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mitosis Flashcards

1
Q

Growth

A

the permanent increase in size / number of cells

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2
Q

2 types of cells

A

somatic cells and germ cells (gametes)

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3
Q

somatic cells

A

all body cells that undergoes mitosis / karyokinesis, followed by cytokinesis

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4
Q

gametes

A

produced by gonads, made through the process of meiosis, followed by cytokinesis

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5
Q

Nucleus

A

 6 μm
 controls the activity of cells
 carries DNA, which contain many genes which code for
polypeptide

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6
Q

Chromosome

A

chromatin – DNA

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7
Q

Gene

A

a functional segment of DNA that codes for a polypeptide

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8
Q

During growth of multicellular organisms, the

A

nucleus divides before the cells divide so that each new cell contains an identical nucleus.

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9
Q

why is cell divison important

A

This is important because the nucleus controls the cell’s activities. It does this because it contains the genetic material, DNA, which acts as a set of instructions, or code , for life

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10
Q

All living organisms

A

grow and reproduce – all living organisms are made up of cells – so cells need to grow and reproduce

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11
Q

Cell division

A

dividing and passing on genes to their
‘daughter cells ’ - a precisely controlled process

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12
Q

Just before a eukaryotic cells divides

A

, a number of thread-like structures called chromosomes gradually become visible in the nucleus

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13
Q

how do chromosomes become easily visible

A

intensely stained with particular stains

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14
Q

The number of chromosome is

A

characteristic of a species

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15
Q

Just before nuclear division, chromosomes are seen as

A

2 sister chromatids.

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16
Q

2 sister chromatids are held by a

A

the narrow region called a
‘centromere’

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17
Q
A
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18
Q

The centromere can be found anywhere

A

along the length of the chromosome, but the position is characteristic for a particular chromosome.

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19
Q
A

telocentric

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20
Q
A

arcocentric

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21
Q
A

submetacentric

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22
Q
A

metacentric

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23
Q

histones

A

DNA that are negatively charged and acidic, associates with basic proteins

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24
Q

DNA + HISTONE OCTAMER =

A

1 NUCLEOSOME

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25
Q

The DNA is wrapped around the

A

outside of the cylinder, making 1⅔ turns (equivalent to 147
base pairs) before linking to the next nucleosome

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26
Q

Nucleosomes fold up to

A

make chromatin

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27
Q

Chromatin condenses to form

A

chromosomes or chromatids

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28
Q

Histone proteins

A

H1, H2A, H2B, H3, H4

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29
Q

core of nucleosome

A

4 of these proteins [H2A, H2B, H3, H4] occur in pairs to produce histone octamer

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30
Q

Histones help in

A

compact packaging of DNA -
DNA in one cell is 1.8 m long and is fitted
into a nucleus which is 6 μm in diameter

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31
Q

Histones are absent in

A

prokaryotes

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32
Q

H1 histone

A

known as the linker histone – locks the DNA to the histone octamer

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33
Q
A

chromatin

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34
Q
A

1 nucleosome

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35
Q

Each chromosome has a constriction point
called the centromere

A

which divides the chromosome into two sections, or “arms.” The short arm of the chromosome is labeled the “p arm.” The long arm of the chromosome is labeled the “q arm.”

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36
Q

A normal cell -

A

46 DNA strands

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37
Q

Just before karyokinesis

A

46 DNA makes one copy of itself – ‘DNA replication’ – to form 92
DNA

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38
Q

92 DNA’s condenses to form

A

92 chromatids

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39
Q

2 chromatids together makes

A

one chromosome

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40
Q
A
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41
Q

EUCHROMATIN

A

-The packing is not tight.
-Euchromatin are loosely coiled regions.
-Euchromatin contains less DNA.
-The genes in the euchromatin are active.

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42
Q

HETEROCHROMATIN

A

-Heterochromatins have tighter DNA packaging.
-Heterochromatins are compactly coiled
regions.
-Heterochromatin contains more DNA
-The genes in the heterochromatin are mostly
inactive.

