs during cytokinesis?

cell divides into 2 diploid cells

19

what occurs in meiotic prophase?

chromosomes replicate resulting in 2 homologous chromosomes

20

when does crossing over take place?

during meiotic prophase when sister chromatids are formed

21

what occurs during meiosis I?

homologs are separated into 2 cells (reductional division)

22

what occurs during meiosis II?

each pair of sister chromatids separated into different cells resulting in 4 haploid cells (equational division)

23

what types of cells are stuck in the R point of the cell cycle?

neurons, and then continue to grow without entering the cell cycle

24

what is a CDK?

cyclin-dependent kinase

25

what are CDK's activated by?

cyclins

26

what are CDK's inhibited by?

Cip/Kip or Ink4 classes of CDK inhibitors

27

what are 4 common cell cycle regulators that are commonly associated with cancer?

1. retinoblastoma protein (rb)
2. p21 or p16
3. mitogens
4. CDK's and cyclins

28

what is the function of retinoblastoma protein (Rb) and what is result of mutation?

cell cycle inhibitor, loss of Rb leads to tumors

29

what is the function of p21 or p16?

Cip.Kip and Ink4 CDK inhibitors respectively (loss of them results in cancer)

30

what is function of mitogens?

growth factor

31

what happens if there is an increase of mitogens?

increased cell proliferation possibly leading to cancer

32

what is function of CDK and cyclins?

cell cycle activators

33

what happens when there are increased levels of CDK and cyclins?

increased cell proliferation

34

what is the cell cycle checkpoint in G1?

monitors cell size and damage to cell

35

what is cell check point in G2?

checks for damage of new DNA

36

what is the cell checkpoint during mitosis?

spindle formation

37

what is the mechanism of a cell cycle checkpoint?

1. damage detected by sensor
2. transducers relay information to effectors through a signaling cascade
3. effectors arrest cell cycle until damage is remedied

38

where is information immediately relayed to when cell damage is found?

ATM and ATR

39

what type of cell damage is ATM specific to?

double strand breaks

40

what type of cell damage is ATR specific to?

non-specific

41

what is the pathway in cell cycle arrest involving BRCA2?

ATM and ATR relay information to BRCA2 which activates Chk1 or Chk2.

42

what does the BRCA2 pathway ultimately lead to?

cell cycle arrest, production of repair enzymes, or activation of p53

43

what molecule is p53 activated by in damaged cells?

Chk2

44

what is the pathway of cell cycle arrest that does not involve BRCA2?

direct activation of p53 which activates CDK inhibitor p21 leading to cell cycle arrest

45

what happens in S phase?

chromosome synthesis (replication) occurs

46

what occurs in M phase?

chromosome segregation

47

what happens in G1 and G2 phases?

gap phases before S and M phase. Cell regulation occurs in these phases. G1 contains restriction point (R)

48

how is retinoblastoma protein (Rb) deactivated?

phosphorylation by CDK phosphorylation