Meiosis Flashcards

1
Q

gametes are formed from

A

specialized diploid cells

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2
Q

______ ensures the production of haploid phase in the life cycle of sexually reproducing organisms whereas _____ restores the diploid phase

A

meiosis
fertilization

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3
Q

stages of meiosis

A

meiosis I
meiosis II

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4
Q

how many times does dna replicate in meiosis

A

once

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5
Q

how many cells are formed at the end of meiosis? what is their chromosomal state

A

four
haploid

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6
Q

stages of meiosis I

A

prophase I
metaphase I
anaphase I
telophase I
cytokinesis II

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7
Q

stages of meiosis II

A

prophase II
metaphase II
anaphase II
telophase II
cytokinesis II

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8
Q

which phase of the meiotic division is typically longer and more complex

A

prophase I

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9
Q

stages of prophase I

A

leptotene
zygotene
pachytene
diplotene
diakinesis

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10
Q

during which stage of prophase I do the chromosomes become visible under light microscope

A

leptotene

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11
Q

the compaction of chromosomes continues throughout which stage of prophase I

A

leptotene

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12
Q

during which stage does synapsis occur (prophase I)

A

zygotene

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13
Q

what is synapsis

A

chromosomes pair together

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14
Q

paired chromosomes during zygotene are called

A

homologous chromosomes

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15
Q

in zygotene, the chromosome synapsis is accompanied by the formation of complex structure called

A

synaptonemal complex

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16
Q

the complex formed by a pair of synapsed homologous chromosomes during zygotene is called

A

bivalent or tetrad

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17
Q

bivalents or tetrads are clearly visible during which stage of prophase I

A

pachytene

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18
Q

pachytene is characterized by

A

appearance of recombination nodules

19
Q

where are recombination nodules formed during pachytene

A

sites at which crossing over occurs between non-sister chromatids of the homologous chromosomes

20
Q

what is crossing over

A

exchange of genetic material between the homologous chromosomes

21
Q

enzyme involved in crossing over is called

A

recombinase

22
Q

in which stage of prophase I does the synaptonemal complex dissolve

A

diplotene

23
Q

during diplotene, after the synaptonemal complex is dissolved, do the bivalents separate from each other

A

yes except at the sites of recombination

24
Q

sites of crossover of chromosomes are called

A

chiasmata

25
Q

in oocytes of some vertebrates, how long does diplotene last

A

months or years

26
Q

terminalisation of chiasmata is seen in which stage of prophase I

A

diakinesis

27
Q

in which stage of prophase I are the chromosomes fully condensed

A

diakinesis

28
Q

during which stage of prophase I do the meiotic spindle assemble to prepare the homologous chromosomes for separation

A

diakinesis

29
Q

during which stage of prophase I does the nucleolus dissapear and the nuclear envelope disintegrate

A

diakinesis

30
Q

_______ of prophase I represents the transition to metaphase

A

diakinesis

31
Q

during which phase of meiosis I do the bivalent chromosomes align on the equatorial plate

A

metaphase I

32
Q

during which phase of meiosis I do the microtubules from the opposite poles of the spindle attach to the pair of homologous chromosomes

A

metaphase i

33
Q

during anaphase I, the _________ ________ separate while ______ _______ remain associated at their centromeres

A

homologous chromosomes
sister chromatids

34
Q

during which phase of meiosis I do the nuclear membrane and nucleolus reappear

A

telophase I

35
Q

after cytokinesis I, the state of two cells is called

A

dyad of cells

36
Q

although in many cases the chromosomes do undergo some dispersion, they do not reach the extremely extended state of the ______ nucleus

A

interphase

37
Q

the stage between the two meiotic divisions is called _____ and is generally short lived

A

interkinesis

38
Q

meiosis II represents

A

mitosis

39
Q

during which phase of meiosis II does the nuclear membrane disappear and the chromosomes again become compact

A

prophase II

40
Q

during which stage of meiosis II do the chromosomes align at the equator and the microtubules from opposite poles of the spindle get attached to the kinetochores

A

metaphase II

41
Q

during which phase of meiosis II do the chromosomes simultaneous split towards the opposite poles

A

anaphase II

42
Q

during which stage of meiosis II do the two groups of chromosomes get enclosed by a nuclear membrane

A

telophase II

43
Q

after cytokinesis II, the state of four cells formed is called

A

tetrad of cells