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Biomedical Genetics > Cell Division: Mitosis & Meiosis > Flashcards

Cell Division: Mitosis & Meiosis Flashcards

1
Q

What is Karyokinesis?

A

partition of the nucleus/formation of 2 new nuclear membranes

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2
Q

What is Cytokinesis?

A

division of the cytoplasm and cell membrane/formation of 2 new cell membranes

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3
Q

What are the two phases of the cell cycle?

A

Interphase and Mitosis

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4
Q

What are the different phases within interphase?

A

G1, S, G2

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5
Q

What are the phases within mitosis?

A

prophase, metaphase, anaphase, telophase

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6
Q

How long is a cell in the interphase and mitosis stages?

A

Interphase- 90% ~20hr
Mitosis- 10% ~2hr

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7
Q

What is involved in the G1 phase?

A

cell growth, transcription, translation, and G0

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8
Q

What is involved in the S phase?

A

(synthesis); DNA replication

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9
Q

What is involved in the G2 phase?

A

Check for any DNA damage and repair

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10
Q

What is involved in Mitosis?

A

separation of sister chromatids, karyokinesis, and cytokinesis

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11
Q

In the cell cycle, when is a nuclear membrane present?

A

G1 to prophase

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12
Q

In the cell cycle, when are there no visible chromosomes?

A

G1 through G2

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13
Q

What is a checkpoint in the cell cycle?

A

transition from step to step

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14
Q

What are checkpoints regulated by?

A

> 1000 genes/proteins and many microRNAs

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15
Q

What are cycllins?

A

groups of proteins; level of the proteins changes throughout the cycle

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16
Q

What are cyclin dependent kinases?

A

they attach phosphates to other proteins and activate them

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17
Q

What are phophatases?

A

they remove protein groups

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18
Q

What so transcription factors do?

A

specific ability to bind directly to DNA and trigger transcription of certain genes

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19
Q

What are the chromatin modifying proteins? (5)

A

TOPOisomerase II
Cohesin
Separase
Securin
Microtubules Associated Proteins (MAPs)

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20
Q

What is the function of TOPOisomerase II?

A

unwinds DNA double helix

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21
Q

What is the function of cohesin?

A

keeps sister chromatids together

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22
Q

What is the function of separase?

A

cleaves cohesin and separates centromeres

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23
Q

What is the function of securin?

A

triggers anaphase, transports separase to the nucleus

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24
Q

What are some examples of MAPs?

A

kinesins, dyneins

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25
Q

In the S phase, how many different “phases” are there and what are they?

A

2: early replication and late replication

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26
Q

What is present during the early replication “phase” of the S phase?

A

transcriptionally active DNA

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27
Q

What is present during the late replication “phase of the S phase?

A

inactive DNA; heterochromatin

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28
Q

What is the result of mitosis?

A

equal division of genetic material and the formation of two new daughter cells

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29
Q

What occurs during prophase?

A

chromosomes begin to condense, sister chromatids become visible, nucleolus disintegrates, nuclear membrane breakdown

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30
Q

What is a centrosome?

A

microtubule organizing center. Composed of centrioli which divide and move apart

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31
Q

What occurs during prometaphase?

A

chromsomes move towards midline and condensing continues, sister chromatids become visible, formation of spindles, no nuclear membrane, and chromosomes attach to spindles

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32
Q

What does DNA decatenation mean?

A

the sister chromatids become visible

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33
Q

What occurs during metaphase?

A

maximum chromosome condensation, chromosomes attach to spindles at both poles, kinetochores under tension

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34
Q

What does colchicine do?

A

“spindle poison” causes damage to the spindles and arrests mitosis

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35
Q

What occurs during anaphase?

A

split of the centromeres, separation of the sister chromatids, sister chromatids pulled apart and moved to separate poles

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36
Q

After disjunction, what are sister chromatids called?

A

daughter chromosomes

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37
Q

What occurs during telophase?

A

daughter chromosomes arrive at the poles, karyokinesis, decondensation pf chromosomes, cytokinesis

38
Q

How many checkpoints are there in the cell cycle?

A

4

39
Q

What is the G1-S checkpoint for?

A

whether or not the cell qualifies for cell division

40
Q

What is the S-G2 checkpoint for?

A

TO check that all the DNA is replicated and that it has only been replicated once

41
Q

What is the G2-M checkpoint for?

A

To check if the DNA is damaged and repair it

42
Q

What is the M checkpoint for?

A

To check that spindle is well attached to the kinetochore

43
Q

What is the biological function of Mitosis?

A
  • replicate genetic material and divide it equally/without mistakes between daughter cells
  • growth, replacement, and maintenance of cells
44
Q

What are the essentials of mistosis?

A
  • homologous chromosomes behave independently from each other
  • disjunction/separation of sister chromatids
  • chromosome # before=chromosome # after
45
Q

Which type of cells undergo diploid mitosis and what is the purpose?

A

Somatic cells; for growth and development

46
Q

What type of cell undergo haploid meiosis and what is the purpose?

A

Germ cells; for sexual reproduction

47
Q

What happens to the genetic material in cells that under go mitosis?

