2. Cell Cycle Flashcards

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1
Q

Diploid vs haploid

A

Two copies of each chromosome vs containing only one copy of each chromosome

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2
Q

Stages of interphase

A

G1, S, G2

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3
Q

What happens at G0 stage?

A

quiescence: Cell lives nml life, in stable state, performs reg cellular processes. Not part of interphase or cell cycle. Typically for non dividing cells (ex: neurons)

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4
Q

What happens at G1 stage?

A

Cells make organelles for energy and protein production like mito, ER, ribosomes; most cells = in this phase. Prepares for DNA replication too

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5
Q

How to transition from G1 stage to S stage?

A

Restriction point aka G1 checkpoint - checks for DNA damage, cell size, nutrients, growth factors. Are we ready to do S phase?

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6
Q

What happens at S stage?

A

Cell replicates chromosomes/chromatids into sister chromatids held by centromere

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7
Q

What happens at G2 stage?

A

Cell makes sure DNA is correctly replicated and there are enough organelles to make daughter cells; prepares for mitosis

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8
Q

What happens at M stage?

A

Mitosis

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9
Q

What happens at prophase?

A

Chromatin condense to chromosomes, centrioles move to opposite sides of cell and form spindle fibers; nuclear membrane dissolves

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10
Q

What happens at metaphase?

A

Chromosomes = attached to spindle fibers at kinetochores —> line up at metaphase/equatorial plate; involves kinesin

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11
Q

What happens at anaphase?

A

Centromeres split –> sister chromatids separate via 2 spindle fibers; involves kinesin.

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12
Q

What happens at telophase?

A

Spindle fibers disappear, nuclear envelopes reform, chrms relax (basically reverse prophase). Cleavage furrow initiates cytokinesis

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13
Q

What happens at cytokinesis?

A

Separation of cytoplasm and organelles. Initiated by cleavage furrow; occurs in telophase

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14
Q

Does meiosis occur in all cells?

A

No, only in gametocytes/germ cells

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15
Q

Other names for meiosis I and II

A

reductional division and equational division

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16
Q

Difference between meiosis I and II

A

Meiosis I separates homologous chrms to make haploid daughter cells; Meiosis II separates chrms similar to mitosis

17
Q

What happens in prophase I?

A

Same as prophase + homologous chrms intertwine at held by synaptonemal complex => synapsis –> each synaptic pair contains 4 chromatids => tetrad; crossing over at chiasmata occurs

18
Q

What happens at metaphase I?

A

Homologous pairs/tetrads line up at equatorial plate

19
Q

What happens at anaphase I?

A

Homologous chrms separate (segregation) to opposite sides of cell via single spindle fiber (as opposed to 2 spindle fibers in mitosis) => disjunction

20
Q

What happens at telophase I?

A

Nuclear membrane reforms, two sister chromatids still intact by centromere; interkinesis - chrms slightly uncoil

21
Q

What happens at prophase II, metaphase II, anaphase II, and telophase II?

A

Same as mitosis

22
Q

Purpose of G2 checkpoint?

A

Aka DNA damage checkpoint. Make sure DNA isn’t damaged and if DNA = replicated correctly; p53 = present. Are we ready to do M phase?

23
Q

centrosome vs centrioles vs asters

A

creates mitotic spindles and microtubules, they’re the main microtubules organizing centers and they anchor microtubules at one end and make sure they don’t depolymerize, assembly site for kinetochores; consists of 2 centrioles vs 2 centrioles w/in a centrosome, make spindle fibers vs star shaped centrioles + their associated microtubules

24
Q

How many times do somatic cells typically divide?

A

Enough till telomeres become too short to protect the DNA

25
Q

Which protein controls progression of a cell thru cell cycle?

A

Cyclin and cyclin dependent kinases

26
Q

What’s the mitotic spindle checkpoint?

A

Aka M checkpoint. In b/w metaphase and anaphase. Checks for chromosome attachment to spindle fibers at metaphase plate; are we ready to do anaphase?

27
Q

p53 vs TP53

A

Protein that suppresses propagation of cells with damaged DNA; promotes apoptosis, cell cycle arrest, and DNA repair pathways; present in G2/DNA damage checkpoint vs mutated form of p53, causes cancer

28
Q

What happens if cells can’t pass checkpoints?

A

If damaged DNA is the problem —> fix it np. Otherwise it can lead to apop, cancer - permanent activation of cell cycle, or senescence - permanent arrest of cell cycle (ie. Irreversible)