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Biology > Exam 4 Ch 19 > Flashcards

Exam 4 Ch 19 Flashcards

(43 cards)

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1
Q

What controls the cell cycle?

A

Cyclin-dependent kinases (CDKs)

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2
Q

What is the accessory protein that binds to CDKs and control their activity?

A

cyclins

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3
Q

How are CDKs activated?

A

Activated when bound to a cyclin

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4
Q

What are the cell levels for CDKs like?

A

They do not change

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5
Q

What kind of cyclins do G1 cyclins have?

A

Cyclin D

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6
Q

G1 cyclin is linked to signals by what?

A

growth factors

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7
Q

G1 cyclins induce production of what?

A

Cyclin D, G1/S cyclins and proteins for DNA replication

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8
Q

What kind of cyclin do G1/S cyclins have?

A

Cyclin E

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9
Q

What cyclin gets the cell past the restriction point?

A

G1/S cyclins

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10
Q

What is the s phase?

A

DNA synthesis phase, Replication machinery assembled, centrosome is duplicated

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11
Q

What happens to the centrosome during S phase?

A

Centrosome is duplicated and becomes the spindle poles

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12
Q

What are the S phase cyclins?

A

Cyclin A and cyclin E

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13
Q

What are the S phase cyclins responsible for?

A

Inducing DNA synthesis: activate enzymes for DNA synthesis and loading polymerases on the DNA

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14
Q

DNA of homologous chromosomes is replicated in what phase?

A

S phase

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15
Q

During the S phase, there are an _n set of chromosomes

A

4

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16
Q

What are chromatids?

A

Identical chromosomes of replicated chromosomes

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17
Q

What are sister chromatids?

A

The two identical chromatids

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18
Q

Sister chromatids are held together by the ______ and ______

Study These Flashcards
A

Centromere and cohesions

19
Q

During G1 phase, how are cohesions?

Study These Flashcards
A

Cohesins associate with the chromosomes

20
Q

During S phase, how are cohesions?

Study These Flashcards
A

As DNA is replicated, replication fork passes through the cohesion loops
After replication passes, cohesins “glue” the sister chromatids together

21
Q

During the G2 phase, cell must verify:

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A

All the DNA has been correctly duplicated
DNA is sufficient to produce two cells
Errors made during DNA replication are repaired
Any breaks in the DNA are repaired

22
Q

The cell has to verify all the DNA has been correctly duplicated, DNA is sufficient to produce two cells. Errors made during DNA replication are repaired and any breaks in the DNA are repaired because

2 reasons. What are causing the errors?

Study These Flashcards
A

Cell stress and damage due to radiation, chemicals or drugs that interfere with microtubules

23
Q

At G2-M checkpoint what are the major detectors of DNA damage?

Study These Flashcards
A

ATM (ataxia telangiectasia mutated)
ATR (ataxia telangiectasia Rad3- related protein)
DNA-PK(DNA-dependent protein kinase)

24
Q

What do the major detectors of DNA damage do?

Study These Flashcards
A

These all detect lesions in DNA
Recruit DNA repair mechanisms
If a DNA cannot be repaired– apoptosis (cell death)

25
What are the mitotic cyclins that induce mitosis?
Cyclin A and Cyclin B
26
Mitotic cylin causes entry into mitosis, what happens?
Chromosome condensation Nuclear envelope breakdown Mitotic spindle formation Etc.
27
When does Cyclin B start producing?
Starts at S phase. Present BUT no enzyme activity until G2 phase
28
Cyclin B/CDK1 is present but is NOT active because _____ _____ phosphorylates CDK1 to keep it inactivated
Wee1 kinase
29
Once DNA replication is finished, how is mitosis induced?
Cdc25 phosphatase removes inhibitory phosphates from CDK1
30
How do you rapidly remove cyclin to inactivate the CDKs to induce mitosis?
By rapid destruction of the cyclins using the proteasome APC/C is an E-3 ligase Binds to cyclins and ubiquitinates them But not the CDKs This target the cyclin for destruction by the proteasome CDK becomes inactive without the cyclin
31
6 stages of mitosis
Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis
32
Interphase
Chromosomes duplicated during S-phase Centrosome duplicated
33
Prophase
Chromosomes condense( Chromatids attached at the centromere) Cohesion proteins broken down so sister chromatids connected only by the centromere (Some cohesion remind at the centromere which holds the sister chromatids together) Nucleoli disappear Duplicated centrosomes– now spindle poles move to opposite poles of the cell Spindle fibers begin to form Kinetochore assembles at the centromere of each chromosome
34
The kinetochore
structure forms at the centromere of the chromosomes Kinetochore creation happens during prophase The spindle fiber microtubules then attach to the kinetochore during the next phase prometaphase
35
Prometaphase
Chromosomes continue to condense Mitotic spindle microtubules attach to the kinetochores Nuclear envelope breaks down
36
How do the spindle fiber microtubules attach to the kinetochore?
Use "search and capture" mechanism
37
Spindle fiber microtubules use “search and capture” mechanism to attach to the kinetochore. What happens if there are inccorect attachments?
Forms unstable interactions
38
What is the dissolution of the nuclear envelope during interphase and in prophase
In interphase, the chromosomes are tethered to the ring of nuclear lamins just under the nuclear envelope In prophase, nuclear lamins dissolve into the cytosol and trigger the nuclear membrane to fragment
39
Metaphase
Chromosomes line up at the metaphase plate Each sister chromatid is attached to a spindle fiber via the kinetochores Spindle fibers radiate out from the spindle poles at opposite sides of the cell Chromosomes move to be equidistant between the two spindle poles
40
How does movement of chromosomes occur
Involves kinesin and dynein motor protein walking on the microtubules to position the chromosomes Along with microtubule assembly and disassembly
41
Anaphase
Remaining cohesins at the centromere are destroyed Sister chromatids are pulled apart toward opposite poles by: Microtubule depolymerization at the kinetochore and motor proteins pulling the spindle fibers at the kinetochore and the spindle pole
42
Telophase
Chromosomes reach the opposite poles Chromosomes decondense Nuclear envelope reforms around the chromosomes Mitotic spindle breaks down Contractile ring forms under the membrane
43
Cytokinesis
Contractile ring from telophase contracts due to actin and myosin Contraction of the ring forms a cleavage furrow Pinches the cell into two

Biology (5 decks)

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