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Biology - OCR A > 2.6 - Cell Division, Diversity And Organisation > Flashcards

2.6 - Cell Division, Diversity And Organisation Flashcards

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1
Q

What makes up a chromatin?

A

DNA and Histones

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2
Q

What is a chromatin called when it is visible?

A

A chromosome

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3
Q

What are the 2 main parts of the cell cycle?

A

Interphase and the mitotic phase

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4
Q

What are the 3 main points in interphase?

A

G1, S and G2

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5
Q

What happens in G1?

A

The cell contents duplicate and the cell gets bigger

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6
Q

What does the G1 checkpoint do?

A

It ensures that there is nothing wrong so the cell can go into S phase

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7
Q

What happens in the S phase?

A

The 46 chromosomes are duplicated

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8
Q

What happens in the G2 phase?

A

The cell caries on growing

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9
Q

What happens at the G2 checkpoint?

A

It checks the DNA for damage

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10
Q

What can happen to a cell before it enters the S phase?

A

It can go into the G0 phase

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11
Q

What happens in the G0 phase?

A

The cell leaves the cycle due to:
- Cell differentiation
- DNA damage
- Senescence (the cell is to old)

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12
Q

Is the G0 phase permanent?

A

It can be or it can be temporary

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13
Q

What does a chromosome look like?

A

It is one chromatid with a centromere

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14
Q

What is it called when there are 2 chromatids joined together?

A

Sister chromatids

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15
Q

What is mitosis?

A

It is the part of the cell cycle where nuclear division takes place

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16
Q

What are the products of mitosis?

A

2 genetically identical daughter cells

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17
Q

What are the 4 phases of mitosis?

A
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
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18
Q

What happens in prophase?

A
  1. The DNA condenses (supercoiling)
  2. Chromosomes become visible
  3. The nuclear envelope breaks down
  4. The centrioles move to the poles of the cell
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19
Q

What happens in metaphase?

A
  1. The chromosomes line up at the equator
  2. The centrioles spindle and attach to the centromeres
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20
Q

What happens in anaphase?

A
  1. The centromeres divide
  2. The spindle fibres contract and shorten because of motor proteins
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21
Q

What happens in telophase?

A
  1. The chromosomes condense
  2. A nuclear membrane forms around the chromosomes
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22
Q

What is cytokinesis?

A

This is when the cell splits into 2

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23
Q

When does cytokinesis happen?

A

It happens after telophase in both mitosis and meiosis

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24
Q

How do you work out the mitotic index?

A

The number of condensed chromosomes
————————————— X100
The total number of cells

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25
Q

What is a haploid cell

A

A cell containing 23 chromosomes

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26
Q

What are examples of a haploid cells?

A

An egg cell and sperm cell

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27
Q

What is a haploid cell called in meiosis?

A

A gamete

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28
Q

What is a diploid cell?

A

A cell containing 48 chromosomes

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29
Q

What are examples of diploid cells?

A

Body cells

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30
Q

What is the male chromosome?

A

XY

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31
Q

What is the female chromosome?

A

XX

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32
Q

What are the 2 main parts of meiosis?

A

Meiosis 1 and meiosis 2

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33
Q

Do cells go straight into meiosis 2?

A

Only some plant cells, animal cells have a break

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34
Q

What is the difference between prophase and prophase 1?

A

In prophase 1 the chromatids do something called ‘crossing over’

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35
Q

What is crossing over?

A

The chromatids from different homologous pairs twist around each other and parts swap

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36
Q

What is the deference between metaphase and metaphase 1?

A

In metaphase 1 the cells undergo independent assortment when lining up at the equator

37
Q

What is independent assortment?

A

When they line up on the equator randomly so the spindles pull back different homologous pairs, so there are multiple options of combinations

38
Q

What is the difference between anaphase 1 and anaphase 2?

A

In anaphase 1 it pulls the chromosome pairs to opposite side not the chromatids

39
Q

What is the product of meiosis?

A

4 genetically different daughter cells

40
Q

What is mitosis and example of?

A

Asexual reproduction

41
Q

What is meiosis an example of?

A

Sexual reproduction

42
Q

What is an homologous pair?

A

Two chromosomes that join together, 1 from the egg and 1 from the sperm

43
Q

What is a stem cell?

A

An undifferentiated cell that has the ability to turn into different types of cells

44
Q

What does pluripotent mean?

A

The ability to differentiate into any type of cell (eg. Embryonic stem cells)

45
Q

What can stem cells do before they differentiate?

A

They can divide by mitosis to make more cells

46
Q

What are the different types of stem cells?

A

Human:
- Embryonic stem cells
- Adult stem cells

Plants:
- Meristem tissue

47
Q

Where are embryonic stem cells found?

A

In a blastocyst (when the zygote begins to divide)

48
Q

Where are adult stem cells found?

A

They are found in:
- Blood
- Brain
- Muscle
- Bone
- Adipose tissue (fat storage)
- Skin

49
Q

Where else can stem cells be found?

A
  • Umbilical-cord blood
  • iPS cells
50
Q

What are iPS cells?

A

Differentiated cells that are reprogrammed in a lab to turn on a certain gene to become undifferentiated again

51
Q

What are stem cells used for?

A
  • Bone marrow transplant
  • Drug research
  • Developmental biology
52
Q

Why are stem cells used in bone marrow transplants?

A

To treat diseases of the blood and immune system (eg. Leukaemia and SCID

53
Q

Why are stem cells used in drug research?

A

To test new drugs so they don’t have to test on animals

54
Q

How are stem cells used in developmental biology?

