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Genetics 380 > Cell Cycle, Mitosis, & Meiosis > Flashcards

Cell Cycle, Mitosis, & Meiosis Flashcards

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Biology 101 flashcards
1
Q

set of proteins the cell possess…

A

…determines the functions the cell can perform

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2
Q

G1

A

stockpile nucleotides, ATP, enzymes to replicate DNA

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3
Q

S

A

replicate DNA

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4
Q

G2

A

synthesize microtubules and other proteins needed for cell division, stockpile ATP and enzymes for mitosis/meiosis

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5
Q

M

A

mitosis or meiosis

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6
Q

G0 (G Zero)

A

cell stops replicating and dividing

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7
Q

reasons for G zero phase

A

suffered damage to DNA; lack of growth factors, nutrients or other molecules that are necessary for cell cycle to continue in environment; telomeres are short (time for cell to die and be replaced); some go to G0 after fully differentiated and remain in G0 until they die (neurons lack centrioles so they can’t divide red blood cells lack nuclei)

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8
Q

specifics of G1

A

phosphorylation of certain proteins (ex: retinoblastoma RB protein); at the end of G1 cell makes sure it has stockpiled all the enzymes it needs to replicate DNA before it goes into S phase

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9
Q

specifics of G2

A

cell must accumulate certain level of complex called mitosis-promoting factor (MPF) and activate it by dephosphorylation in order to enter the M phase; at end of G2 cell checks for DNA damage presence of DNA damage keeps MPF inactive and halts the cell in G2; cell also checks length of telomeres

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10
Q

telomere length

A

indicator of cell age; telomeres shorten every cell cycle

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11
Q

spindle assembly checkpoint

A

during late metaphase cells checks to be sure every chromosome is properly aligned at equatorial plane and that every centromere has been contacted by a spindle fiber; everything alined properly = MPF will be inactivated so cell can . proceed toward end of mitosis

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12
Q

stages of mitosis

A

prophase, prometaphase, metaphase, anaphase, telophase (cytokinesis)

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13
Q

cytokinesis

A

occurs during telophase - cytoplasm and organelles are divided between 2 daughter cells

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14
Q

end of interphase

A

spindle fiber apparatus (green/yellow) is not yet organized; chromatin is decondensed - no discernable chromosome in the nucleus; nuclear membrane is intact

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15
Q

prophase

A

chromatin condenses into visible chromosomes and migrates toward equatorial plate; DNA was replicated in S phase = each chromosome now has 2 sister chromatids; by late prophase you can see 2 separate sister chromatids under microscope; nuclear envelope disintegrate centrosomes move to poles of dividing cell; spindle fibers grow out of the centrosomes toward centromeres of chromosomes

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16
Q

early prophase

A

chromosomes begin to condense; centrosomes begin to move toward opposite poles of dividing cell

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17
Q

late prophase/prometaphase

A

centrosome have migrated to poles; chromosomes are condensed; nuclear membrane is gone; spindle fibers are reaching in and binding to chromosomes

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18
Q

metaphase

A

at the end chromosomes are in most condensed configuration and aligned at equatorial plane; nuclear envelope still disintegrated; spindle fibers bound to kinetochore at centromere of each chromatid - binding occurred during late prophase; cell undergoes spindle-assembly checkpoint to be sure every chromatid has been bound by spindle fiber

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19
Q

late metaphase

A

chromosomes are aligned at equator; spindle fibers are bound to the chromosomes via kinetochores; each chromatid is bound by spindle fiber

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20
Q

anaphase

A

sister chromatids separate and are pulled toward opposite poles; each chromatid is now chromosomes; nuc envelope still disintegrated; centrosomes and spindle fibers still very visible

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21
Q

middle of anaphase

A

spindle fibers have bound chromosomes by connecting to kinetochores at their centromeres and are drawing chromosomes apart

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22
Q

separase

A

degrades cohesin to allow separation of sister chromatids which allows sister chromatids to segregate apart during anaphase

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23
Q

cohesin

A

hold sister chromatids together at centromere until enzyme separase degrades cohesin (end of metaphase - beginning of anaphase)

