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MBG Flashcards > Cell Division > Flashcards

Cell Division Flashcards

Andrew Holland Lecture 2

1
Q

5 Stages of Mitosis

A

IPMAT

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

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2
Q

Define: Centromere

A

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

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3
Q

Define: Kinetochore

A

multi proten complex that assembles on centromere, binds microtubules

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4
Q

4 types of centromeric location

A

telocentric, acrocentric, submetacentric, metacentric

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5
Q

What is the centromere paradox?

A

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

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6
Q

CENP-A Function

A

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

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7
Q

Cryptic Centromeres

A

Centromeres found in chromosomes from chromosome fusion events in evolution

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8
Q

Neocentromeres

A

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

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9
Q

CENP-B/C

A

Marks location of original centromere when neocentromeres are used

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10
Q

α-Tubulin, β-tubulin Function

A

Tubulin monomers that form heterodimer

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11
Q

GTP-Tubulin Function

A

Bind at end of GDP-Tubulin to cap microtubule

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12
Q

MT Catastrophe Mechanism

A

GTP-tubulin cap is hydrolyzed to GDP-Tubulin

Protofilaments peel apart

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13
Q

MT Rescue Mechanism

A

GTP-tubulin caps MT to prevent protofilament peeling

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

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14
Q

What is the PCM?

A

Pericentriolar matrix

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15
Q

γ-Tubulin Function

A

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

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16
Q

Centrosome Function

A

Microtubule organizing center in animal cells

17
Q

Centrosome Components

A

Centrioles, Microtubules, PCM.

18
Q

How do supernumary centrosomes form?

A

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

19
Q

What allows chromosome movement during the cell cycle?

A

Depolymerization of microtubules attached to kinetochores

20
Q

Function: Cohesin

A

Tripartite ring that holds sister chromatids together by topologically embracing molecules

21
Q

Structure: Cohesin

A

Smc1, Smc3, Scc1 (cleavage site)

22
Q

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

A

True

23
Q

Function: APC/C

A

Coordinates anaphase with mitotic exit by ubiquitinating Cyclin B1 and Securin

24
Q

Function: Cyclin B1

A

Needs to be degraded for mitotic exit

25
Q

Function: Securin

A

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

26
Q

Function: Separase

A

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

27
Q

Mechanism: Sister Chromatid Disjunction

A

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

28
Q

Function: MAD1

A

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

29
Q

Function: MCC

A

Inhibit APC/C

30
Q

Mitotic/Spindle Assembly Checkpoint

A

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

31
Q

4 Types of Erroneous MT Interactions

A

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

32
Q

Function: Aurora B

A

kinase at centromere that senses tension.

Low tension applies, phosphorylates components of outer kinetochore
Tension: Does not phosphorylate

33
Q

What type of division occurs in Meiosis I?

A

Reductional Division

34
Q

What type of division occurs in Meiosis II?

A

Equational Division

35
Q

How is cohesion lost in two distinct steps in Meiosis?

A

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.

36
Q

What chromosomal state to tumors have?

A

Aneuploid, due to supernumary centrosomes that facilitate merotelic attachment

MBG Flashcards (12 decks)

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