first step of M phase or mitosis - Replicated chromosomes condense - mitotic spindle assemble between the two centromeres

Cell Cycle Week 5 Holy Flashcards by Weston Tardy

Prophase-

first step of M phase or mitosis

Replicated chromosomes condense
mitotic spindle assemble between the two centromeres

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first step of M phase or mitosis

Replicated chromosomes condense
mitotic spindle assemble between the two centromeres

Prophase

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Prometaphase-

second step of mitosis

- nuclear envelope dissociates
- chromosomes attach to spindle microtubules via kinetochores

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second step of mitosis

- nuclear envelope dissociates
- chromosomes attach to spindle microtubules via kinetochores

Prometaphase

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Metaphase-

third step of mitosis

-chromosomes aligned at the equator of the cell

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third step of mitosis

-chromosomes aligned at the equator of the cell

Metaphase

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Anaphase-

fourth step of mitosis

- sister chromatids separate 
- kinetochore microtubules get shorter

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fourth step of mitosis

- sister chromatids separate 
- kinetochore microtubules get shorter

Anaphase

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Telophase-

fifth step of mitosis

- daughter chromosomes arrive at poles and decondense
- new nuclear envelope begins to form
- contractile ring forms around center of cell in preparation for cytokinesis

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fifth step of mitosis

- daughter chromosomes arrive at poles and decondense
- new nuclear envelope begins to form
- contractile ring forms around center of cell in preparation for cytokinesis

Telophase

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Cytokenesis-

contractile ring made of actin and myosin filaments pinches the cell in two creating two daughter cells

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contractile ring made of actin and myosin filaments pinches the cell in two creating two daughter cells

Cytokenesis

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Rho proteins-

small G proteins that stimulate actin polymerization; important in formation of contractile ring during telophase and cytokinesis

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small G proteins that stimulate actin polymerization; important in formation of contractile ring during telophase and cytokinesis

Rho proteins

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Cohesins-

multi protein complexes that help keep replicated chromosome pairs (daughter chromatids) together until it is time to separate them during, help prevent premature separation and aneuploidy

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multi protein complexes that help keep replicated chromosome pairs (daughter chromatids) together until it is time to separate them during, help prevent premature separation and aneuploidy

Cohesins

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Condensins-

multi protein complexes related to cohesins but are involved in the tight packaging of chromatin in mitosis

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multi protein complexes related to cohesins but are involved in the tight packaging of chromatin in mitosis

Condensins

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Kinetochore-

complex of protein that assembles on centromeric DNA, made up of centromeric heterochromatin, histone H3 variant called CENP-A. Identifies the location for kinetochore formation.

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complex of protein that assembles on centromeric DNA, made up of centromeric heterochromatin, histone H3 variant called CENP-A. Identifies the location for kinetochore formation.

Kinetochore

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CENP-A-

histone H3 variant located on the centromeric heterochromatin; identifies location for assembly of kinetochores

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histone H3 variant located on the centromeric heterochromatin; identifies location for assembly of kinetochores

CENP-A

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Kinetochores-

interact with microtubule of the spindle apparatus for separation of daughter chromatids; have signaling function as metaphase checkpoints

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interact with microtubule of the spindle apparatus for separation of daughter chromatids; have signaling function as metaphase checkpoints

Kinetochores

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Kinetochore microtubules-

pull daughter chromosomes apart at kinetochores

Kinetochore microtubules

Interpolar microtubules-

push chromosomes away from poles to align during formation of metaphase plate; also push against eachother to elongate the spindle in late anaphasae

Interpolar microtubules

Astral microtubules-

push chromosomes away from poles during formation of metaphase plate

Astral microtublues

Contractile ring-

formed by contractile fibers of actin and myosin which are controlled by Rho; pinches of two cells during cytokinesis

Contractile ring

CDK-

cyclin dependent kinase, the catalytic subunit of the cell cycle

CDK

Cyclin-

the regulatory subunit of the cell cycle

Cyclin

CKIs-

cyclin dependent kinase inhibitors; two families, CIP/KIP (p21,p27), and Ink4a (p15, p16

CKIs

CIP/KIP (p21, p27)-

CKIs that bind cyclin-CDK complexes; upregulated by p53 in response to DNA damage

CIP/KIP (p21, p27)

Ink4a (p15, p16)-

bind to CDK subunits and prevent cyclin association, upregulated by environmental signaling

