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Biology Module 2 > 6. Cell Division > Flashcards

6. Cell Division Flashcards

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1
Q

Stages of cell cycle

A

interphase
onuclear division (mitosis)
ocell division (cytokinesis)

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2
Q

First phase

A

Interphase

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3
Q

What make up interphase

A

0G1 phase oS phase
0G2 phase

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4
Q

What happens in G1

A

cell grows in size.
DNA transcription happens.
Organelles are duplicated.
Protein synthesis occurs to make all enzymes and proteins needed for future stages.

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5
Q

What happens in synthesis phase

A

synthesising DNA. replicate dna. All the chromosomes turn into x shape because they’re duplicated = sister chromatids.

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6
Q

When do chromosomes look like x’s

A

When they’re ready to divide

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7
Q

Shortest phase during interphase and why

A

S phase because dna replication increases chance of mutation because the dna is exposed

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8
Q

What happens once a cell goes through s phase

A

It’s fully committed to cell division and it must occur

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9
Q

What happens in G2

A

Cell continues to grow

proteins synthesis happens for the proteins and enzymes which will be needed in the m phase.

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10
Q

Roles of mitosis

A

Growth and repair of tissues
Asexual reproduction
Production of new stem cells

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11
Q

Outline metaphase

A
  • chromosomes align on equator
  • chromatids either side of equator
  • spindle fibres attach to chromosomes at centromere
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12
Q

Outline prophase

A
  • chromosomes condense
  • chromosomes have become visible
  • nuclear envelope breaks down
  • spindle fibres start forming
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13
Q

Outline telophase

A
  • nucleolus becomes visible + organelles distribute
    • nuclear envelope forms around the new sets of chromosomes
  • Chromosomes uncoil
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14
Q

Outline anaphase

A
  • spindle fibres contract
  • chromatids separate and get pulled to opposite poles
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15
Q

How does sexual reproduction lead to genetic variation in offspring

A
  • genetic variation in variety of alleles
  • offspring have alleles from more than one parent
  • random fertilisation
  • crossing over in prophase one = alleles swapped between non sister chromatids = base sequence of chromosomes altered
  • independent assortment in metaphase 1 and 2
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16
Q

Why does sexual reproduction. Usually occur in winter

A
  • unfavourable conditions mean all offspring might die if asexual
  • this way some may survive as they might have useful alleles
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17
Q

Where does cell growth stop

A

Mitosis

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18
Q

What is cytokinesis

A

when the cytoplasm divides into 2 to create 2 identical daughter cells.

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19
Q

How is the cell cycle regulated

A

Checkpoints = • Specific proof-reading enzymes + repair enzymes are involved in this checking process

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20
Q

G0 phase

A

optional resting phase. This is usually for cells that don’t want to replicate, they just stay in G0. Or if they’ve gone through G1 and don’t want to divide they just stay in G0. This is also a phase where cells can become differentiated.

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21
Q

Checkpoints

A

where checks are happening to the dna to make sure everything is okay. Checks for any damage to the dna or mutations.

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22
Q

What is the purpose of checkpoints

A

to prevent formation of tumours = cancer

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23
Q

What happens if damage is found at a checkpoint

A

either repaired or the cell stops going through the cell cycle and apoptosis happens which is when the cell is killed.

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24
Q

P53 gene

A

gene that suppresses tumours by controlling the checkpoints.

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25
Q

How many checkpoints

A

4

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26
Q

G1 phase checkpoint

A

chromosomes are checked for damage.

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27
Q

S phase checkpoint

A

chromosomes are checked to ensure they have been replicated.

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28
Q

G2 phase checkpoint

A

an additional check for DNA damage occurs after the DNA has been replicated.