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43
Q

The DNA is wound

A

around the outside of protein molecules.

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44
Q

chromatin

A

The combination of DNA and proteins

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45
Q

nucleosome shape

A

cylindrical in shape, about 11 nm wide by 6
nm long

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46
Q

nucleosome is made up of

A

eight histone molecules.

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47
Q
A
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48
Q

The cell cycle

A

is the regular sequence of events that takes place between one cell division and the next

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49
Q

3 phases in cell cycle

A
  • interphase[G1, S, G2],
  • nuclear division, and
  • cell division
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50
Q

INTERPHASE

A

The cell grows to its normal size and carries out its normal functions until it receives a signal to divide again

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51
Q

G1 phase [GAP 1 / GROWTH PHASE 1]

A
  • the gap in between cell division and S phase/synthesis phase;
  • the cell undergoes maximum growth;
  • Cell is metabolically active
  • Duplication of organelles
  • Synthesis proteins, enzymes and nutrients required for DNA replication
  • cells make the RNA, enzymes, and other proteins needed for growth and DNA replication;
  • monitors environment – if suitable it moves to the S phase;
  • Check point – checks if enough resources are available for the S phase;
  • Processes like transcription, translation, protein synthesis, organelle synthesis, etc, occur
    in this phase;
  • High metabolic rate
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52
Q

G0 phase

A

inactive phase; neurons and cardiac muscles enters G0 phase; Some cells in the
adult animals do not appear to exhibit division (e.g., heart cells) and many other cells divide
only occasionally, as needed to replace cells that have been lost because of injury or cell
death. These cells that do not divide further exit G1 phase to enter an inactive stage called
the quiescent stage (G0 ) of the cell cycle. Cells in this stage remain metabolically active but
no longer proliferate unless called on to do so depending on the requirement of the organism

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53
Q

S phase [synthesis phase]:

A

*DNA replication takes place;
*histones are made and DNA gets wrapped around the histone proteins; checkpoint – checks if DNA replication is correct, if wrong the cell getsdestroyed

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54
Q

G2 phase:

A
  • the gap after the S phase and before cell division;
  • a short growth phase;
  • energy reserve increases;
  • centrioles replicate
  • check point - the cell continues to grow and the new DNA that was made during the S phase is checked and any errors are repaired;
  • preparations for mitosis start e.g. sharp increase in the number of tubulin molecules to make microtubules
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55
Q

Checkpoints in the cell cycle of mammals prevent

A

the cycle from continuing when
mistakes are made or DNA is damaged

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56
Q
A
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57
Q

MITOSIS

A

Mitosis is the nuclear division that
produces two genetically identical
daughter nuclei, each containing the
same number of chromosomes as the
parent nucleus.

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58
Q
A

interphase

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59
Q
A

prophase

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60
Q
A

metaphase

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61
Q
A

anaphase

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62
Q
A

telophase

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63
Q

SIGNIFICANCE OF MITOSIS

A

1.Repair of tissues
2.Replacement
3.Regeneration
4.Asexual reproduction
5.Growth
6.Maintaining chromosome number

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64
Q

M PHASE /
MITOTIC DIVISION

A
  • starts after interphase[G1, S, G2];
  • referred to as M phase
  • growth stops temporarily;
  • to create two genetically identical cells.
  • a precisely controlled process
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65
Q

after mitosis, in animal cells

A

the cytoplasm constricts – cytokinesis

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66
Q

in plant cells, a new cell wall is formed in

A

between the 2 nuclei

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67
Q

the length of the cell cycle is very

A

variable, depending on environmental
conditions and cell type

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68
Q

root tip cells divide every

A

20 hours

69
Q

epithelial cells in the human intestine divide every

A

10 hours

70
Q

PROPHASE

A
  • nucleolus disappears
  • nuclear membrane disassembles
  • chromatin condenses to form chromosomes
  • chromosomes become short and thick
  • 2 chromatids joined by centromere
  • centrioles start moving to opposite poles
  • spindle fibre begins to form
71
Q