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24
Q

dynein

A

motor protein that pulls the sister chromatids apart; sits on two spindle fibers and pulls on 2 spindle fibers that are connected to chromosomes

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25
Q

telophase

A

sister chromatids (now chromosomes) have been pulled completely toward 2 poles during anaphase - no movement necessary; chromatin decondenses; nuclear envelope reforms; spindle fibers degenerate to some degree; new cell membrane material is synthesize so 2 daughter cells are now separate functional cells

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26
Q

early mid telophase

A

nuclear membrane not yet reformed; chromatin still somewhat condensed; cells only beginning to cleave apart, new cell membrane not yet visible

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27
Q

after S phase of interphase

A

each chromosome contains 2 sister chromatids

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28
Q

number of chromosomes =

A

number of centromeres; each chromatid is separate molecule of DNA

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29
Q

2 sister chromatids held together at centromere =

A

one chromosome but 2 DNA molecules

30
Q

meiosis vs. mitosis

A

only spermatogonia and oogonia undergo meiosis during M phase other cells undergo mitosis

31
Q

meiosis

A

produces 4 haploid daughter cells (one set of chromosome per cell) while mitosis produces 2 diploid daughter cells (2 sets of chromosomes per cell)

32
Q

recombination

A

occurs between homologous chromosomes during meiosis which results in child inheriting some chromosomes that contain combination of gene alleles that came down from the grandfather and grandmother

33
Q

chromosomes doubled in interphase

A

held together along entire length by protein cohesin; enzyme separase will dissolve cohesin to allow 2 homologous chromosomes to separate during anaphase I and sister chromatids to separate during anaphase II

34
Q

end of interphase

A

spindle fiber apparatus (green/yellow) is not yet organized; chromatin is decondensed - no discernable chromosomes in nucleus; nuclear membrane intact

35
Q

stages of meiosis prophase I and prometaphase I

A

leptotene, sygotene, pachytene, diplotene, diakinesis; non sister homologous chromatids (one from each member of the homologous chromosome pair) physically cross over at points of contact and exchange material (i.e. homologous recombination occurs)

36
Q

leptotene

A

step one of prophase I: chromatin condenses

37
Q

zygotene

A

step 2 of prophase I: chromatin condenses homologous chromosomes pair up and engage in synapsis (aligning very close to each other) to produce bivalents aka tetrads

38
Q

bivalents

A

2 chromosomes

39
Q

tetrads

A

4 chromatids

40
Q

pachytene

A

step 3 of prophase I: chromatin condenses synaptonemal complex develops between homologous chromosomes (homologous chromosomes come into contact w each other at one or more place sin each p and q arm)

41
Q

diplotene

A

step 4 of prophase I: 2 chromosomes in each bivalent begin to separate but remain joined at the chiasma (i.e. the places where the crossing over took place)

42
Q

diskinesis

A

step 5 of prophase I: chromatin condenses further the 2 chromosomes in the bivalent separate farther apart the 2 chromosomes now remain joined only at the ends

43
Q

early prophase I

A

centrosomes begin to move toward opposite poles of dividing cell; chromosomes begin to condense

44
Q

last prophase I (prometaphase I)

A

centrosomes have migrated to the poles; chromosomes now condensed; nuclear membrane has disappeared; spindle fibers are reaching in to bind chromosomes

45
Q

homologous recombination in prometaphase I

A

original chromosome pair in spermatogonium or oogonium; chromosomes double 2 of the 4 chromatids cross over; recombination occur 2 chromatids exchange portions; after 2 cell divison gametes w non recombinant chromosomes and gametes w recombinant chromosome

46
Q

metaphase I

A

bivalents are aligned in tetrads along equatorial plane; spindle fibers connect to chromosomes by the kinetochores at their centromeres; cell checks to be sure every chromatid is bound by spindle fiber

47
Q

late metaphase I

A

chromosomes are aligned at the equator; spindle fibers are binding the chromosomes

48
Q

anaphase I

A

enzyme separase degrades cohesin that hold 2 homologs together but leaves cohesin that is holding sister chromatids together at the centromere intact; 2 chromosomes in each bivalent migrate apart from each other toward opposite poles of diving cell

