Cell Division

Question 1

5 Stages of Mitosis

Answer 1

IPMAT

Interphase, Prophase, (Prometaphase), Metaphase, Anaphase, Telophase

Question 2

Define: Centromere

Answer 2

chromatin that defined the site of microtubule attachment in mitosis. Confers mitotic stability

Question 3

Define: Kinetochore

Answer 3

multi proten complex that assembles on centromere, binds microtubules

Question 4

4 types of centromeric location

Answer 4

telocentric, acrocentric, submetacentric, metacentric

Question 5

What is the centromere paradox?

Answer 5

Centromere confers mitotic stability, but the sequence is not conserved across species. Specific nucleosomes actually define the centromere.

Question 6

CENP-A Function

Answer 6

H3 histone variant that is found at centromeres. Defines centromeres in higher eukaryotes

Question 7

Cryptic Centromeres

Answer 7

Centromeres found in chromosomes from chromosome fusion events in evolution

Question 8

Neocentromeres

Answer 8

Shows centromere sequence is not necessary for identity. Epigenetic acquisition of new centromere site when original site is deleted.

Question 9

CENP-B/C

Answer 9

Marks location of original centromere when neocentromeres are used

Question 10

α-Tubulin, β-tubulin Function

Answer 10

Tubulin monomers that form heterodimer

Question 11

GTP-Tubulin Function

Answer 11

Bind at end of GDP-Tubulin to cap microtubule

Question 12

MT Catastrophe Mechanism

Answer 12

GTP-tubulin cap is hydrolyzed to GDP-Tubulin

Protofilaments peel apart

Question 13

MT Rescue Mechanism

Answer 13

GTP-tubulin caps MT to prevent protofilament peeling

GTP-tubulin keeps getting added as soon as GTP-tubulin on cap gets dephosphorylated

Question 14

What is the PCM?

Answer 14

Pericentriolar matrix

Question 15

γ-Tubulin Function

Answer 15

Located in PCM, provides template for nucleation of MTs. lowers energy barrier for MT formation

Question 16

Centrosome Function

Answer 16

Microtubule organizing center in animal cells

Question 17

Centrosome Components

Answer 17

Centrioles, Microtubules, PCM.

Question 18

How do supernumary centrosomes form?

Answer 18

When centrioles divide more than once, more than one centrosome can be created.

Question 19

What allows chromosome movement during the cell cycle?

Answer 19

Depolymerization of microtubules attached to kinetochores

Question 20

Function: Cohesin

Answer 20

Tripartite ring that holds sister chromatids together by topologically embracing molecules

Question 21

Structure: Cohesin

Answer 21

Smc1, Smc3, Scc1 (cleavage site)

Question 22

T/F. Sister chromatid disjunction is a seperable event from mitotic exit.

Answer 22

True

Question 23

Function: APC/C

Answer 23

Coordinates anaphase with mitotic exit by ubiquitinating Cyclin B1 and Securin

Question 24

Function: Cyclin B1

Answer 24

Needs to be degraded for mitotic exit

Question 25

Function: Securin

Answer 25

Binds to Separase and will not release until it is degraded upon ubiquitination by APC/C

Question 26

Function: Separase

Answer 26

cleaves Cohesin at Scc1 site (Kleisen) to allow sister chromatid disjunction

Question 27

Mechanism: Sister Chromatid Disjunction

Answer 27

1) APC/C^Cdc20 gets activated, ubiquitinates Securin and Cyclin B1 2) Degraded Securin allows Separase to cleave Cohesin at Kleisin (Scc1) 3) Sister chromatid can separate 4) Cells exit mitosis after degradation of Cyclin B1

Question 28

Function: MAD1

Answer 28

Release inhibitory signal that will activate MCC when MTs are not attached to kinetochore

Question 29

Function: MCC

Answer 29

Inhibit APC/C

Question 30

Mitotic/Spindle Assembly Checkpoint

Answer 30

1) Unattached kinetochore still has MAD1 2) MAD1 release signal, activates MCC, which inhibits APC/C 3) One all microtubules attach, MAD1 is released from kinetochore 4) MCC is no longer functional once MAD1 is released from ALL kinetochore 5) APC/C can ubiquitinate Securin and Cyclin B1

Question 31

4 Types of Erroneous MT Interactions

Answer 31

Amphitelic (normal), Monotelic (release diffuse inhibitory signal), syntelic, merotelic

Question 32

Function: Aurora B

Answer 32

kinase at centromere that senses tension. Low tension applies, phosphorylates components of outer kinetochore Tension: Does not phosphorylate

Question 33

What type of division occurs in Meiosis I?

Answer 33

Reductional Division

Question 34

What type of division occurs in Meiosis II?

Answer 34

Equational Division

Question 35

How is cohesion lost in two distinct steps in Meiosis?

Answer 35

In meiosis 1, separase cleaves cohesins found in arms, but Sgo1 is still present at centromeres In meiosis 2, separase cleaves cohesins (Sgo1) present at centromeres.

Question 36

What chromosomal state to tumors have?

Answer 36

Aneuploid, due to supernumary centrosomes that facilitate merotelic attachment