METAPHASE

A
  • chromosomes line up at the equator
  • chromosomes are at their thickest level
  • spindle fibres from centrioles attached to the centromere / kinetochore
  • spindle at its maximum length
  • distance between chromatid is zero
72
Q

ANAPHASE

A
  • sister chromatids starts getting separated
  • chromosomes seen in ‘v’ shape
  • spindle fibre contracts to pull the chromatids towards the opposite poles
  • distance between sister chromatids increases
  • Spindle length decreases
73
Q

TELOPHASE

A
  • chromatids reached opposite poles
  • nucleolus reappears
  • Nuclear membrane reassembles / reforms
  • chromatids gets loosely arranged to form chromatin
74
Q
A

prophase

75
Q
A

metaphase

76
Q
A

anaphase

77
Q
A

telophase

78
Q

mitotic index=

A

number of cells in mitosis/total number of cells

79
Q

CANCER

A
  • Uncontrolled cell division caused due to mutation
  • short interphase
80
Q

Cancers are thought to start when

A

changes occur in the genes that control cell division

81
Q

Genes involved in cell division in cancer

A
  1. Protooncogenes
  2. Tumour suppressor gene
82
Q

Protooncogenes

A

It stimulates normal cell division. When mutated, it forms oncogenes which result in abnormal cell mass / tumour

83
Q

Tumour suppressor gene

A

– prevent tumour formation. Due to mutation, action
of this gene is switched off.
* not all tumours are cancerous

84
Q

Types of tumour

A

1)Benign tumours
2)Malignant tumours

85
Q

Benign tumours

A

Some tumours do not spread from their site of origin, and are known as benign tumours; warts are a good example.

86
Q

Malignant tumours

A

tumours that spread through the body, invade other tissues and destroy them are known as malignant tumours. Malignant tumours interfere with the normal functioning of the area where they have started to grow. They may block the intestines, lungs or blood vessels.

87
Q

Metastasis

A

Cells can break off and spread through the blood and lymphatic system to other parts of the body to form secondary growths. The spread of cancers in this way is called metastasis. It is the most dangerous characteristic of cancer, since it can be very hard to find secondary cancers and remove them

88
Q

Contact inhibition

A

normal cells stop dividing when they come in contact
with other cells. This property is lost during cancer.

89
Q

Angiogenesis

A

Physiological process by which a new blood vessel is formed
from the preexisting ones to provide nutrients to the tumor cells.
Tumor cells secrete signals that help in angiogenesis

90
Q

factors that can affect cancer

A

X ray, gamma rays, UV rays, food preservatives, flavouring, colouring, tar in
smoke

91
Q

process of a mutation causing cancer

A
92
Q

centromere is visible as

A

a constriction in the chromosome

93
Q

centromere is the site of

A

attachement of spindle microtubules for the seperation of chromatids during mitosis

94
Q

each metaphase chromosome contains

A

2 kinetochores at its centromere, one one each chromatid

95
Q

kinetochores made from

A

protein molecules which bind specifically to the DNA in the centromere and also bind to microtubules

96
Q

spindle fibres

A

bundles of microtubules extend from the kinetochores to the poles of the spindle during mitosis

97
Q

formation of kinetochores begins before

A

nuclear duivision starts ( during the S phase of the cell cycle )

98
Q

the microtubules attached to a given kinetochores pull the

A

kinetochores, with the rest of its chromatid dragging behind, towards the pole, this is done by shortening of the microtubules, both from the pole end and deom the kinetochores end

99
Q

poles of the spindle are

A

where the centrosome are located , one at each pole

100
Q

centrosome

A

it is an organelle found in aminal cells that acts as the microtubule organizing centre (MTOC) for the formation of spindle