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29
Q

Metaphase checkpoint

A

final check determines whether the chromosomes are correctly attached to the spindle fires prior to anaphase

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30
Q

Where are the main checkpoints = numbers

A

G1
S
G2
Metaphase

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31
Q

Stages of mitosis

A

prophase + metaphase + anaphase + telophase

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32
Q

Mitosis

A

process of nuclear division by which two genetically identical daughter nuclei are produced that are also genetically identical to the parent cell nucleus

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33
Q

Where does growth in plant occur

A

Meristem

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34
Q

How can root tip meristems be studies for mitosis

A

using the squash technique (root tips are stained and then gently squashed, spreading the cells out into a thin sheet and allowing individual cells undergoing mitosis to be clearly seen)

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35
Q

Method to view mitosis in plants

A

Method
• Garlic or onion (Allium cepa) root tips are most commonly used (the bulbs can be encouraged to grow roots by suspending them over water for a week or two)
Remove the tips of the roots (about 1cm) and place in a suitable stain (eg. warm, acidified acetic orcein, which stains chromosomes a deep purple)
• The stained root tip is gently squashed on a glass slideusing a blunt instrument (eg. the handle of a mounting needle)
• Cells undergoing mitosis are seen

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36
Q

What does prophase look like

A

Big blob mess

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37
Q

What does metaphase and anaphase look like

A

Metaphase = kinda see the chromosome lines
Anaphase = pulling apart

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38
Q

Limitations of method

A

It can be very difficult to distinguish between prophase and telophase in cells
• The size of cells or structures of tissues may appear inconsistent in different specimen slides
• Optical microscopes do not have the same magnification power as other types of microscopes and so there are some structures that can not be seen
• The treatment of specimens when preparing slides could alter the structure of cells

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39
Q

If there are multiple nuclei in one cell what stage is it in

A

Telophase

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40
Q

How is mitosis important in asexual reproduction

A

For unicellular organisms such as Amoeba, cell division results in the reproduction of a genetically identical offspring
• For multicellular organisms, new individuals grow from the parent organism (by cell division) and then detach (‘bud off) from the parent in different ways

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41
Q

Asexual reproduction

A

the production of new individuals of a species by a single parent organism - the offspring are genetically identical to the parent

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42
Q

Examples of organisms with asexual reproduction

A

Yeast

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43
Q

The quicker the s phase…

A

The lower chance of mutations occurring

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44
Q

Graph for mass of DNA at each stage

A
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45
Q

Define meiosis

A

orm of nuclear division that results in the production of haploid cells from diploid cells - It produces gametes in plants and animals that are used in sexual reproduction

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46
Q

What is the consequence of a mutation on a tumour suppressant gene?

A

Increases peoples chances of tumours.

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47
Q

Hayflick constant

A

Every cell has a limit of how many times it can divide before it is completely dead = cell life

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48
Q

Cytokinesis in animal cells

A

cell membrane beginning to form furrows which go deeper and deeper inwards until eventually the sections connect and the cell is split into 2 identical daughter cells

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49
Q

Cytokinesis in plant cells

A

vesicles from the Golgi apparatus begin to assemble at the equator. These fuse with eachother and the cell surface membrane divides into 2 new sections

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50
Q

Diploid

A

46 chromosomes

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51
Q

Haploid

A

23 gametes

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52
Q

Prophase 1

A
  • chromosomes shorten and thicken
  • Nuclear envelope breaks down
  • Centriole divides and moves to the opposite poles and the spindle fibre starts forming.
  • Chromosomes come together in the homologous pairs
  • Crossing over (homologous chromosomes can cross over)
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53
Q

Crossing over

A
  • prophase 1

homologous chromosomes can cross over) this means that they exchange alleles between the non sister chromatid within a homologous pair . This means that the alleles shuffle over - opportunity to create genetic variation as the alleles can swap (happens in either prophase or metaphase) the amount of variation depends on the distance between the crossover points because there’s more variation the further apart the cross over happens

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54
Q

What does DNA look like in prophase 1

A

• DNA replication has already occurred so each chromosome consists of two sister chromatids joined together by a centromere

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55
Q

What is a bivalent

A

OA pair of homologous chromosomes

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56
Q

Metaphase 1

A
  • homologous chromosomes line up along the equator
  • Spindle fibre attaches to the centromere (middle of a chromosome)
  • The maternal and paternal chromosomes in each pair position themselves
    independently of the others = independent assortment
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57
Q

