Biol 445 exam 2 Flashcards Preview

Spring 2013 > Biol 445 exam 2 > Flashcards

Flashcards in Biol 445 exam 2 Deck (49):
1

Cohesin

Holds sister chromatids together

2

MCM helicase

Melts DNA strands
Commitment step of DNA replication

3

Centrosomes

Organize microtubules that pull chromatids apart

4

Kinetochores

Where microtubules attach on the chromatids

5

Centromeres

The center of the kinetochores

6

Critical cell-cycle transitions

G1 -> S
G2 -> M

7

Scientist with budding yeast

Lee Hartwell

8

Scientist with fission yeast

Paul Nurse

9

Scientist with sea urchins

Tim Hunt

10

Budding yeast CDK

Cdc28

11

Fission yeast CDK

Cdc2

12

Human Cdc28/Cdc2 homolog

CDK1

13

Sea urchin discovery

Cyclins

14

MPF

Maturation promoting factor
Required to complete meiosis (signaled by progesterone)
Complex of CDK1 and cyclin B

15

Pathways of CDK regulation (3)

- Cyclin synthesis and destruction
- Phosphorylation of kinases
- CKIs

16

Ubiquitylation

Method of cyclin destruction
The creation of a chain of ubiquitins through isopeptide bonds

17

E3 ubiquitin ligase

Determines which kinases get ubiquitylated

18

Anaphase promoting complex (APC)

Mediates the destruction of mitotic cyclins
Destroys securin to activate separase, which cleaves cohesins
Activated by CDKs, regulated in a negative feedback loop

19

Elongated fission yeast mutants (Cdc25 and Wee1 levels)

Elevated Wee1
Decreased Cdc25

20

Small cell fission yeast mutants (Cdc25 and Wee1 levels)

Elevated Cdc25
Decreased Wee1

21

Cdc25

Phosphatase
Turns Cdc2 on after Wee1 turns it off

22

Wee1

Kinase
Turns Cdc2 off

23

Cell cycle transition controlled by Wee1 and Cdc25

G2 -> M

24

CKI families (2)
Cell cycle transition they regulate

p21
p16
G1 -> S transition

25

p21 binding target and action

CDKs + their cyclins
found in normal cells
arrest cells in response to DNA damage

26

p16 binding target and action

CDKs alone
found in cancer cells
involved in developmental control
a tumor suppressor gene

27

Requirements for proliferation

Growth and cell division

28

Cdc proliferation target

Cell division, not growth

29

Hayflick limit

Cells have a fixed number of divisions until they die
Correlated with telomere length
Cancer cells escape it

30

Growth factor point of action

G1 phase before R Point

31

Growth factor method of action

Induce gene expression

32

Cyclin D is activated by

Growth factors, among other things

33

Cyclin D function

Makes a complex with CDK4/CDK6
Brings the cell to S phase

34

General checkpoint pathway

DNA damage/replication stress -> Signals -> Sensors -> Transducers -> Effectors

35

ATM and ATR function

Sensors
Phosphorylate Cdc25, allowing 14-3-3 bind and escorting out of the cell

36

14-3-3

Bind to phosphorylated Cdc25, bringing it out of the cell

37

Spindle assembly checkpoint flow

Unattached kinetochores cause the formation of the MCC complex
MCC inhibits APC/C activation
APC/C is required to get rid of securin, and allow separase to break down cohesin

38

Tumor repressor phenotype: dominant or recessive

Recessive

39

Forms of retinablastoma

Sporadic
Familial

40

Knudson's 2-hit hypothesis

Familial retinablastomas required the acquisition of another mutation
Sporadic retinablastomas require the acquisition of 2 mutations

41

Retinablastoma recessive vs. dominant at cellular and inherited levels

Inherited as dominant
Recessive at the cellular level

42

Methods of losing heterozygosity

Mitotic nondisjunction/missegregation
Mitotic recombination

43

Mitotic nondisjunction/missegregation

Mitotic error causes the granddaughter to have 2 copies of the mutant allele

44

Mitotic reombination

During a crossing over event the mutant allele gets stuck on the wild type chromosome

45

pRb binding partner

E2F

46

pRb active vs inactive states

Inactive state: Hyperphosphorylated
Active state: Unphosphorylated or hypophosphorylated

47

pRb/E2F complex action

Transcriptional repressor
Recruits histone deacetylase

48

Action of E2F alone

Transcriptional activator
Recruits histone acetylase

49

pRb only binds to E2F when...

Hypophosphorylated or unphosphorylated