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EOM Test 3 > Mitosis > Flashcards

Mitosis Flashcards

1
Q

What are the stages of mitosis?

A

Prophase

Metaphase

Anaphase

Telophase

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2
Q

How is Mitosis regulated?

A

MPF phosphorylates Aurora kinase, which phosphorylates Polo-like kinase

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3
Q

What four things happen as a result of MPF activation?

A

Chromatin condensation

Nuclear envelope breakdown

Fragementation of the Golgi

Spindle formation

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4
Q

What are the features of prophase?

A

Chromosome condensation

Nuclear envelop breakdown

Spindle formation begins

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5
Q

What is cohesin?

A

multi-subunit complex that maintains linkage of newly synthesized sister chromatids

adhere along full length of the chromosome during S phase

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6
Q

What is Condensin?

A

Promotes condensation in a process that requires ATP

Target of MPF and Aurora B

Contains proteins related to cohesion

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7
Q

What happens to cohesin during prophase?

A

Removed from most of the lingth of the chromosome arms, but remains at the centromere

At the same time condensin begins to condens the chromosome

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8
Q

How does the nuclear envelope breakdown and what does it allow?

A

Lamins depolymerize when they are phosphorylated by MPF

Membrane proteins and Lamin B diffuse to ER, Lamin A and C disperse to the cytoplasm

Allows chromosome segregation by giving the spindle access to chromosomes

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9
Q

What occurs during prometaphase?

A

Spindle formation and the attachment of chromsomes to the kinetochore

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10
Q

What are the four types of Microtubules?

A

Kinetochore - attaches to kinetochores

Chromosomal - attaches to chromosome ends

Polar (Inter) - Separates poles

Astral - position and orient spindle

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11
Q

What are Microtubule associated proteins (MAPs)?

A

Regulate assembly and disassembly of microtubules

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12
Q

What are Dynein and Kinesin?

A

Motor proteins associated with microtubules

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13
Q

What are centromeres?

A

Repetitive DNA sequences where the spindle fibers connect.

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14
Q

What is the Kinetochore?

A

Protein complex that binds centromere and spindle microtubules

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15
Q

What is Histone H3-like centromeric protein (CENP)?

A

Bind DNA and kinetochore proteins for attachment of mitotic spindle

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16
Q

What is CENP-E?

A

A Tension sensor protein that transmits information about microtubule attachment to regulatory complex

17
Q

What is the Mitotic Checkpoint Complex?

A

Formed at unattached kinetochore and inhibits APC

Cdc20 is a part of this complex

18
Q

What is Cdc20?

A

A required activator of APC

Activity blocked when part of MCC

19
Q

What occurs when all chromosomes are properly oriented?

A

The MMC dissociates and APC is no longer inhibited, allowing it to trigger transition into anaphase by causing Cyclin B degredation

20
Q

What is Anaphase A?

A

Sister chromatid separation in anaphase

21
Q

What is Anaphase B?

A

The separation of the spindle poles during anaphase

22
Q

What does the degredation of cyclin B cause?

A

The beginning of the exit to mitosis

23
Q

What Anaphase Promoting Complex (APC)?

A

Ubiquitin ligase (E3) that targets Securin and Cyclin B for degredation

24
Q

What is Securin?

A

Protein bound to separase that inhibits its function

When it is ubiquitinated by APC, it releases separase to promote chromosome separation

25
Q

How do chromsomes physically segregate?

A

Via movement along kinetochore microtubules mediated by dynein

26
Q

What is nondisjunction?

A

Failure to complete chromosome segregation

Results in aneuploidy

27
Q

How do spindle poles separate?

A

Polar microtubules slide past each other via plus end directed motor proteins (Push)

Astral microtubules move spindle pole toward cell periphery via minus end motor proteins (Pull)

28
Q

What causes the beginning of telophase and cytokinesis?

A

Cyclin B degradation via APC causes a decrease in MPF activity

29
Q

What are the features of telophase?

A

Nuclear envelope reassembled

Chromosomes decondense –> b/c entering G1

Formation of cleavage furrow

30
Q

How does the nuclear membrane reassemble?

A

Decreased kinase activity and dephosphorylation by Cdc14 phosphatase promote reassembly

B lamins and inner membrane proteins bind chromatin and pull membrane around chromosomes

Lamins A and C are imported via reformed NPCs

31
Q

What is the Contractile Ring?

A

Actin filaments attached to the plasma membrane

Bipolar myosin II interacts with the AFs in sliding mechanism to contract the ring along the cleavage furrow

32
Q

How is Cytokinesis regulated?

A

Before Anaphase - by high MPF activity, active myosin light chain phosphatase, prevents mysoin II activation

At Anaphase - MPF activity decreases - allows activation of myosin II

During Cytokinesis - Transient increase in Ca activates MLC kinase

EOM Test 3 (19 decks)

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