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Biology (Nora) > Cell division > Flashcards

Cell division Flashcards

1
Q

cells can only be formed from?

A

existing cells

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2
Q

when a new cell forms it goes through 3 stages before it can divide again. what are they?

A

synthesis of materials it will need
growth
reproduction to form new cells

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3
Q

the forming of new cells is called

A

cell continuity

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4
Q

cell continuity can be summarised in

A

the cell cycle

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5
Q

what does the cell cycle describe

A

interphase and mitosis

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6
Q

what is interphase

A

a cell’s state of non-division

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7
Q

what is a state of mitosis

A

a cell’s state of division

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8
Q

3 stages of the cell cycle

A

division of nucleus
division of cell
interphase

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9
Q

the long part of the cell cycle

A

interphase

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10
Q

the short parts of the cell cycle

A

division of nucleus

division of cell

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11
Q

what occurs in the division of nucleus stage

A

mitosis

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12
Q

what occurs in the division of cell stage

A

cytokinesis

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13
Q

where are chromosomes found?

A

in the nuclei of the cells

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14
Q

what are chromosomes made of

A

DNA and protein

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15
Q

what does DNA stand for?

A

deoxyribonucleic acid

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16
Q

in a cell that is not dividing the chromosomes are in what form?

A

in the form of chromatin

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17
Q

what does chromatin look like

A

long, thin threads

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18
Q

what happens to chromatin during cell division

A

it condenses to chromosomes

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19
Q

what do chromosomes look like in comparison to chromatin?

A

shorter, thicker and clearly visible

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20
Q

every organism has a distinct

A

number of chromosomes

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21
Q

most human cells have how many chromosomes

A

46

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22
Q

each chromosome contains what along its length

A

each chromosome contains many genes across its length

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23
Q

what is a gene?

A

a section of DNA that codes for a particular protein

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24
Q

how many genes on human chromosomes

A

over 30,000

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25
Q

2 things that genes control in humans

A

eye colour, blood groups etc

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26
Q

3 things that genes control in plants

A

height
flower colour
seed shape

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27
Q

Human genome project

A

the sequence of genes on human chromosomes has been mapped, this is the human genome project

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28
Q

how long has the human genome project taken?

A

10 years to complete it

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29
Q

genome

A

all the genes present in an organism

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30
Q

in most organisms chromosomes appear in

A

in pairs

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31
Q

how many pairs of chromosomes in humans

A

23

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32
Q

how many chromosomes in humans

A

46

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33
Q

diploid number of chromosomes represented as

A

2n

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34
Q

in humans, 2n =

A

46

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35
Q

diploid number

A

how many pairs of chromosomes an organism has

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36
Q

these pairs of chromosomes are called

A

homologous chromosomes

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37
Q

diploid cell

A

2 sets of chromosomes

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38
Q

haploid cells

A

cells that only have one set of chromosomes

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39
Q

2 cells in humans that are haploid cells

A

sperm cell

egg cell

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40
Q

haploid cells represented by the symbol

A

n

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41
Q

in humans n=

A

23

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42
Q

2 types of cell division

A

mitosis

meiosis

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43
Q

mitosis

A

when cells divide, one parent cell gives rise to 2 identical daughter cell

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44
Q

parent cell 2n=

A

4

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45
Q

daughter cells 2n =

A

4

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46
Q

body cells, every cell but reproductive cells

A

somatic cells

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47
Q

when does mitosis occur

A

in the growth and replacement of cells

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48
Q

somatic cells divide by

A

mitosis

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49
Q

2 examples of somatic cells

A

skin cells

liver cells

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50
Q

in plants mitosis occurs in?

A

meristematic cells

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51
Q

where are meristematic cells found?

A

in the root tip and shoot tip

52
Q

meristem

A

a zone of active cell division

53
Q

reproduction by mitosis

A

some simple organisms reproduce asexually by mitosis

54
Q

2 examples of organisms that can reproduce by mitosis

A

yeast and amoeba

55
Q

preparation for mitosis down as

A

interphase

56
Q

interphase

A

the phase between cell divisions during which the cell prepares for the next division

57
Q

what happens during interphase

A

DNA replicates

58
Q

during interphase each chromosome consists of

A

2 identical strands joined together at a point

59
Q

2 identical strands joined together at a point

A

chromatids

60
Q

centromere

A

where the 2 chromatids are joined together

61
Q

what happens when DNA replicates itself

A

makes an exact copy of itself

62
Q

why is the replication of DNA very important?

A

it allows genetic information to be passed fro one generation to the next

63
Q

what also replicates

A

cell organelles e.g. mitochondria

64
Q

why do cell organelles replicate?