101
Q

each centrosome consits of a pair of

A

centrioles surrounded by a large number of proteins, it is these proteins that control production of the microtubule not the centrioles

102
Q

plant mitosis occurs without

A

centrosomes

103
Q

the significance of mitosis in cell replacementr and tissue repair by stem cells

A
  • a stem cell is a cell that can divide an unlimited number of times (by mitosis_
    when it givides each new cell has the potential to remain a stem cell or to develop (differentiate) into a specialized cell such as a blood cell or muscle cell
104
Q

potency

A

extent of the power of a stem cell to produce different cell types is variable and is reffered to as its potency

105
Q

stem cells that can produce any

A

type of cell are described as totipotent

106
Q

totipotent example

A

the zygot fromed by the fusion of a sperm with an egg at fertilization is totipotent , as are the cells up to the 16-cell stage of development in humans

107
Q

embryonic stem cells

A

are pluripotent, after fertilization, some cells become specialized to form placenta while others loose this ability but can form all the cells that will lead to the development of the embryo and later the adult

108
Q

as tissues, organs and systems develop

A

cells become more and more spexialized

109
Q

number of different cell types-

A

more than 200 different cell types

110
Q

multipotent

A

the more specialized cells become to particular role, the more they loose the ability to divide until , in adult, most cells do not divide

111
Q

for growth and repair, it is essential that small populations of stem cells remain

A

which can produce new cells

112
Q

adult stem cells have already

A

lost some of the potency associated with embryonic stem cells and are no longer pluripotent. they are only able to produce a few types of cell and mayb be describe as multipotent

113
Q

multipotent example

A

stem cells found in bone marrow, they can replicate any number of times, but can produce only blood cells. mature blood cells have a relatively short lifespan, so th existence of these stem cells is essential

114
Q

location of stem cells in adult

A

in the adult, stem cells are found throughout the body- for example in the bond marrow, skin, gut, heart and brain

115
Q

medical application of stem cells

A

stem cell therapy is the introduction of new adult stem cells into damaged tissue to treat disease or injury, bone marrow transplantation is the only form of this therapy that has progressed beyond the experimental stage into routine medical practice, but in the future it is hoped to be able to treat conditions like diabetes, muscle and nerve damage, and brain disorders such as parkingsons and huntignsons disease
experiments with growing new tissues or even organs from isolated stem cells in the labaroty have also been conducted

116
Q

in which process does mitosis not have an important role in living
things?

A

growth of cells
The growth of cells does not involve mitosis, whilst an increase in size of
living things would involve mitosis to produce more cells.
^ig “of cells” is the wrong term here (?

117
Q

rowth of single celled organisms is not a result of

A

mitosis.

118
Q
A
119
Q

during which process does mitosis occur?

A

production of cancerous tissue in alveoli
bio post pp notes 17
production of antibodies from memory cells is NOT mitosis (its a sort of
secretion if u think ab it)

120
Q

exposure to which can increase risk of cancer

A
  1. uv light
  2. viruses
  3. x rays / ionising radiation in general
    co has no effect
121
Q

which changes in a group of mammalian cells, dividing by mitosis, would
be necessary for the formation of a tumour?

A
  1. mitosis is no longer inhibited by cell to cell contact
  2. cells acquire the ability to migrate and set up new colonies
  3. cells become able to divide indefinitely
    1 and 3 = answer boom
122
Q

littall bit ab structure of dna

A

very long dna molecule of each chromatid is coiled and held together by
proteins called histone

123
Q

in those confusing diagrams where you can’t tell if its cytokinensis or
interphase, look at the size of the cell! (

A

A significant number of candidates did not take into account the size of
the cell labelled 4. Cell 4 and the cell to the right of it have been
produced recently as a result of cytokinesis. Cell 3 is at least 3 times
larger as a result of the G phase in interphase allowing the cell to
proceed to prophase.
ans B

124
Q

cells which transcribe telomerase:

A

stem cells, memory cells, and tumour
cells [during mitotic cell cycle, the length of their telomeres remains the
same]