Independent assortment

A

maternal and paternal chromosomes in each pair position themselves independently of the others

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58
Q

Anaphase 1

A
  • spindle fibres contract
  • Chromosomes are pulled to the opposite ends
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59
Q

Telophase 1

A

chromosomes arrive at opposite poles
• Spindle fibres start to break down
• Nuclear envelopes form around the two groups of chromosomes + nucleoli reform

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60
Q

What do some plant cells do that’s different to normal cels

A

• Some plant cells go straight into meiosis Il without reformation of the nucleus in telophase I

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61
Q

What are the sites where crossing over happens called

A

Chiasmata

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62
Q

What happens in cytokinesis 1

A

• division of the cytoplasm
• Cell organelles =. distributed between two developing cells
• The end product of cytokinesis in meiosis I is two haploid cells

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63
Q

Prophase 2

A
  • chromosomes shorten and condense
  • Nuclear envelope breaks down
  • Centriole moves to the opposite poles
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64
Q

Metaphase 2

A
  • chromosomes line up along the equator
  • Spindle fibres attach to the centromere of the chromosomes
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65
Q

Anaphase 2 nt

A
  • Chromatids are pulled apart to opposite poles by spindle fibres (spindle fibres contract
  • The chromatids going to either side
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66
Q

Telophase 2

A
  • nuclear envelope starts forming
  • Creates 4 haploid cells
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67
Q

Significance of meiosis

A

increase the genetic diversity of gametes produced

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68
Q

Genetic diversity in meiosis

A

• crossing over
• independent assortment
• random fusion of gametes
• mutations ( not strictly meiosis)

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69
Q

Crossing over

A

process by which non-sister chromatids exchange aleles

70
Q

When does independent assortment happen

A

Metaphase 1 + 2

71
Q

How to work out the number of different possible chromosome combinations = independent assortment

A

2n can be used, where n corresponds to the number of chromosomes in a haploid cell

72
Q

How do mutations increase genetic diversity

A

random mutation that takes place during DNA replication can lead to the production of new alleles and increased genetic variation.

73
Q

Function of erythrocytes

A

transport oxygen around the body and carbon dioxide to the lungs

74
Q

Adaptions of erythrocytes (3)

A

biconcave in shape which increases the surface area over which oxygen can be absorbed
o cytoplasm contains high amounts of the pigment haemoglobin which can readily bind to oxygen
o No nucleus = makes more space inside the cell for haemoglobin molecules for
maximum oxygen-carrying capacity

75
Q

Function of neutrophils

A

destroy pathogens by phagocytosis and the secretion of enzymes

76
Q

Adaptations of neutrophils

A

Lobed nucleus= allows them to squeeze through cell junctions in the capillary wall

Many lysosomes = digestive enzymes help to digest and destroy
invading cells

Many mitochondria

77
Q

Function of squamous epithelial cells

A

provide a surface covering or outer layer.
Found on a variety of organs and structures e.g. blood vessels and alveoli

78
Q

Adaptations of squamous epithelial cells

A

o layer forms a thin cross-section which reduces the distance that substances have to move to pass through - it shortens the diffusion pathway
o It is permeable, allowing for the easy diffusion of gases

79
Q

Function of ciliated epithelial cells

A

moving substances across the surface of a tissue

80
Q

Adaptations of ciliated epithelial cells

A

Have cilia = move in rhythm to move mucus + trapped pathogens from lungs
• Goblet cells secrete mucus = trap dust, dirt and microorganisms - preventing them from entering vital organs where they may cause infection

81
Q

Function of sperm cells

A

reproduction - to fuse with an egg, initiate the development of an embryo and pass on fathers genes

82
Q

Adaptations of sperm cells

A
  • Loads of mitochondria to provide energy that is needed to move the tail towards the egg
  • Specialised enzymes (digestive enzymes) in the acrosome to digest the egg
  • Long and thing so they can move easily
83
Q

Unspecialised cells

A

all the genes are switched on = Initially cells have the ability of becoming any cell