A

to build up the cells energy store

65
Q

what occurs when cell organelles replicate

A

protein synthesis occurs

66
Q

4 stages of mitosis

A

prophase
metaphase
anaphase
telophase

67
Q

length of prophase

A

usually the longest phase

68
Q

what happens to chromatin during prophase

A

shortens to form chromosomes

69
Q

when does DNA replicate

A

prior to prophase

70
Q

what happens to the nuclear membrane during prophase

A

it disappears

71
Q

what starts to form in prophase

A

spindle fibres start to form

72
Q

what forms the spindle fibres

A

centrioles

73
Q

what structure do the spindle fibres form

A

the spindle

74
Q

what happens to the nucleolus during prophase?

A

it disappears

75
Q

what is the function of the nucleolus

A

makes ribosomes

76
Q

2 events of metaphase

A
  1. the pairs of chromatids become attached to the spindle fibres at their centromeres
  2. the pairs of chromatids line up across the middle of the spindle
77
Q

other name for middle of the spindle

A

equator of the spindle

78
Q

length of anaphase

A

this is a rapid phase

79
Q

events of anaphase

A

the centromeres split into 2 and the spindle fibres contract and pull the chromatids to opposite ends of the cell. they are now chromosomes

80
Q

what happens to chromosomes in telophase

A

when they reach the poles (ends) of the cell the chromosomes uncoil and become chromatin threads

81
Q

what forms arounds the chromatin in telophase

A

new nuclear membranes

82
Q

what happens to the nuclei in telophase

A

they reappear

83
Q

cytokinesis

A

the division of the cell immediately after mitosis

84
Q

what happens in animal cells during cytokinesis

A

a cleavage furrow appears which becomes deeper until it eventually divides the cytoplasm in 2

85
Q

what happens in plant cells during cytokinesis

A

a cell plate is formed between the two new nuclei

86
Q

cell wall formation during cytokinesis

A

a new cell wall forms on either side of the cell plate

87
Q

what happens to the cell plate then during cytokinesis

A

becomes the middle lamella

88
Q

function of middle lamella

A

cements the cells together

89
Q

chromosomes in daughter cells

A

identical to each other and parent cells

90
Q

cell resulting from mitosis have

A

identical genes

91
Q

cells resulting from mitosis are called

A

clones

92
Q

cancer

A

the uncontrolled division of cells (mitosis), producing abnormalities that are passed on to daughter cells

93
Q

deaths in ireland from cancer

A

1 in 4 deaths

94
Q

uncontrolled cell division produces

A

a mass of cells called a tumour

95
Q

benign tumours

A

not life threatening

do not invade other tissues

96
Q

example of a benign tumour

A

warts

97
Q

malignant tumours

A

invade other tissues and may be life threatening

98
Q

what causes cancer

A

when normal genes are changed into cancer causing genes called oncogenes

99
Q

cancer causing agents

A

carcinogens

100
Q

what are responsible for bringing about changes to genes to become oncogenes

A

carcinogens

101
Q

3 examples of carcinogens

A

UV radiation, cigarette smoke, some viruses

102
Q

what do carcinogens do

A

they cause changes in the DNA (mutations) which can cause cancer

103
Q

can cancers be cured

A

most cancers can be cured if they are caught and treated early

104
Q

3 treatments for cancer

A

surgery to remove tumour
radiation to burn out the tumour
chemotherapy to slow down mitosis

105
Q

4 ways to reduce the risk of cancer

A

do not smoke
eat a healthy diet
avoid sunburn
self examination for lumps on breasts/testes

106
Q

meiosis

A

a form of cell division involving a reduction from the diploid number of chromosomes to the haploid number

107
Q

meiosis is often called

A

a reduction division

108
Q

why is meiosis often called a reduction division

A

because the number of chromosomes is halved

109
Q

in meiosis parent cell

A

2n=4

110
Q

in meiosis 4 daughter cells

A

n=2 and non identical

111
Q

how does meiosis occur in animals

A

in the formation of gametes

112
Q

gamete

A

a haploid sex cell capable of fusion with another sex cell

113
Q

2 gametes

A

sperm cell

egg cell

114
Q

gametes formed by

A

meiosis

115
Q

gametes formed by meiosis and are therefore

A

haploid

116
Q

when is the diploid number of chromosomes restored in gametes

A

when fusion of gametes occurs during fertilisation

117
Q

meiosis leads to

A

genetic variation in daughter cells

118
Q

how many new cells (nuclei) formed in mitosis

A

2

119
Q

how many new cells (nuclei) formed in meiosis

A

4

120
Q

chromosome number in mitosis

A

stays the same

121
Q

chromosome number in meiosis

A

is halved

122
Q

daughter cells in mitosis

A

genetically identical to each other and to parent cell

123
Q

daughter cells in meiosis

A

genetically different to each other and to parent cell

124
Q

mitosis occurs in

A

haploid and diploid cels

125
Q

meiosis occurs in

A

diploid cells only

Biology (Nora) (18 decks)

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