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Cell Biology > Chapter 17 > Flashcards

Chapter 17 Flashcards

1
Q

What are the different phases in the cell cycle

A 
Interphase :
       G1 phase 
        S phase
        G2 phase
M phase 
       Mitosis
        Cytokinesis
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2
Q

What happens in the prophase ?

A

Condensation of chromosomes;

Centrosomes have duplicated and the mitotic spindles form

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3
Q

What are condensins

A

5- subunit protein complex that reassembles cohesion

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4
Q

What happens in prometaphase

A

Nuclear envelop breaks down; spindles connect to chromosomes by their kinetochores and begin movement

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5
Q

What triggers the formation of the mitotic spindle

A

M-Cdk

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6
Q

What happens in meta phase

A

Chromosomes align at equator of each spindle pole by way of the microtubules of the mitotic spindle

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7
Q

What happens in anaphase

A

The sister chromatids separate to form daughter chromosomes that are pulled apart towards the spindle pole microtubules shorten and pokes move more apart

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8
Q

What happens in telophase

A

The daughter chromosomes decondense ; nuclear envelope reassembles ; contractile ring begins to contract

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9
Q

What happens in cytokinesis

A

Nuclear envelop surrounds chromosomes

Contractile ring has created cleavage furrow and cytoplasm is divided in two

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10
Q

This acts as a microtubule organizing center

A

Centrosomes

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11
Q

When does the duplication of the centrosomes begin and complete

A

S-phase

G2

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12
Q

Which protein help keeps the poles apart

A

Kinesin-5

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13
Q

Which proteins pulls poles toward each other

A

Kinesin-14

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14
Q

These proteins pushed chromosomes away from poles

A

Kinesin-4

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15
Q

These proteins keep spindle poles away from each other and near cortex

A

Dyneins

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16
Q

What is the arrangement of the sister kinetochores

A

Back - back

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17
Q

What protein helps remove cohesions in anaphase

A

Separase

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18
Q

What activated separase

A

Anaphase promoting complex

APC/C

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19
Q

What is an active anaphase promoting complex reffered as

A

Ubiquitin ligase

Degraded proteins like M-Cdk

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20
Q

What keeps separase inactive

A

Securin

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21
Q

How does the separase become active to remove cohesions

A

When APC/C becomes active it adds ubiquitin to securin which targets it for degradation which will allow separase to become active and will then degrade the cohesion of the sister chromatids

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22
Q

What happens in anaphase A

A

Sister chromatids separate

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23
Q

What happens in anaphase B

A

Spindle pokes move away from each other

24
Q

What is the contractile ring made of

A

Actin and myosin Filaments

25
What allows the formation of parallel actin bundles in the contractile ring
Formin
26
What needs to be activated in order for the contractile ring to assemble and contract
RhoA
27
Name the phases of the cell cycle
G1 S phase G2 phase M phase
28
What gives the cell cycle its quality control feature
Various checkpoints G1/S - G2/M Metaphase ti anaphase
29
What mediates the transition from one phase to another in the cell cycle
By cyclins and | Cyclin dependent kinases ( Cdk)
30
When is Cdk active
When bound to cyclin
31
Will progression of phases continue if Cdk is active
No
32
The expression of this changes with the stages of the cell cycle
Cyclin
33
How is the Cdk activated by cyclins
When cyclin is not present Cdks active site is blocked by a loop When cyclin is bound to Cdk the loop is removed and activated Cdk
34
When Cdk is active in the G1/S - G2/M phase what does it do to various proteins
Phosphorylates them so that the cell cycle progresses
35
In comparison with the progression of the G1/S -G2/M stage what is the different in the metaphase to anaphase progression
Metaphase to ananphase progression requires degradation not phosphorylation
36
What promotes the replication of DNA only once during the cell cycle
S-Cdk
37
How are the sister chromatids held together after the DNA has been replicated
Cohesions
38
What is the name of the stage in the cell cycle where cell divides in 2 daughter cells
Mitosis
39
What mediates crossing over
Synaptomenal complex
40
What happens in meiosis I
Homologous chromosomes pair together | Non sister chromatids exchange genetic material ( crossing over )
41
What is one difference from meiosis I and meiosis II
In meiosis I it is the separation of the homologous chromosomes In meiosis II it’s separation of sister chromatids
42
Nondisjunctuon
Phenomenon that when homologs fail to separate properly | Some haploid gametes have more copies of chromosomes while others lack chromosome
43
What are extracellular factors that influence cell growth and division
Mitogens Growth factors Survival factors
44
What do mitogens do
Promote cell division They activate Ras and MAP kinase pathway Triggers G1- Cdk and S -Cdk to activate
45
In what phase does chromosome duplication occur
S Phase | (DNA ) synthesis
46
In what phase of the cell cycle does chromosome segregation and cell division occur
M-Phase
47
What is the mitotic spindle
Giant bipolar array of microtubules
48
G1, S, G2 are together called
Interphase
49
Which phase requires the most time
Interphase
50
Why are the gap phases G1 and G2 important
Provides time for the cell to monitor the internal and external environment to ensure conditions are suitable to proceed to S phase and mitosis
51
What what are two components of the cell cycle control system
Cyclin | Cyclin dependent protein kinase ( Cdk)
52
What helps the cyclin Cdk complex become fully activated
CAK Cdk- activating kinase It phosphorylates an amino acid near the entrance of the Cdk active site
53
What is the key regulator of the metaphase to anaphase transition
APC/ C (Anaphase promoting complex Cyclosome)
54
What are the two proteins that APC/C target for destruction
Securins - hold sister chromatids together | S- and M- cyclin s - inactivated most Cdks in the cell
55
How does cyclin activate Cdk
It binds causing a loop to move away from the active site
56
What type of enzyme is APC/C
Ubiquitin ligase
57
What inactivates cyclin Cdk complexes in
CkIs ( Cdk inhibitor proteins

Cell Biology (10 decks)

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