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Genetics 1 > Topic 1: Cell Division > Flashcards

Topic 1: Cell Division Flashcards

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1
Q

when did the early study of genetics start?

A

1865

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2
Q

genes control gene ____ of DNA to RNA, and therefore ______ to proteins

A
  1. transcription
  2. translation
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3
Q

genes are contained in _____

A

chromosomes

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4
Q

genetic information can also be contained within ______ (plants) and _____ (plants&animals)

A
  1. chloroplasts
  2. mitochondria
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5
Q

what are the three main subdisciplines of genetics?

A

transmission genetics
evolutionary genetics
molecular genetics

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6
Q

mitosis creates ______

A

two identical daughter cells

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7
Q

in what kind of cells does mitosis occur?

A

somatic cells

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8
Q

each somatic cell is ____N (______)

A
  1. 2N
  2. diploid
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9
Q

if human cells are diploid, how many chromosomes do humans have if their diploid state is 2N=46?

A

23 chromosomes

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10
Q

meiosis creates _____

A

four unique haploid cells

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11
Q

in what kind of cells does meiosis occur?

A

germ-line cells, to produce gametes!

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12
Q

what are the six stages of mitosis?

A

interphase
prophase
prometaphase
metaphase
anaphase
telophase/cytokinesis

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13
Q

in _____,
1. chromosomes are diffuse and not visible
2. chromosomes are duplicated
3. nuclear envelope still encloses the nucleus
4. two centrosomes are in the cytoplasm
5. microtubules begin to extend

A

interphase

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14
Q

in ______,
1. chromosomes begin to condense and become visible
2. sister chromatids attached via centromeres visible
3. pair centrosomes move to the poles
4. microtubules extend from centrosomes to form the mitotic spindle
5. nucleolus disappears

A

prophase

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15
Q

in ______,
1. nuclear envelope begins to breakdown
2. mitotic spindle attaches to kinetochores of the sister chromatids
3. microtubules begin exerting pulling forces in both directions
4. chromosomes begin to move to center of the cell
5. cohesion proteins bind sister chromatids together
6. nonkinetochore and astral microtubules stabilise the cell

A

prometaphase

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16
Q

why do cohesion proteins bind sister chromatids together in prometaphase?

A

to prevent them from separating early!

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17
Q

in ______,
1. chromosomes are fully condensed
2. chromosomes align to metaphase plate
3. sister chromatids are still attached to kinetochore microtubules extended from centrosomes
4. mitotic spindle fully developed

A

metaphase

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18
Q

in ______,
1. sister chromatids separate
2. daughter chromosomes move towards opposite poles and congregate at centrosomes
3. non-kinetochore and astral microtubules polymerise, elongating the cell

A

anaphase

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19
Q

“_______”: sister chromatids separate

A

disjunction

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20
Q

in _____, cohesion proteins break down and kinetochore microtubules depolymerise

A

disjunction (when sister chromatids separate in anaphase)

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21
Q

in ______ & ______,
1. non-kinetochore microtubules continue polymerising (elongating the cell)
2. nuclear envelope redevelops
3. chromosomes decondense
4. cytokinesis divides the cytoplasmic contents equally between daughter cells
5. nucleolus reforms to continue creating proteins/ribosomes again

A

telophase/cytokinesis

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22
Q

what does cytokinesis form in plants to divide the two daughter cells? in animals?

A
  1. cell plate
  2. contractile ring and cleavage furrow
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23
Q

during mitosis the number of chromosomes _____

A

doesn’t change

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24
Q

during mitosis, the number of chromatids _____

A

doubles in S phase, goes back to normal after anaphase

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25
Q

if we have 2ng of DNA in G1, we have ____ after S phase and ____ after anaphase (M phase)

A
  1. 4ng
  2. 2ng
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26
Q

_________, pass if cell size is adequate, nutrients are available, presence of growth factors

A

G1 checkpoint

27
Q

what do growth factors do?

A

regulate cyclin kinases

28
Q

______, pass if DNA replication is complete and base-pair mismatches/errors are removed

A

S-phase checkpoint

29
Q

_____, pass if cell size is adequate, chromosome replication is complete

A

G2 checkpoint

30
Q

_______, pass if all chromosomes are attached to the mitotic spindle

A

metaphase checkpoint

31
Q

which 3 of the 4 main checkpoints does a cell HAVE to pass to continue on in the cell cycle?