125
Q

position of chromosomes on equator of spindle does not effect

A

maintenance of genetic consititution of dna (cuz like they re all on the
equator)

126
Q

ength of telomeres stays the same during mitosis of a

A

cancer cell

127
Q

telomeres prevent introns and exons being lost from g

A

genes during cell
division

128
Q

during telophase, there’s 2 telomeres per

A

chromosome (visualize it)

129
Q

lets say chromatids are prevented from separating

A

the cell reaches metaphase but DOES not complete it because chromatids start to be
pulled apart during metaphase

130
Q

cancer cells/tumour cells take less time in

A

interphase (ONLY)

131
Q

cytoplasm starts to divide

A

immediately after telophase (cytokinensis
follows)

132
Q

lack of formation of spindle fibres affects

A

prophase first

133
Q

growth of single-celled organisms not due to

A

mitosis! [its cell growth
only

134
Q

during cytokinensis, 2 molecules of dna can be

A

found

135
Q

organells duplicate during

A

g1 and nuclear envelope reforms during telophase

136
Q

during cytokinensis =

A

cell structures are shared between two cells

137
Q

dna content halves during

A

telophase (comes in those graph qs)

138
Q

mitosis produces

A

2 daughter cells

139
Q

plant cells don’t have

A

centriole

140
Q

omologous chromosomes don’t pair during

A

mitosis (they pair during
meiosis only)

141
Q

“forms cells of equal size to

A

parent cell” - not a feature of nuclear
division by mitosis

142
Q

chromosomes uncoiling happens during

A

telophase

143
Q

p53 is a

A

tumour suppressive gene (also if u want cancer —> original
genes shudnt be present, only mutated genes)

144
Q

uv and ionising can cause

A

power

145
Q

protein synthesis (translation and all) is a part of the

A

mitotic cell cycle
[happens during interphase in g1]

146
Q

prokaryotes do not have

A

telomeres

147
Q

during prophase chromosome has

A

4 dna strands (before replication it
was 2 strands

148
Q

clonal selection does not involve

A

mitosis (only clonal expansion)

149
Q

if thickening of chromosomes is increased,

A

ts probably bcz histone got
replaced

150
Q

mitosis helps in tissue repair NOT

A

cell repair

151
Q

organelle replication/centriole replication occurs during

A

s phase

152
Q

Whilst the role of histones is relatively new to the syllabus candidates
should know that during prophase e

A

each chromosome consists of two
chromatids. (im guessing that when they tell u the stage of mitosis and
give smthn related to structure, just go w ur basic knowledge) - dont try
to eliminate options, j pick the most relevant one

153
Q

telomeres prevent loss of genes during

A

dna replication (which happens
during s phase of interphase)

154
Q

Prophase and metaphase

A
  1. chromatids / chromosomes / chromatin, condense / become shorter / become thicker / coil / supercoil / AW ; A ‘become (more) visible’
  2. centrioles, move to / reach, opposite poles ; R ends
  3. nucleolus disappears ;
  4. spindle is formed ; A ‘more developed’ A description in terms of spindle fibres
  5. ref to assembly of microtubules ; A ‘makes’ microtubules R 9+2
  6. nuclear envelope, disintegrates / breaks down / destroyed / AW ; A membrane
  7. chromosomes, move to / at, equatorial plate / equator / metaphase plate / AW ; ignore middle / centre
  8. centromeres attach to, spindle / fibres ;
  9. ref to random arrangement of chromosomes ; A ‘not in pairs’ R scattered
155
Q

Features characteristic of metaphase

A

chromosomes / (sister) chromatids, line up at the, equator / equatorial plate / metaphase
plate ; A move to I middle / centre
centromeres attached to, spindle / spindle fibres ;
A (spindle) microtubules A kinetochore
centrioles, reach / located at / AW, poles ; R ends
ref. spindle fully formed ; A spindle fibres extend from poles / AW
R ref. to nuclear envelope absent (in anaphase also)

