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Biology of Cells 2 > Chromosomes and Cell Division > Flashcards

Chromosomes and Cell Division Flashcards

1
Q

Chromosomes and Cell Division

Primary function of genetic material

A

Store information

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2
Q

Chromosomes and Cell Division

Histone

A

Protein

DNA wrapped around it

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3
Q

Chromosomes and Cell Division

Why is the histone attracted to the DNA

A

DNA has a negative charge

Histone has a positive charge

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4
Q

Chromosomes and Cell Division

By how much does DNA wrapping around histone shorten it?

A

Sevenfold

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5
Q

Chromosomes and Cell Division

Nucleosome

A

Repeating unit of DNA wrapped around an octamer of histone proteins

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6
Q

Chromosomes and Cell Division

How are nucleosomes organised?

A

Into an even more compact structure

30nm fibre

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7
Q

Chromosomes and Cell Division

Radial loop domains

A
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8
Q

Chromosomes and Cell Division

Two proposed models for structure of 30nm fibre

A

Three dimensional zig-zag model

Solenoid model

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9
Q

Chromosomes and Cell Division

Why are we unsure about the structure of the 30nm fibre?

A

DNA conformation may be altered when extracted from living cells

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10
Q

Chromosomes and Cell Division

Types of compaction of chromosomes

A

Heterochromatin

Euchromatin

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11
Q

Chromosomes and Cell Division

Heterochromatin

A

Transcriptionally inactive

Very compact

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12
Q

Chromosomes and Cell Division

Echaromatin

A

Less condensed than heterochromatin

Capable of gene transcription

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13
Q

Chromosomes and Cell Division

Which type of chromsome compaction is most common in non-dividing cells?

A

Euchromatin

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14
Q

Chromosomes and Cell Division

What happens to chromatin compaction during cell division?

A

All Euchromatin converted to heterochromatin

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15
Q

Chromosomes and Cell Division

Individual chromosomes are located in their….

A

Discrete, non-overlapping territory

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16
Q

Chromosomes and Cell Division

Chromosome compaction at metaphase

A

Radial loops remain anchored to scaffold formed from proteins in the nuclear matrix

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17
Q

Chromosomes and Cell Division

How many different chromosomes do humans have?

A

23

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18
Q

Chromosomes and Cell Division

How many chromosomes do humans have in total?

A

46

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19
Q

Chromosomes and Cell Division

Haploid cells

A

Only have one member of a chromosome pair

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20
Q

Chromosomes and Cell Division

Diploid cells

A

Have full set of chromosomes

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21
Q

Chromosomes and Cell Division

When a species is diploid, members of a pair of chromosomes are called….

A

Homologues

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22
Q

Chromosomes and Cell Division

Homologues

A
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23
Q

Chromosomes and Cell Division

Cell cycle (time taken)

A

G1 (11 hours)

S (8 hours)

G2 (4 hours)

M (1 hour)

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24
Q

Chromosomes and Cell Division

Cell cycle (shorthand and long)

A

First gap (G1)

DNA synthesis (S)

Second gap (G2)

Mitosis (M)

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25
Q

Chromosomes and Cell Division

Shortest stage in cell cycle

A

Mitosis

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26
Q

Chromosomes and Cell Division

Checkpoint proteins

A

Act as sensors to determine if the cell is in proper condition to divide

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27
Q

Chromosomes and Cell Division

What happens if checkpoint proteins find a problem

A

Cell division is delayed until it’s sorted or stopped entirely

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28
Q

Chromosomes and Cell Division

What does a loss of checkpoint function lead to

A

Mutation and cancer

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29
Q

Chromosomes and Cell Division

3 checkpoints in eukaryotic cell division

A

G1 checkpoint/restriction point

G2 checkpoint

Metaphase checkpoint

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30
Q

Chromosomes and Cell Division

S phase of DNA replication

A

DNA is replicated

Sister chromatids formed

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31
Q

Chromosomes and Cell Division

Sister chromatids

A

2 identical chromosomes copies

Tightly associated at centromere

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32
Q

Chromosomes and Cell Division

Centromere

A

Acts as an attachment site for kinetochore

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33
Q

Chromosomes and Cell Division

What is responsible for organising and sorting chromosomes during miosis?