84
Q

Pros of differentiating

A

when certain genes are switched off, some are expressed more = in doing so the number of organelles change, the shape of the cell changes, the content of the cell changes

85
Q

Palisade cell function

A

carry out photosynthesis to produce glucose and oxygen

86
Q

Adaption of palisade cells

A
  • Long and cylindrical so they can pack together quite well, allowing short diffusion for carbon dioxide and oxygen
  • Loads of chloroplast to carry out photosynthesis
  • Large vacuole which allows chloroplast to be pushed to the edges = easy access to sunlight
87
Q

Function of root hair cell

A

absorption of water and mineral ions from soil

88
Q

Adaptations of root hair cells

A

Root hair = increase SA = rate of water uptake by osmosis is greater
o Thinner walls = water can move through easily (due to shorter diffusion
distance)
o Mitochondria for active transport of mineral ions

89
Q

Function of guard cells

A

control the opening of the stomata to regulate water loss and gas exchange

90
Q

Adaptations of guard cells

A
  • Control the opening and closing of the stomata by either swelling up or losing water
  • Lots of mitochondria for active transport
  • Have chloroplast but can’t photosynthesise because they don’t have the enzymes for the later stages
91
Q

Tissue

A

group of cells that work together to perform a specific function

92
Q

What forms the epithelial tissue

A

Epithelial cells = function = absorb food in small
intestine

93
Q

Squamous epithelial

A

Thin and found in exchange surfaces which need short diffusion distances (alveoli

94
Q

Ciliated epithelial

A

In areas to prevent entry of pathogens and move mucus e.g. in the lungs (trachea) because they move substances along

95
Q

Organ

A

a group of tissues that perform together for a specific function

96
Q

Organ system

A

groups of organs that perform together for a function

97
Q

Heart as an organ is made up of what

A

cardiac muscle tissue, blood vessel tissues and
connective tissue

98
Q

Connective tissues

A

Connect structures together and provide support e.g. cartilage, bones

99
Q

3 types of cartilage

A

Hyaline
Fibrous
Elastic

100
Q

Cartilage function

A

prevent things from collapsing = provides support + holds structures together

101
Q

Function of xylem cells

A

transport water for tissue and dissolved ions

102
Q

Adaptations of xylem cells

A

o No top and bottom walls between cells to form continuous hollow tubes through which water is drawn upwards towards the leaves by transpiration
o Cells are essentially dead, without organelles or cytoplasm, to allow free movement of water
o Outer walls are thickened with a substance called lignin, strengthening the tubes, which helps support the plant

103
Q

Function of phloem cells

A

Transport of dissolved sugars and amino acids

104
Q

Adaptations of phloem cells

A

Made of living cells which are supported by companion cells
o joined end-to-end and contain holes in the end cell walls (sieve plates) forming tubes that allow sugars and amino acids to flow easily through (by translocation)
o have very few subcellular structures to aid the flow of materials

105
Q

Function of muscle cells

A

Contraction for movement

106
Q

Adaptations of muscle cells

A

have layers of protein filaments in them, these layers can slide over each other causing muscle contraction
o have a high density of mitochondria to provide sufficient energy (via respiration) for muscle contraction
o Skeletal muscle cells fuse together during development to form multinucleated cells that contract in unison

107
Q

3 types of muscle in animal

A
  • skeletal muscles
  • Cardiac muscles
  • Smooth muscles
108
Q

Hyaline cartilage

A

Found on the outside of bones and prevents bones from rubbing together and creating friction

109
Q

Fibrous cartilage

A

Mainly between discs and the back and in the knee joints

110
Q

Elastic cartilage

A

Soft cartilage

111
Q

Stem cells

A

Cells that can divide by mitosis an unlimited number of times

112
Q

Potency

A

ability of stem cells to differentiate into more specialised cell types

113
Q

3 types of potency

A

Totipotent
Pluripotent
Multi potent

114
Q

Totipotency

A

stem cells that can differentiate into any cell type found in an embryo, as well as extra-embryonic cells