A
  • To study how the cells develop
  • To learn how cells function and what happens when they are diseased
  • To find out if they can extend the capacity that embryos have for growth and repair in later life
55
Q

What are stem cells going to be able to treat in the future?

A
  • Type 1 diabetes
  • Liver disease
  • Alzheimer’s
  • Parkinson’s
  • Spinal injuries
  • Used a bioscaffolding for growing organs
  • Strokes
  • Burns
    Heart disease
56
Q

What does totipotent mean?

A

The ability of a single cell to divide and produce all the differentiated cells in an organism

57
Q

What does multipoint mean?

A

The capacity of stem cells to differentiate into particular cell types

58
Q

Why do multicellular organisms need cell differentiation and specialisation?

A

They have a small SA:Volume ratio so most of the cell is not in direct contact with the environment

59
Q

What does differentiation in animal cells cause?

A
  • Different proportion of organelles
  • The shape of the cell changes
  • Some contents of the cell change
60
Q

What are types of specialised animal cells?

A
  • Erythrocytes (blood cells)
  • Neutrophils(white blood cells that ingest pathogens
  • Spermatozoa
  • Epithelial cells
61
Q

What does an erythrocyte do?

A

It carries oxygen from the lungs to respiring cells

62
Q

How are erythrocytes specialised?

A
  1. It has a biconcave shape to increase surface area
  2. It has no nucleus so there is more space for heamoglobin
  3. It has an elastic membrane so that it can change shape easily to fit through the capillaries
  4. The cytoplasm contains lots of haemoglobin for oxygen to bind to
63
Q

What does a neutrophil do?

A

It injest pathogens

64
Q

How is a neutrophil specialised?

A
  1. They have a flexible shape to fit through junctions
  2. The flexibility allows them to engulf pathogens
  3. Contains lots of lysosomes to help digest pathogens
65
Q

What does a spermatozoa do?

A

It fuses with the egg cell in reproduction to share their genes

66
Q

How is the spermatozoa specialised?

A
  1. It has a nucleus containing 23 chromosomes
  2. It has acrososome in its head that contains digestive enzymes to help break down the outer layer of the egg cell
  3. It has lots of mitochondria to release energy so that it can move
  4. The flagellum rotates so it can move to the egg cell
67
Q

What are the the 3 specialised plant cells?

A
  1. Root hair cells
  2. Guard cells
  3. Palisade cells
68
Q

What does a root hair cell do?

A

It absorbs water and mineral ions from the soil

69
Q

How is a root hair cell specialised?

A
  1. They have hairs to increase the surface area
  2. Thin walls for a short diffusion pathway
  3. A permanent vacuole with cell sap to maintain the water potential gradient
  4. Mitochondria for active transport of mineral ions
  5. Special carrier proteins in the plasma membrane to actively transport mineral ions
70
Q

What does a guard cell do?

A

They control the opening of the stomata

71
Q

How is the guard cell specialised?

A
  1. Inner cell walls are thicker and the outer cell walls are thinner for when the cell goes turgid
  2. Chloroplasts for ATP production
72
Q

What do palisade cells do?

A

They carry out photosynthesis to produce glucose and oxygen

73
Q

How is a palisade cell specialised?

A
  1. Lots of chloroplasts to maximise the absorption of light
  2. Tall and thin shape to allow light to penetrate deeper
  3. Cells are densely packed for a short diffusion pathway
  4. A large vacuole near the chloroplasts to create a short diffusion pathway
  5. Motor proteins and cytoskeleton threads to move the chloroplasts closer to the light
74
Q

What are the 4 specialised animal tissues?

A
  1. Cartilage
  2. Muscle tissue
  3. Ciliated epithelium
  4. Squamous epithelium
75
Q

What does cartilage do?

A

It provides support

76
Q

How is cartilage specialised?

A
  1. It is flexible and found all over the body
  2. It separates living cells
  3. It allows other tissues to withstand force
  4. Forms rings along the trachea to support it and keep it open
77
Q

Where is hyaline cartilage found?

A

It makes up the skeleton in the embryo

78
Q

What does muscle tissue do?

A

They contract for movements

79
Q

How is muscle tissue specialised?

A
  1. They have layers of protein filaments so that they can slide over each other
  2. High density of mitochondria
  3. Skeletal muscles fuse together so that they can contract in unison
80
Q

What does ciliated epithelium do?

A

They move substances across the surface of the tissue

81
Q

How is ciliated epithelium specialised?

A
  1. They have cilia that move in coordination
  2. Goblet cells that secrete mucus to trap things so that they cant enter any vital organs
82
Q

What does squamous epithelial tissue do?

A

It provides an outer layer on a variety of organisms (eg. Blood vessels)

83
Q

How is squamous epithelium specialised?

A
  1. They have a single layer of flattened cells along the basement membrane
  2. They have a thin cross-section to increase diffusion
  3. It is permeable so gasses can easily diffuse through
84
Q

What are the 2 types of specialised plant tissue?

A
  1. Xylem vessel cell
  2. Phloem vessel cell
85
Q

What does the xylem vessel cell do?

A

They transport water and dissolved ions

86
Q

How it the xylem vessel tissue specialised?

A
  1. No top or bottom walls so water can move via transpiration
  2. The cells are dead to allow the free movement of water
  3. Has lignin to thicken the walls for support
87
Q

What do phloem vessel cells do?

A

They transport dissolved sugars and amino acids

88
Q

How are phloem vessel cells specialised?

A
  1. Made of living cells that are supported by companion cells
  2. Cells are joined end to end so that things can easily flow
  3. Very few sub cellular structures to aid in the flow of materials

Biology - OCR A (25 decks)

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