A

Mitotic spindle

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34
Q

Chromosomes and Cell Division

What is the spindle formed from?

A

Microtubules

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35
Q

Chromosomes and Cell Division

What are microtubules formed from?

A

Tybulin proteins

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36
Q

Chromosomes and Cell Division

3 types of microtubules

A

Astral

Polar

Kinetichore

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37
Q

Chromosomes and Cell Division

Astral microtubules

A

Position spindle in the cell

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38
Q

Chromosomes and Cell Division

Polar microtubules

A

Seperate the 2 poles

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39
Q

Chromosomes and Cell Division

Kinetochore tubules

A

Attached to kinetochore of each chromosome

40
Q

Chromosomes and Cell Division

Stages of mitosis

A

Prophase

Metaphase

Anaphase

Teleophase

41
Q

Chromosomes and Cell Division

Stage of mitosis that don’t really need to know

A

Prometaphase

42
Q

Chromosomes and Cell Division

What happens before mitosis?

A

Interphase

43
Q

Chromosomes and Cell Division

Interphase

A

Phase where chromosomes are decondensed and found in nucleus

G1, S, G2 phases of cell cycle

44
Q

Chromosomes and Cell Division

What happens after mitosis?

A

Cytokinesis

45
Q

Chromosomes and Cell Division

Prophase

A

Chromasomes have already replicated to produce sister chromatids

Nuclear membrane dissociates into small vesicles

Chromatids condense

46
Q

Chromosomes and Cell Division

Prometaphase

A

Mitotic spindle is formed

Centrosomes move apart and set boundries of the two poles

Spindle fibres interact with sister chromatids

2 kinetichores on each pair of sister chromatids are attached to kinetochore microtubules from opposite poles

47
Q

Chromosomes and Cell Division

Metaphase

A

Pairs of sister chromatids are aligned along metaphase plate

Sister chromatids aligned into a single row

Cell is in metaphase when alignment complete

48
Q

Chromosomes and Cell Division

Metaphase plate

A

Plane halfway between the poles

49
Q

Chromosomes and Cell Division

Anaphase

A

Connections between the pairs of sister chromatids broken

Each individual chromosome is linked to one of the two poles by kinetichore microtubules

Kinetochore microtubules shorten, pulling chromomes toward the pole it’s attached to

The poles move further away from each other as overlapping polar microtubules lengthen and push against each other

50
Q

Chromosomes and Cell Division

Role of polar microtubules

A

They overlap and during anaphase lengthen and push against each other

This forces the two poles to move further apart

51
Q

Chromosomes and Cell Division

Which mircotubules pull the individual chromosomes to the poles?

A

Kinetochore microtubules

52
Q

Chromosomes and Cell Division

Telophase

A

Chromosomes have reached their respective poles

Chromosomes decondense

Nuclear membranes reform to produce two seperate nuclei

53
Q

Chromosomes and Cell Division

Cytokinesis

A

Stage where two nuclei are segregated into separate daughter cells

54
Q

Chromosomes and Cell Division

Cytokinesis in animals

A

Cleavage furrow constricts like a drawstring to separate the cells

55
Q

Chromosomes and Cell Division

Cytokinesis in plants

A

Cell plate forms a cell wall between the two daughter cells

56
Q

Chromosomes and Cell Division

Meiosis

A

Process by which haploid cells are produced from a cell that was originally diploid

57
Q

Chromosomes and Cell Division

How is meiosis different than mitosis?

A

Homologous pairs form a bivalent at prophase I

Crossing over between homologous chromosome pairs

58
Q

Chromosomes and Cell Division

What is the purpose of crossing over?

A

To form novel gene combinations

59
Q

Chromosomes and Cell Division

When does crossing over happen?

