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C Bio > Cellular Reproduction: Mitosis & Cytokinesis (4) > Flashcards

Cellular Reproduction: Mitosis & Cytokinesis (4) Flashcards

1
Q

prophase

A

nuclear envelop disappears & c’somes condense (lamins)

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2
Q

prometaphase

A

mitotic spindle forms: c’somes attach to spindle

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3
Q

metaphase

A

c’somes aligned along equator

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4
Q

anaphase

A

chromatids separate; c’somes migrate to poles

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5
Q

telophase

A

c’somes decondense; nuclear envelope forrms

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6
Q

mitosis

A

process of partitioning newly replicated chromosomes into separate parts of the cell

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7
Q

astral microtubules

A

radiate from centrosome, form aster (centrosome is essentially a microtubule organizing center)

Help mitotic apparatus, determine cleavage

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8
Q

kinetochore microtubules

A

attach to chromosomes at kinetochore; pull chromosomes to diff poles

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9
Q

polar microtubules

A

connect to opposing pair, support framework & help push centrosomes apart

Help push centrosomes apart

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10
Q

minus end. Lose or gain microtubules?

A

point toward centrosome & away from kinetochore

lose microtubules

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11
Q

plus end. Lose or gain microtubules?

A

point away from centrosome

gain

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12
Q

how do the + & - ends differ?

A

differ in rates of assembly

higher at + & low at -

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13
Q

what are the 2 events in spindle assembly?

A

Formation of Poles: spindle microtubules must “attach” or anchor to poles
Get longer & attach to microtubules
Capture of chromosomes: spindle microtubules must attach to chromosomes

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14
Q

when are centrosomes made?

A

S phase

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15
Q

how do centrosomes move to poles?

A

motor PROs

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16
Q

microtubule organizing center

A

duplication of centrosomes

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17
Q

what do motor PROs ensure in prophase?

A

microtubules are properly aligned

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18
Q

kinesins

A

walk toward + end of MT

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19
Q

dyneins

A
  • end directed motor PROs, move towards _ end
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20
Q

how do motor PROs help align microtubules? & when does this occur?

A

identify plane of cell division & align accordingly

form an array during the beginning of mitosis

prophase

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21
Q

what determines the plane of cell division?

A

distance b/w 2 centrosomes

22
Q

What are the 3 movements of centrosomes during late Prophase?

A

motor PROs help align microtubules

centrosome alignment

centrosome separation

23
Q

what causes microtubules to shorten?

A

Dynein PRO is anchored into the membrane, when it moves towards the minus end it causes the astral microtubules to shorten & pulls

24
Q

what pushes microtubules?

25
what pulls microtubules?
dyneins
26
Centromeric heterochromatin
highly condensed DNA non-coding, provides structure to c'some to hold in correct shape has binding factors mediating MT
27
fibrous corona
outermost layer of the kinetochore
28
where is the region of growth in microtubules? & how is it done? & where?
plus end tubulin subunits added to continue growth kinetochore
29
where do the microtubules attach?
outermost layer --> fibrous corona
30
what mediates MT in lengthening?
centromeric heterochromatin has binding factors mediating MT
31
when does c'some capture occur?
prometaphase once the nuckear envelope is broken down
32
when are there rapid fluctuations in MT lenghth?
prometaphase during c'some capture
33
what generates c'some movement
MT dynamics & motors rapid depolymerization & polymerization occurring at the + end (at kinetochore)
34
MT motors assist in:
maintaining flow of tubulin tethering the kinetochore
35
treadmilling
no net elongation/shrinking of the MT
36
how was tubulin movement determined?
red labeled tubulin subunits were added to a cell red dye is seen only at the kinetochores at first --> site of addition red labeled subunits began to be pushed to the minus end
37
depolymerization in MTs
met loss at the + end & c'some moves to the right
38
polymerization
net gain at the + end & c'some moves away from centrosome
39
how is there enough room for tubulin subunits to be added?
MT PROs hold the MT far enough away from the kinetochore
40
spindle checkpoint
cell monitors status of events before going on to anaphase, important for the c'somes to be evenly lined up if one of the c'somes isn't at the metaphase plate it waits to give it a chance to get there
41
Mechanism of the Spindle Checkpoint
Securin holds sister chromatids APC causes ubiquitination of securin enabling chromatids to split apart Cdc20 activates APC (positive regulator) MAD2PRO attaches to the kinetochore of improperly aligned c’somes inhibiting cdc20 prevents chromosomes from separating
42
What causes the inhibition of cdc20?
MAD2PRO
43
what PROprevents improper separation of c'somes?
MAD2PRO
44
cleavage furrow
method of cytokinesis in animals constriction occurs with a contractile ring contractile PRO (actin & myosin II) slide past each other shortening their lengths
45
Actin
• cytoskeleton PRO of the cleavage furrow | Pulled by myosin II causing it to shorten
46
Myosin II
head PRO of the cleavage furrow | Pulls actin filaments causing the actin to become smaller
47
What is the evidence for myosin II in cytokinesis? & what were the results?
Myosin II Knock-outs gene for myosin II is deleted Antisense inhibition of myosin II mRNA Antimyosin II antibodies Bind to myosin & disrupts structure (function) resulting in an abnormal cell results: cell that can replicate their c'somes but are unable to divide --> results in large, multinucleated cells
48
Why is binding an antibody useful in PRO inhibition?
high specificity binding an antibody to a PRO may disrupt the normal function of the PRO due to steric hindrance
49
what is an ex of mitosis without cell division? & how can we study nuclei?
early insect embryos --> syncytial blastoderm nuclear divisions occur without cell division creating a big, nucleated cell to enhance PRO production. Once there is enough PRO, membranes will form around the nuclei GFP labeling of c'somes
50
what is the benefit of multinucleated cells?
rapid gene expression --> lots of PRO & RNA
51
what is an ex of cell division wtihout DNA rep?
meiosis 2 sequential cell divisions without an intervening phase of replication

C Bio (30 decks)

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