115
Q

Pluripotent

A

embryonic stem cells that can differentiate into any cell type found in an embryo but are not able to differentiate into extra-embryonic cells

116
Q

Multipotency

A

adult stem cells that have lost some of the potency associated with embryonic stem cells and are no longer pluripotent

117
Q

Adult stem cells

A

small numbers of stem cells remain to produce new cells for the essential processes of growth, cell replacement and tissue repair

118
Q

What are adult stem cells

A

Multi potent

119
Q

Stem cells in bone marrow

A

Multi potent - only differentiate into blood cells

120
Q

Chondrocytes

A

Mature Cells involved in cartilage tissues

121
Q

Chondroblasts

A

Immature cells involved in cartilage tissues

122
Q

Meristem cells

A

Stem cells in plant

123
Q

What can stem cells be used to repair

A
  • damaged tissues specifically in neurological conditions (e.g. Alzheimer’s and Parkinson’s both are caused by the degeneration of the nerve cells so the treatment is to create these nerve cells in the lab and then put them back into the patient)
  • diabetes to make new pancreatic cells
124
Q

Stem cells in drug research

A

where stem cells can be turned into the type of human tissue you want. Drugs can be tested on those instead of animals

125
Q

Induced pluripotent stem cells

A

Induce normal cells to create stem cells in labs

126
Q

Where are stem cells found in plants

A

Stem cells are found in the meristem tissue = tip of root and shoot of plants

127
Q

Cambium

A

xylem and phloem are formed from stem cells that are found in the tissue
between them = tissue = cambium

128
Q

What is cambium

A

A meristem

129
Q

Meristem

A

any undifferentiated tissue in a plant that has the ability to give rise to new cells

130
Q

Changes that occur when differentiating into xylem

A

Cell elongation, deposit lignin and end walls break down

131
Q

Changes that occur when differentiating into phloem

A

lose some of their cytoplasm and organelles, and develop sieve plates

132
Q

When are embryonic stem cells totipotent

A

if taken in the first 3-4 days after fertilisation

133
Q

When are embryonic stem cells pluripotent

A

if taken on day 5

134
Q

Why is there ethical objections to using embryonic stem cells as research

A

embryos have the potential to develop into human
beings

135
Q
A

A

136
Q
A

A

137
Q
A

D

138
Q
A

B

139
Q
A

D

140
Q

ii

A
141
Q

ii

A
142
Q
A
143
Q

ii

A
144
Q

Suggest why Hydra reproduces asexually when conditions are favourable

A

genetically identical offspring v
offspring produced , rapidly / in large numbers V
(all) offspring will, find conditions favourable / have same adaptations

145
Q

Draw metaphase

A
146
Q
A
147
Q

Why would the student T-test not be suitable

A
148
Q
A
149
Q

Draw anaphase

A
150
Q

ii

A
151
Q

Explain how the organisation of homologous chromosomes during metaphase 1 increases genetic variation.

A
152
Q
A
153
Q
A
154
Q
  1. Plant growth requires the production of new xylem cells.
    Describe how new xylem cells are produced.
A
155
Q
A
156
Q
A
157
Q

Explain the difference between muscle tissue and a muscle.

A

muscle tissue is a group of cells which contract together (1)
a muscle is an organ that consists of muscle tissue and other (named)
tissues working together (1)

158
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159
Q

Explain why a plant leaf is described as an organ.

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160
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161
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162
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163
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164
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Explain why the cells of the inner cell mass are not totipotent stem cells.

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165
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Do all of the questions 😠

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166
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ii

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167
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168
Q

Name two potential sources of human stem cells and for one source, describe an ethical issue associated with the use of stem cells.

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169
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170
Q

Explain why erythrocytes do not make use of any of the oxygen that they are transporting.

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171
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172
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What events occur during the cell cycle that lead to daughter cells being genetically identical:

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  • checkpoints - explain
  • S phase - semi conservative replication
  • Anaphase: each nucleus would have same set of info when the chromosomes split

Biology Module 2 (11 decks)

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