Exam 4 Part 1 Flashcards

1
Q

interphase

A

includes G1, S, G2 phases. Cell increases in size, DNA is replicated, and centrosome duplicated

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2
Q

prophase

A

duplicated chromosomes (each consisting of two closely associated sister chromatids), condense. The mitotic spindle assembles between the two centrosomes, which have begun to move apart.

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3
Q

prometaphase

A

breakdown of the nuclear envelope. Chromosomes can now attach to spindle microtubules via their kinetochores and undergo active movement

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4
Q

metaphase

A

chromosomes are aligned at the equator of the spindle, midway between the spindle poles. The kinetochore microtubules on each sister chromatid attach to opposite poles of the spindle

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5
Q

anaphase

A

sister chromatids synchronously separate and are pulled slowly toward the spindle pole to whichthey are attached. The kinetochore microtubules get shorter, and the spindle poles also move apart, both contributing to chromosome segreation

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6
Q

telophase

A

two sets of chromosomes arrive at the spindle poles. A new nuclear envelope reassembles around each set, completing the formation of two nuclei and marking the end of mitosis. The division of the cytoplasm begins with the assembly of the contractile ring

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7
Q

cytokinesis

A

cytoplasm is divided in two by a contractile ring of actin and myosin filaments, which pinches the cell into two daughters, each with one nucleus

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8
Q

quiescent

A

just living and functioning - when a cell is in G0 phase

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9
Q

G1

A

growing in size, increasing materials

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10
Q

S phase

A

synthesis phase - when DNA is replicated

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11
Q

G2

A

more growth, checking the cell before entering mitosis

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12
Q

what the cell cycle must accomplish

A

events associated with each phase must be performed in the correct time and sequence
must respond to extracellular and intracellular cues
each phase must be completed before the next begins

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13
Q

three major checkpoints

A

G1 - is environment favorable? is DNA damage free? (committed step)
G2 - DNA replicated? Damage reparied? Enough materials?
M- Are all chromosomes attached to spindle? Enough materials present?

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14
Q

How to study cell cycle genes when knocking them out disrupts cycle?

A

Can make temp sensitive mutants or an induced knockout (found a kinase involved)
can also examine the proteins and ID cell cycle promoting factors (xenopus eggs)

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15
Q

2 proteins important for mitosis

A

Cyclin dependant kinases (Cdk)

Cylins

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16
Q

cyclins

A

control the phosphorylation of Cdks
cyclin binding activates Cdk
concentration is cyclic

17
Q

cdk

A

cyclin dependant kinases

concentration stable throughout cycle, inactive without a cyclin

18
Q

Regulation of cdk

A

degradation of cyclin
phosphorylation
inhibitor

19
Q

regulation of cdk by degradation of cyclin

A

ubiquitin binds to cyclin which is a tag to take it to the lysosome
without cyclin, cdk is not active
degradation allows for the concentration occilation

20
Q

regulation of cdk by phosphorylation

A

inhibitory kinase adds a phosphate to an activated cdk which changes its conformation
the phosphorylation is inhibatory (switches off)

21
Q

regulation of cdk by inhibitor

A

inhibitory protein binds to entire activated cdk complex and inactivates it
ex. p27, p53

22
Q

why so much cdk regulation?

A

important to regulate number of cells (too much or too little), need to repair DNA damages