mitosis/meiosis Flashcards

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1
Q

prokaryotes divide by

A

binary fission

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2
Q

what do chromosomes look like in bacteria?

A

single circular chromosome

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3
Q

how do bacteria replicate their DNA?

A

from ORI sequence- create double strand- form septum, pinch in, voila! 2 daughter cells

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4
Q

eukaryotes have what kind of chromosomes (shape)

A

linear

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5
Q

unlike bacteria, chromosomes exist in ___ pairs

A

homologous

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6
Q

definition mitosis

A

chromosomal process that ensures each daughter cell gets exact, correct copy of genetic information

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7
Q

at what phase of mitosis do chromosomes become visible in light microscope

A

prophase

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8
Q

define DNA packing

A

Positively charged Histone proteins neutralize the negative charge on DNA

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9
Q

what is the beads on a string model?

A

Octamers of histone “core” proteins (nucleosomes) wrap DNA around themselves, giving it the appearance of “beads on a string”

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10
Q

when would you see the most condensed form of DNA

A

metaphase, on sister chromatids

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11
Q

what does 30 mm fiber refer to

A

the arrangement of packed nucleosomes and DNA

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12
Q

when would distinct chromosomes be visible

A

M phase of mitosis

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13
Q

4 phases of cell cycle

A

G1, G2 S, M,

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14
Q

what phase are non dividing cells in? can you give an example?

A

G0. liver cell

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15
Q

Interphase is what 3 phases

A

G1 + G2 + S

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16
Q

G1

A

rapid growth and metabolic activity of mitosis

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17
Q

G2

A

growth and preparation for cell division

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18
Q

S phase

A

DNA replication and growth

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19
Q

what kind of phase are neurons always in?

A

G0 - nondividing

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20
Q

what significant event happens in S phase?

A

synthesis of DNA

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21
Q

describe a replication fork and when you’d find it

A

in S phase, as you replicate DNA, you go from single strand -> double strand. as this is happening, bidirectionally, you get a replication bubble and fork

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22
Q

Kinetochore

A

Kinetochore structures (made of proteins) are the attachment sites for microtubules at the centromere regions

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23
Q

telomeres

A

ends of chromatids/chromosomes

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24
Q

what do you call DNA in the replicated form

A

‘sister chromatids’

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25
Q

how do you identify chromosomes for a karyotype?

A

based on their band patterns, gleaned from electrophoresis. line up from largest->smallest

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26
Q

name for non-sex cells

A

somatic cells

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27
Q

what phase of mitosis is essentially a reverse of prophase

A

telophase- rebuild nuclear envelope, recondense

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28
Q

when would DNA convert back to regular old chromatin?

A

after cytokinesis

29
Q

what does the nucleus do in interphase?

A
  1. Ribosomal RNA being copied from RNA into DNA form to assemble a ribosome
30
Q

what happens in interphase nucleus that would affect the chromatin?

A

ex- inactive B cell (in lymphocyte) and it has a lot of heterochromatin. After it is activated to participate in immune response, the gene pattern changes and now we have a lot of euchromatin instead of heterochromatin

31
Q

___ are the intermediate filaments that support the inside of nuclear envelope

A

nuclear lamins

32
Q

__ chromosomes are in each cell during mitosis

A

46

33
Q

kinetochore complex

A

centrosome + microtubule site of attachment

34
Q

what’s the pac-man complex?

A

to move the chromosome towards the poles for anaphase, the kinetochore complex ‘eats’ the microtubules- aka depolymerizes the tubulin in the microtubules

35
Q

aster fibers and who has them

A
  1. only animals have aster fibers
  2. they are a type of mitotic spindle that are unattached microtubules hanging off the centriole
36
Q

do plant cells have centrioles?

A

no

37
Q

kinetochore microtubules

A

mitotic spindle running ‘pole to kinetochore’. found in both plant and animal cells

38
Q

polar microtubules

A

mitotic spindle running pole to pole. found in both plants and animals

39
Q

what proteins perform the cleavage taking telephase to cytokinesis?

A

actin filaments + myosin motors act to contract the cleavage furrow until the cell pinches off

40
Q

reduction divsiion

A

stage of meiosis I , anaphase I, where the pairs of chromosomes separate (3 replicated chromes on each side of cell) centromeres have NOT split. this is the stage where the cell finally goes from 46-> 23 chromosomes

41
Q

in anaphase II, how many chromosomes are at each pole

A

23

42
Q

when does synapse occur?

A

meiosis : in prophase I- line up with homologous chromosomes, crossing over occurs @ chiasmata

43
Q

what are the 2 parts of anaphase

A

anaphase A: chromosomes pulled poleward

anaphase B: poles pulled apart

44
Q

when in mitosis does gene activity resume?

A

telophase

45
Q

when in mitosis does nucleolus reappear?

A

telophase

46
Q

phragmoplast

A
  1. instead of pinching in, plants create a cell plate in the middle of cell
    1. grouping of small vesicles produced in the golgi that move along microtubules to the middle of cell
    2. new golgi/ER complex in replicating plant cell is the phragmoplast
47
Q

when you enter prophase I of meiosis, are chromosomes already replicated?

A

yes

48
Q

when in meiosis does crossing over occur

A

prophase I

49
Q

what event precludes crossing over

A

synapse

50
Q

The Thompson seedless grape is triploid, with three copies of each chromosome. Which phase of the cell cycle would you expect triploid cells to be unable to complete.

A

homologous chromosomes must pair in meiosis I. Triploid cells would be unable to complete meiosis I.

51
Q

The stage of meiosis where cells become haploid

A

Separation of homologous pairs occurs at anaphase I. Even though each chromosome has two chromatids, the total number of chromosomes is 23 for humans after anaphase I of meiosis I. Recall that the number of chromosomes is determined by the number of centromeres

52
Q

name the 3 mitotic spindle fibers

A
  1. aster fibers
  2. pole to pole fibers
  3. pole to kinetochore fibers
53
Q

telocentric

A

centromere hangs out at end of chromosome

54
Q

name for when centromere is in middle of chromosome

A

metacentric

55
Q

name for when centromere is at top of chromosome

A

acrocentric

56
Q

when would gene expression happen

A

interphase

57
Q

of centrioles present in metaphase

A

4; 2 at each end (count each guy as its own!)

58
Q

number of chromosomes/chromatids present at metaphase 2

A

chromosomes: n
chromatids: 2n

59
Q

chromosomes / chromatids: anaphase 2

A

46, 46

60
Q

chromosomes/chromatids: metaphase I

A

2n, 4n

61
Q

chromosomes/chromatids: prophase I

A

2n, 4n

62
Q

chromosomes/chromatids prophase II

A

n, 2n

63
Q

mitosis: # chromosomes/chromatids in metaphase

A

2n, 4n

64
Q

how does division in binary fission work

A

•split in two between plasma membrane attachment sites (involves forming a septum and pinching-in)

65
Q

specific structure to which microtubules attach

A

kinetochore

66
Q

test cross (who vs who?)

A

SsYy x ssyy

67
Q

amount dna division versus prophase

A

1:2 (you get sister chromatids in prophase, 2x the DNA!)

68
Q

how many chromatids are present in anaphase?

A
  1. they are all replicated, no single chromatids