49
Q

middle of anaphase I

A

spindle fibers draw chromosomes apart

50
Q

protein shugoshin

A

prevent separation of sister chromatids; protects cohesin at centromeres only from degradation by separase this holds sister chromatids together at centromeres during anaphase I of meiosis so they don’t separate until anaphase II; shugoshin must be degraded during metaphase II so sister chromatids can separate during anaphase II

51
Q

telophase I

A

chromosomes have migrate completely to opposite poles; cytokinesis

52
Q

early-mid telophase

A

nuclear membrane has not yet reformed; chromatin is still somewhat condensed; cells only begin to cleave apart new cell membrane is not yet visible

53
Q

interkinesis

A

nuclear membrane reforms spindle fibers degenerate chromatin decondenses; several proteins are necessary for chromatin condensation in prophase II get phosphorylated and assembled into complexes including some of the cohesins (there are several version of cohesin) and condensin II

54
Q

reduction division

A

first cell division; reduces number of chromosomes in cell by half

55
Q

equational division

A

second cell division; no change in the number of chromosomes per cell

56
Q

prophase II

A

chromatin condenses nuclear envelope degenerates spindle fibers form

57
Q

metaphase II

A

chromosomes align at equatorial plane and spindle fibers connect to chromosomes (at kinetochore at the centromere); half the chromatids are recombinant chromatids and half are nonrecombinant chromatids

58
Q

anaphase II

A

sister chromatids migrate apart from each other toward opposite poles of the diving cell

59
Q

telophase II

A

nuclear membrane reforms, spindle fibers disappear, chromatin decondenses

60
Q

products of meiosis

A

chromatin is now decondensed; if chromosomes are drawn as they would appear if they recondensed you can see how half your gametes contain nonrecombinant chromosome from that pair and the other half contain recombinant chromosomes

61
Q

genetic diversity

A

maintained by meiosis - recombination creates new gene allele combinations on chromosomes

62
Q

gene conversion

A

occurs when the sequence of one allele of a gene is changed and actually becomes the sequence of other allele

63
Q

heteroduplex DNA

A

strand from one homolog bound to a strand from the other homolog at the end of recombination

64
Q

homologous recombination & gene conversion model one

A

(1) single strand break in each homolog broken ends join w broken ends of other homolog (2) strands that reached across and connected w strand from other homolog now return to original place Holliday junction moves down chromosome (no DNA synthesis necessary)

65
Q

homologous recombination & gene conversion model two

A

(1) double strand break in one homolog some nucleotides are removed from each strand (2) one strand of each homolog is used as template to synthesize DNA to fill gap in strand from the other homolog

66
Q

heterozygous gene & heteroduplex

A

bubble in heteroduplex DNA bc there will be places where the bases are not complementary to each other and will not bond to each other; DNA repair proteins recognize bubbles like these as things that need to be repaired = cut mismatched bases out of one of DNA strands then use remaining strand as template to synthesize new DNA; for each mismatch it is equally likely that the red strand or blue strand will be cut out

67
Q

spermatogenesis

A

produces 4 viable sperm

68
Q

oogenesis

A

produces one viable egg

69
Q

spermatogenesis & oogenesis

A

right after fertilization zygote/embryo undergoes several rounds of cleavage & cell division w no replication of cytoplasm & organelles; sperm has donated only its DNA and centrosome so all cytoplasm and organelle that are available to be divided among newly created cells come from the egg; when cell divides all cytoplasm and organelles migrate into one daughter cell; cell that gets the cytoplasm and organelles becomes egg other daughter cell is polar body - usually dies off

70
Q

divisions of oogenesis

A

1st meiotic divison = 2ndary oocyte and 1st polar body (both haploid each chromosome has 2 chromatids); 2nd meiotic division creates ovum and 2nd polar body (both are haploid; each chromosome contains one chromatid)

71
Q

time course of sperm

A

men make sperm at puberty and make them continuously for a variable time period

72
Q

time course for oogenesis

A

primary oocytes begin meiosis from 7 months gestation to shortly after birth but they stop at diplotene; meiosis resumes at puberty but only a handful of primary oocytes resume meiosis each month and they stop in metaphase II; meiosis finishes after fertilization occurs

Genetics 380 (11 decks)

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