A

Remains the same

48
Q

What happens to the genetic material in cells that undergo meiosis?

A

It is cut in half

49
Q

How many stages are in Meiosis Prophase I and what are they?

A

There are 5
1. leptonema
2. zygonema
3. pachynema
4. diplonema
5. diakinesis

50
Q

What happens in the leptonema stage of prophase I?

A

stage 1: chromatin condenses and is the start of homology search

51
Q

What are chromomeres?

A

bread like irregularly spaced condensations

52
Q

What happens in the zygonema stage of prophase I?

A

stage 2: continuation of condensation, homologs find each other, formation of bivalents, start of synapsis

53
Q

What are bivalents?

A

two homologous chromosomes

54
Q

What does synapsis mean?

A

homologous pairing

55
Q

What happens in the pachynema stage of prophase I?

A

stage 3: pairing and synapsis complete, formation of tetrads, starting of crossing over

56
Q

What are tetrads?

A

A group of sister chromatids (2) and non-sister chromatids (2)

57
Q

What is crossing over?

A

the genetic exchange between two non-sister chromatids

58
Q

What happens in the diplonema stage of prophase I?

A

stage 4: crossing over is complete, non-sister chromatids start to separate

59
Q

What is the biological importance of crossing over?

A

generates new combinations of parental genetic material
source of genetic variability
corrects mutations

60
Q

What is a chiasmata?

A

reflects the site of recombination (cross overs)

61
Q

What happens in the diakinesis stage of prophase I?

A

stage 5: tetrad appearance fades, chiasma becomes less visible/moves toward end of tetrad, nucleolus and nuclear envelope dissolve

62
Q

How many cell divisions happen after prophase I and what are they?

A

two:
1. metaphase I –> telophase I
2. metaphase II –> telophase II

63
Q

What happens during metaphase I?

A

each tetrad has 2 centromeres, terminal chiasmata hold non-sister chromatids together, orientation on metaphase plate random

64
Q

What happens during anaphase I?

A

separation of homologous chromosomes (dyads are mixture of parental genomes)

65
Q

What happens during telophase I?

A

cytokinesis and karyokinesis

66
Q

Is there an interphase phase in meiosis? If so, how is it different than that in mitosis?

A

Yes, there is NO DNA replication. Only for transcription and translation

67
Q

What happens during metaphase II –> telophase II?

A

Similar process to mitosis, results in 4 haploid gametes, each monad is a mixture of parental genomes

68
Q

To ensure proper segregation of homologs how many crossovers must occur during the first meiotic division?

A

At least one per meiotic chromosome pairs

69
Q

What does DSBs stand for?

A

meiotic DNA double-strand breaks

70
Q

Formation of crossovers is strictly dependent on what?

A

formation and subsequent repair of DSBs

71
Q

How are DSBs repaired?

A

homologous recombination

72
Q

What are DSBs produced by?

A

topoisomerase related protein SPO-11

73
Q

On average, how many meiotic DSBs are produced on a single chromosome pair?

A

2 (bivalent)

74
Q

Repairs of DSBs result in either…

A

cross overs (Holliday junction intermediate) or non-cross overs

75
Q

What protein binds to recombination hotspots?

A

PRMD9 (zing finger protein)

76
Q

How does frequency of recombination differ between males and females?

A

females have a higher rate of recombination than males

77
Q

What causes a higher rate of recombination?

A

more short chromosomes, at distal end of chromosomes, GC rich DNA and genes

78
Q

The frequency of recombination is regulated by what?

A

chromatin structure (open/close) and chromatin marks (histone methylation)

79
Q

What are hotspots?

A

short regions distributed all over the genome where recombination can occur

80
Q

Where is the highest recombination rate known to be?

A

Major Histocompatibility Complex (MHC)
The Pseudo Autosomal Region (PAR)

81
Q

What are cold spots?

A

Place where recombination does not occur

82
Q

What is the best known cold spot?

A

centromeres

83
Q

List the steps of spermatogenesis (in order) and whether the step is diploid or haploid.

A

spermatogonium (2n)
primary spermatocyte (2n)
secondary spermatocyte (n)
spermatids (n)
spermatozoa (n)

84
Q

List the steps of oogenesis (in order) and whether the step is diploid or haploid.

A

primordial germ cells
oogonium (2n)
primary oocyte (2n)
secondary oocyte/first polar body (n)
ootid/secondary polar body (n)
ovum (n)

85
Q

Why is there an unequal division of cytoplasm between an oocyte and the first polar body?

A

Necessary for embryonic development

86
Q

What happens to the number of oocytes as a female matures?

A

They decrease

87
Q

When does meiosis II take place in females?

A

Only after fertilization

88
Q

What is dictyate?

A

When oogenesis stops at diplonema

89
Q

When does oogenesis resume and what is completed?

A

resumes in puberty and completes the first meiotic division forming secondary oocyte and first polar body

90
Q

Why is meiosis important?

A

re-shuffles genetic material and enhances genetic variation

Biomedical Genetics (6 decks)

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