Biol 445 exam 2

Question 1

Cohesin

Answer 1

Holds sister chromatids together

Question 2

MCM helicase

Answer 2

Melts DNA strands

Commitment step of DNA replication

Question 3

Centrosomes

Answer 3

Organize microtubules that pull chromatids apart

Question 4

Kinetochores

Answer 4

Where microtubules attach on the chromatids

Question 5

Centromeres

Answer 5

The center of the kinetochores

Question 6

Critical cell-cycle transitions

Answer 6

G1 -> S

G2 -> M

Question 7

Scientist with budding yeast

Answer 7

Lee Hartwell

Question 8

Scientist with fission yeast

Answer 8

Paul Nurse

Question 9

Scientist with sea urchins

Answer 9

Tim Hunt

Question 10

Budding yeast CDK

Answer 10

Cdc28

Question 11

Fission yeast CDK

Answer 11

Cdc2

Question 12

Human Cdc28/Cdc2 homolog

Answer 12

CDK1

Question 13

Sea urchin discovery

Answer 13

Cyclins

Question 14

MPF

Answer 14

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

Question 15

Pathways of CDK regulation (3)

Answer 15

• Cyclin synthesis and destruction
• Phosphorylation of kinases
• CKIs

Question 16

Ubiquitylation

Answer 16

Method of cyclin destruction

The creation of a chain of ubiquitins through isopeptide bonds

Question 17

E3 ubiquitin ligase

Answer 17

Determines which kinases get ubiquitylated

Question 18

Anaphase promoting complex (APC)

Answer 18

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

Question 19

Elongated fission yeast mutants (Cdc25 and Wee1 levels)

Answer 19

Elevated Wee1

Decreased Cdc25

Question 20

Small cell fission yeast mutants (Cdc25 and Wee1 levels)

Answer 20

Elevated Cdc25

Decreased Wee1

Question 21

Cdc25

Answer 21

Phosphatase

Turns Cdc2 on after Wee1 turns it off

Question 22

Wee1

Answer 22

Kinase

Turns Cdc2 off

Question 23

Cell cycle transition controlled by Wee1 and Cdc25

Answer 23

G2 -> M

Question 24

CKI families (2)
Cell cycle transition they regulate

Answer 24

p21
p16
G1 -> S transition

Question 25

p21 binding target and action

Answer 25

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

Question 26

p16 binding target and action

Answer 26

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

Question 27

Requirements for proliferation

Answer 27

Growth and cell division

Question 28

Cdc proliferation target

Answer 28

Cell division, not growth

Question 29

Hayflick limit

Answer 29

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

Question 30

Growth factor point of action

Answer 30

G1 phase before R Point

Question 31

Growth factor method of action

Answer 31

Induce gene expression

Question 32

Cyclin D is activated by

Answer 32

Growth factors, among other things

Question 33

Cyclin D function

Answer 33

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

Question 34

General checkpoint pathway

Answer 34

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

Question 35

ATM and ATR function

Answer 35

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

Question 36

14-3-3

Answer 36

Bind to phosphorylated Cdc25, bringing it out of the cell

Question 37

Spindle assembly checkpoint flow

Answer 37

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

Question 38

Tumor repressor phenotype: dominant or recessive

Answer 38

Recessive

Question 39

Forms of retinablastoma

Answer 39

Sporadic | Familial

Question 40

Knudson's 2-hit hypothesis

Answer 40

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

Question 41

Retinablastoma recessive vs. dominant at cellular and inherited levels

Answer 41

Inherited as dominant | Recessive at the cellular level

Question 42

Methods of losing heterozygosity

Answer 42

Mitotic nondisjunction/missegregation | Mitotic recombination

Question 43

Mitotic nondisjunction/missegregation

Answer 43

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

Question 44

Mitotic reombination

Answer 44

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

Question 45

pRb binding partner

Answer 45

E2F

Question 46

pRb active vs inactive states

Answer 46

Inactive state: Hyperphosphorylated | Active state: Unphosphorylated or hypophosphorylated

Question 47

pRb/E2F complex action

Answer 47

Transcriptional repressor | Recruits histone deacetylase

Question 48

Action of E2F alone

Answer 48

Transcriptional activator | Recruits histone acetylase

Question 49

pRb only binds to E2F when...

Answer 49

Hypophosphorylated or unphosphorylated