A

G1, S-phase, G2

the cell can still function if it doesn’t pass the metaphase checkpoint

32
Q

meiosis has ___ rounds of cell division

A

2

33
Q

is there DNA replication between meiosis I and II?

A

no!

34
Q

_____ -homologous chromosomes separate, ploidy level is halved

A

meiosis I

35
Q

____- sister chromatids separate

A

meiosis II

36
Q

which phase of meiosis is most similar to mitosis?

A

meiosis II

37
Q

what are the three main hallmark events of meiosis I?

A
  1. homologous chromosome pairing
  2. crossing over between homologous chromosomes
  3. segregation of homologous chromosomes
38
Q

what does chromosome synapsis mean?

A

crossing over!

39
Q

crossing over between homologous chromosomes results in ____

A

recombination

40
Q

where does recombination occur?

A

at chiasmata (crossing-over sites)

41
Q

what are the five sub-stages of prophase I?

A

leptotene and zygotene, pachytene and diplotene, diakinesis

42
Q

______: chromosomes are duplicated, chromosomes condense but not visible, centrosomes migrate to poles, spindle fibers produced

A

leptotene

43
Q

_____: chromosomes continue condensing, homologous pairs enter synapsis (forming the synaptonemal complex), meiotic spindle forms, and the nuclear envelope begins to break down

A

zygotene

44
Q

what is the synaptonemal complex?

A

3-layer structure that forms during prophase I, tightly binds non-sister chromatids of homologous chromosomes

45
Q

______: chromosome condensation is partially complete, synapsed homologs are seen as bivalents (tetrads), crossing over occurs between non-sister chromatids (formation of chiasmata), kinetochore microtubules attach to the kinetochores, nuclear envelope breakdown continues

A

pachytene

46
Q

_____: crossing over is complete, synaptonemal complex dissolves but chiasmata remain, tetrads are completely visible, the nuclear envelope is fully dissolved

A

diplotene

47
Q

_____: meiotic spindle established, homologous chromosomes tethered to poles via spindle fibers, nuclear envelope fully degraded, tetrads move to cell middle

A

diakinesis

48
Q

______: tetrads align at to the metaphase plate, homologous pairs are tethered to opposite poles, kinetochores of sister chromatids are attached to the same centromere and joined by cohesion proteins, chiasmata linking non-sister chromatids are broken

A

metaphase I

49
Q

metaphase I allows recombination via ______

A

independent assortment

50
Q

independent assortment allows for ____ different combinations (where n= number of homologous pairs)

A

2^(n-1)

51
Q

anaphase I (_____ of alleles)

A

segregation

52
Q

______: kinetochore microtubules depolymerise, disjunction occurs (pulling homologies to opposite poles), sister chromatids remain attached by cohesion, ploidy level has now been reduced by half

A

anaphase I

53
Q

_____ & ________: nuclear membrane re-form around chromosomes, chromosomes partially decondense, cytokinesis divided the cytoplasmic contents (which may now be uneven), progeny cells are now haploid

A

telophase I and cytokinesis

54
Q

___:
1. nuclear envelope breaks down
2. centrosomes duplicate and migrate to poles
3. microtubules form
4. chromosomes recondense

A

prophase II

55
Q

_____:
1. sister chromatids attached to kinetochore
2. align at metaphase plate

A

metaphase II

56
Q

_____:
1. sister chromatids separate, breakdown of cohesion proteins
2. kinetochore microtubules deploymerise (shorten)
3. sister chromatids move to opposite poles

A

anaphase II

57
Q

_____ & _____:
1. chromosome migration complete
2. chromosomes decondense
3. nuclear envelope reforms
4. cytokinesis divided the cytoplasm

A

telophase II and cytokinesis

58
Q

chromatids are _____ in S-phase, then ____ in meiosis I and then _____ again in meiosis II

A
  1. doubled
  2. halved
  3. halved
59
Q

number of chromosomes stay _____ in S-phase, then are _____ in meiosis I and remain ____ in meiosis II

A
  1. the same
  2. halved
  3. halved
60
Q

how many chromosomes and chromatids does a gamete have?

A

23 chromosomes, 23 chromatids

61
Q

_______= failed chromosomal separation

A

nondisjunction

62
Q

where does nondisjunction occur?

A

meiosis I or II

63
Q

what does nondisjunction cause?

A

aneuploidy, missing or extra chromosomes

64
Q
A

Genetics 1 (11 decks)

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