Cell Division Flashcards

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1
Q

how many chromosomes in humans?

A

46 chromosomes (23 homologous pairs)

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2
Q

what does a centrosome contain?

A

pair of centrioles

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3
Q

centrioles

A

produce spindle fibers that separate sister chromatids during anaphase

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4
Q

regulation of cell cycle

A
  • surface-volume ratio
  • genome-volume ratio
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5
Q

surface-volume ratio

A

if the volume ratio is small when cell is too big it makes cell exchange hard leading to cell death/division to increases surface area

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6
Q

genome-volume ratio

A

if it decreases, the cell exceeds ability of its genome to produce proteins needed to regulate the cell

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7
Q

cell cycle

A

interphases consiting of G1, S, G2 phase

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8
Q

when does interphase occur?

A

after mitosis and cytokinesis

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9
Q

G1

A

cell increases in size and G1 checkpoint ensures everything is ready for DNA synthesis

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10
Q

where does most cell growth occur?

A

G1 phase

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11
Q

S phase

A

DNA synthesis; 2nd molecule of DNA replicated from 1st into sister chromatids

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12
Q

where is DNA replicated?

A

S phase

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13
Q

G2 phase

A

rapid cell growth; preparation of genetic material for cell division, cell replicates organelles

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14
Q

G0 phase

A

inactive state of cells not actively growing/dividing
- nerve and & cardiac cells

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15
Q

when does the spindle apparatus form?

A

during prophase

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16
Q

what does each sister chromatid have?

A

kinetochore

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17
Q

where does kinetochore attach

A

MT attach’ MT don’t directly attach to chromosomes

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18
Q

prophase chromosomes/chromatids

A

46 chromosomes
92 chormatids

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19
Q

metaphase chromosomes/chromatids

A

46 chromosomes
92 chromatids

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20
Q

anaphase chromosomes/chromatids

A

92 chromosomes
92 chromatids

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21
Q

telophase chromosomes/chromatids

A

92 chromosomes
92 chromatids

22
Q

cytokinesis chromosomes/chromatids

A

46 chromosomes
46 chromatids

23
Q

prophase

A
  • nuclelus disassembles, nucleoulus disappears
  • chromatin condenses into chromosomes
24
Q

metaphase

A
  • chromosomes line up
  • each metaphase chromosome consists of 2 attached chromosomes
  • each chromatid complete with centromere and attached kinetochore
25
Q

anaphase

A
  • MT shorten and each chromosome is pulled apart into 2 chromatids
  • chromatids pulled to opposite poles disjunction
  • at the end each pole has a complete set of chromosomes
26
Q

telophase

A
  • nuclear envelope reforms
  • chromosomes decondense back into chromatin and nucleoli reappear
27
Q

meiosis

A

produces 4, non-identical haploid daughter cells from one diploid parent cell
* does this by repeating nuclear division twice

28
Q

meiosis 1

A

homologous chromosomes separate

29
Q

prophase 1 chromosomes/chromatids

A

46 chromosomes
92 chromatids

30
Q

prophase 1

A
  • spindle forms, nuclear envelope breaks down
  • chromosomes pair up lengthwise through synapsis forming tetrads to allow for crossing over
  • pairs linked with chiasmata
  • MT attache to chromosomes at kinetochore and move them towards metaphase plate
31
Q

chiasmata

A

regions where crossing over occurs

32
Q

metaphase 1 chromosomes/chromatids

A

46 chromosomes
92 chromatids

33
Q

metaphase 1

A
  • homologous chromosomes arranged at metaphase plate
  • independent assortment of chromosomes occur because arrangement is random
34
Q

anaphase 1 chromosomes/chromatids

A

46 chromosomes
92 chromatids

35
Q

anaphase 1

A

homologous chromosomes separate and spindle apparatus guides to opposite poles

36
Q

telophase and cytokinesis chromosomes/chromatids

A

46 chromosomes
92 chromatids

37
Q

telophase 1

A
  • homologous chromosomes are separates from each other to each end of cell
38
Q

cytokinesis 1

A

2 haploid daughter cells containing one chromosome for every homologous pair

39
Q

meiosis II

A

sister chromatids separate

40
Q

prophase ll chromosomes/chromatids

A

23 chromosomes
46 chromatids

41
Q

prophase ll

A

spindle apparatus forms and MT move chromosomes towards metaphase plate

42
Q

metaphase ll chromosomes/chromatids

A

23 chromosomes
46 chromatids

43
Q

metaphase ll

A
  • sister chromatids no longer genetically identical due to crossing over
  • chromosomes lined up at metaphase plate
44
Q

anaphase ll chromosomes/chromatids

A

46 chromosomes
46 chromatids

45
Q

anaphase ll

A
  • chromatids separate, move toward opposite poles
  • separated chromatids now chromosomes
46
Q

telophase ll and cytokinesis chromosomes/chromatids

A

46 chromosomes
46 chromatids

47
Q

telophase ll

A
  • nuclei formation and decondensing of chromosomes
  • result is 4 genetically distinct daughter cells
48
Q

sources of genetic variation

A
  • crossing over
  • independent assortment
  • random joining of gametes
49
Q

crossing over

A

non sister chromatids of 2 homologous chromosomes exchange genetifc material during prophase l

50
Q

independent assortment

A

during metaphase l, random orientation of chromosomes allows for production of gametes with diff. assortment of alleles

51
Q

genetic linkage

A

gene closer on chromosome more likely to be inherited together