Ink4a (p15, p16)

Cyclin D, CDK 4 or 6 (which phase?)-

associated with G1

Cyclin B, CDK 1 (which phase?)-

associated with M phase

CAK-

phosphorylates active site of CDK

CAK

Wee1 kinase-

phosphorylates deactivation site of CDK; inhibited by active M-Cdk→positive feedback for continuation of M phase

Wee1 kinase

Cdc-25-

removes phosphate added to CDK by Wee1, activates M-Cdk which activates more Cdc-25 through positive feedback

Cdc-25

Mitogen growth factor-

activates Ras G protein on plasma membrane to move cell from G0 to G1

Mitogen growth factor

Ras-

activated by mitogen growth factor, Ras activates MAP kinase cascade

activated by mitogen growth factor, activates MAP kinase cascade:

Ras

MAP kinase-

Activated by MAP-kinase-kinase-kinase→MAP-kinase-kinase, eventually crosses into nucleus and activates transcription factors by phosphorylating them

Rb-

retinal blastoma protein, an important cancer suppressor, acts by binding to EF2 which is a transcription factor in cell division

EF2-

transcription factor in cell division which can be inhibited by Rb

ORCs, what are they, what phase?

- origin of replication complexes; (G1)

Cyclins E and A- what do they do? When do we see them?

produced towards the end of G1, activate CDK2

CDK2- function?

recruits preinitiation complex proteins (Cdc6, Cdt1) to ORCs

Cdc6- function and fate?

preinitiation complex protein destroyed by Cdk activity after triggering of DNA synthesis so DNA is not replicated more than one in a cycle

APC- how's it activated? what are its two main jobs?

Anaphase Promoting Complex; activated by M-Cdk, it inactivates securin which is an inhibitor of separase which promaotes the destruction of cohesin and allows attached chromatids to separate; also destroys CDK activity, ending M phase and initiating cytokenesis

Securin- what does it do?

inhibits separase

Seperase- what does it do?

promotes destruction of cohesin and subsequently the separation of attached chromatids

Cyclin B-

ubiquinated by APC for destruction, abolishes CDK activity ending M phase

Cyclin B

G1 checkpoint requirements-

if extracellular environment is favorable→ G1/S cyclin and Cdk synthesis and progression into S phase

if extracellular environment is favorable→ G1/S cyclin and Cdk synthesis and progression into S phase is called:

G1 checkpoint

G2/M checkpoint-

makes sure environment is favorable and all DNA is replicated for transition into M phase

M phase checkpoint-

ATM/ATR kinases activate if the detect DNA damage; they in turn activate Chk1/Chk2 kinases which phosphorylate p53; p53 is a transcription factor for CKI p21 which blocks Cdk activity and halts cell cycle for attempted DNA repair

M phase checkpoint

ATM/ATR kinases-

sense DNA damage during M phase checkpoint and activate Chk1/Chk2 kinases if damage exists

ATM/ATR kinase

Chk1/Chk2 kinases-

activated by ATM/ATR when DNA damage is present in M phase; the phosphorylate and activate p53

activated by ATM/ATR when DNA damage is present in M phase; the phosphorylate and activate p53:

Chk1/Chk2 kinases

What is the function of p53-

critically important protein activated by Chk1/Chk2 and upregulated when DNA damage is present in M phase. p53 functions as a transcription factor for CKI 21 which blocks Cdk activity and halts cell cycle

critically important protein activated by Chk1/Chk2 and upregulated when DNA damage is present in M phase. functions as a transcription factor for CKI 21 which blocks Cdk activity and halts cell cycle

p53

Spindle checkpoint-

unattached kinetochores activate Bub and MAD2 proteins which inhibit activation of APC thereby blocking anaphase initiation and Cdk destruction; this keeps the cell in pro/metaphase until all kinetochores can bind to microtubules and become aligned in metaphase plate

Spindle checkpoint

Bub-

protein activated by unattached kinetochores that inhibits APC and prevents progression into anaphase until all kinetochores are attached to microtubules

MAD2-

protein activated by unattached kinetochores that inhibits APC and prevents progression into anaphase until all kinetochores are attached to microtubules

Oncogenes-

mutated genes whose presence can stimulate the development of cancer

Tumor suppressor genes-

normal genes whose ABSENCE can lead to cancer

Cell Cycle Week 5 Holy Flashcards

(83 cards)