A

Prophase I

60
Q

Chromosomes and Cell Division

Crossing over (diagram)

61
Q

Chromosomes and Cell Division

Meiosis I diagram

62
Q

Chromosomes and Cell Division

Mieosis II diagram

63
Q

Chromosomes and Cell Division

What type of daughter cells does mitosis produce?

A

2 diploid cells

Identical

64
Q

Chromosomes and Cell Division

How many chromosomes in a human diploid cell?

A

46 (2 sets of 23)

65
Q

Chromosomes and Cell Division

How many chromosomes in a haploid human cell?

66
Q

Chromosomes and Cell Division

What type of daughter cells does meiosis produce?

A

4 haploid daughter cells

All slightly genetically different

67
Q

Chromosomes and Cell Division

Which form of cell division produces identical daughter cells?

68
Q

Chromosomes and Cell Division

What factors are chromosomes identified by?

A

Size

Location of centromere

Banding pattern

69
Q

Chromosomes and Cell Division

Metacentric

A

Centromere is in the middle of the chromosome

70
Q

Chromosomes and Cell Division

Submetacentric

A

Centromere is off centre

71
Q

Chromosomes and Cell Division

Acrocentric

A

Centromere is near the end

72
Q

Chromosomes and Cell Division

Telocentric

A

Centromere is at end

73
Q

Chromosomes and Cell Division

When centromere is in the middle of the chromosome

A

Metacentric

74
Q

Chromosomes and Cell Division

When centromere is off centre

A

Submetacentric

75
Q

Chromosomes and Cell Division

When the centromere is positioned near the end

A

Acrocentric

76
Q

Chromosomes and Cell Division

When the centromere is at the end

A

Telocentric

77
Q

Chromosomes and Cell Division

Deletion mutation

A

Segment missing/deleted

78
Q

Chromosomes and Cell Division

Duplication mutation

A

Section occurs 2 or more times in a row

79
Q

Chromosomes and Cell Division

Inversion mutation

A

Change in direction along a single chromosome

80
Q

Chromosomes and Cell Division

Translocation mutation

A

One segment becomes attached to another chromosome

Either simple or reciprocal

81
Q

Chromosomes and Cell Division

When the correct amount of chromosomes are present it is…

82
Q

Chromosomes and Cell Division

Polyploid

A

When 3 or more sets of chromosomes are present

83
Q

Chromosomes and Cell Division

Triploid

A

3 sets of chromosomes present

84
Q

Chromosomes and Cell Division

Tetraploid

A

4 sets of chromosomes present

85
Q

Chromosomes and Cell Division

Hexaploid

A

6 sets of chromosomes present

86
Q

Chromosomes and Cell Division

Trisomic

A

Normal 2 copies of a chromosome plus a 3rd

87
Q

Chromosomes and Cell Division

Aneuploidy

A

When total number of a particular chromosome isn’t correct

88
Q

Chromosomes and Cell Division

When missing one of a normal copies of a chromosome.

(when only one of a pair is present)

89
Q

Chromosomes and Cell Division

Non-disjunction

A

Chromosomes do not sort properly during cell division

90
Q

Chromosomes and Cell Division

Effects of non-disjuntion

A

If occurs during meiosis it can produce gametes with too many or too few chromosomes

91
Q

Chromosomes and Cell Division

In interspecies breeding when organisms have at least one set of chromosomes from 2 or more different species

92
Q

Chromosomes and Cell Division

In interspecies breeding, 2 or more complete sets of chromosomes from 2 or more different species

A

Allopolyploidy

93
Q

Chromosomes and Cell Division

In interspecies breeding when 2 complete sets of chromosomes from 2 different species are present, making a total of 4 sets

A

Allotetraploid

94
Q

Chromosomes and Cell Division

Organism that commonly exhibit polyploidy

95
Q

Chromosomes and Cell Division

Do animals usually tolerate deviations from diploidy?

A

No

Usually lethal for offspring

96
Q

Chromosomes and Cell Division

Synapsis

A

The process of forming a bivalent

Biology of Cells 2 (5 decks)

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