156
Q

Describe the cell during prophase

A

Chromosomes have condenses/coiled up so they are more visible
Two sister chromatids held together by centromere
Each chromatid has 1 DNA molecule
DNA is associated with histone proteins

157
Q

Cytokinesis:(plant)

A

Cell plate forms / cell wall/cellulose laid own or A formed (only for plants)
Cytoplasm divides into two
AVP ; detail of cell plate formation e.g. ref. to vesicles transported to equator / involvement of cytoskeletal structures idea that organelles shared out
Cell plate becomes middle lamela
Animal cells
1.The circular protein fibres in cell surface membrane start to constrict towards the center at metaphase plate
2.By rearrangement of phospholipid bilayer cells will be divided in 2

158
Q

Importance of mitosis:suggest and explain

A

replacement of cells ;
repair of tissue ; R repair of cells
growth / increase in cell numbers ;
asexual reproduction / vegetative propagation ; R cloning
maintains / same, number of chromosomes ; A two sets of chromosomes / diploid / 2n
genetically identical to parents ;
A produces daughter cells that are genetically identical A ref. clone(s)
ref to rejection / self vs non-self ;

159
Q

ref to rejection / self vs non-self ;

A
160
Q

Outline role of microtubules in mitosis

A

Forms part of spindle fibre
Attaches to centromere/chromosome
Moves sister chromatids to opposite poles

161
Q

Outline the changes that occur as a stem cell transforms into a mature RBC

A

Stem cell divides rapidly
synthesises/produces/makes haemoglobin
synthesises/produces/makes carbonic anhydrase
Loss of nucleus
Loss of organelles eg. ribosome, mitochondria
Becomes biconcave

162
Q

Suggest importance of mitotic cell cycle timing and control

A

Coordination of growth
Minimises exposure to mutation
Prevents tumour formation
Which would spread to other tissues
Allows producing cell only when required

163
Q

Outline how mutations can cause healthy cells to become tumour cells:

A

idea that mutation occurs for a gene controlling cell division ;
detail ; e.g. proto-oncogene to oncogene
tumour suppressor gene switched off ;
ref. to disruption of cell cycle / shortened interphase ;
(results in) uncontrolled cell division ; I uncontrolled growth
other detail of result of mutation ; e.g. divide indefinitely / no programmed cell death do not respond to signals to stop dividing loss of, specialisation / function

164
Q

Role of centrioles in animal cells

A

Important in mitosis
Replicated before cell division
Organises microtubules
Moves to opposite poles
Organises microtubules to form spindle

165
Q

Structure of chromatids in metaphase:

A

two chromatids ;
identical / sister, chromatids ;
joined by a centromere ; A kinetochore
one from
(reach chromatid) DNA complexed with protein
histone proteins / histones ;
telomeres at end of chromatids

166
Q

State two differences between the chromosome at metaphase and the chromosome at late anapha

A

two chromatids versus, one chromatid / one daughter chromosome ;
sister chromatids joined at centromere versus chromatids separated
distance between sister chromatids zero versus increasing distance between chromatids
share a centromere versus do not share a centromere / centromere divides
two DNA molecules versus one DNA molecule ;
at, equator / metaphase plate versus towards / at, poles ; R centre R ends
linear / straight versus V shape / AW

167
Q

Outline function of telomeres:

A

I shortening of chromosomes
permit continued replication ;
prevent loss of genes ; I prevents gene damage A genetic / coded, information A protein coding regions of DNA
protect ends of chromosomes from being, degraded / AW ;
AVP ; e.g. prevents ends of chromosomes from being attached to each other not mistaken for a break in DNA that needs repairing

168
Q

Suggest a reason why daughter cells are not identical immediately after cytokinesis

A

unequal sharing out of, cytoplasm / organelles / named organelles, (at cytokinesis) ;
A uneven sizes

9700 (13 decks)

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