Topic 2 - Cells And Control Flashcards

1
Q

What is the cell cycle?

A

Series of events taking place in a cell

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2
Q

Name some parts of the cell cycle

A

Cell growth
DNA replication
Cell division

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3
Q

State the three stages of the cell cycle

A

Interphase
Mitosis
Cytokinesis

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4
Q

What is interphase

A

Involves cell growth, synthesis of new organelles and DNA replication

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5
Q

What is the longest stage of the cell cycle?

A

Interphase

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6
Q

What does DNA replication involve?

A

Double helix unzips
DNA bases align next to complementary bases on strands
Complementary base pairs join
2 identical DNA molecules form

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7
Q

What’s a chromosome?

A

A DNA molecule tightly coiled around proteins

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8
Q

What happens to chromosomes during DNA replication?

A

DNA in arm of each chromosome is replicated

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9
Q

What are the arms of the chromosomes called?

A

Chromatids

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10
Q

What is mitosis?

A

Form of cell division - forms 2 diploid daughter cells

Genetically identical to parent cell

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11
Q

Why is mitosis important in organisms?

A

Asexual reproduction
Growth
Repair of damaged cells
Cell replacement

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12
Q

State the 4 stages of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

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13
Q

Outline prophase

A

DNA condenses
Chromosomes become visible
Nuclear membrane disappears

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14
Q

Outline metaphase

A

Chromosomes line up along cell equator

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15
Q

Outline anaphase

A

Spindle fibres attach to each chromosome
Arms of each chromosome pulled to opposite poles
Chromatids separated

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16
Q

Outline telophase

A

Nucleus of cell divides

New membrane forms around each set of chromosomes

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17
Q

What does cytokinesis involve?

A

Division of cell membrane and cytoplasm

2 genetically identical daughter cells produces

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18
Q

A cell divides by mitosis once every 2 minutes. Calculate the number of identical cells present after 10 minutes

A

10/2=5
5 cell divisions taken place
2⁵ = 32 cells

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19
Q

What is cancer

A

Non communicable disease
Uncontrolled cell division (due to damaged DNA) results in formation of primary tumour
Tumour cells break off and spread to other tissues forming secondary tumours

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20
Q

What are percentile charts?

A

Chart used to monitor growth

Measurements can be compared to expected values at certain age

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21
Q

What does the 95th percentile mean?

A

95% of measurements will be below the value of the 95th percentile

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22
Q

What can doctors determine from percentile charts? (3)

A

Slower growth than normal (below bottom line)
Faster growth than normal (above top line)
Abnormal growth (irregular growth patterns)

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23
Q

Describe growth in animals

A

Cell division occurs in all body cells at slower rate in adults than younger animals - growth stops + cell division only required for repairs

Most cells differentiate at early stage + become specialised.

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24
Q

Describe growth in plants

A

Cell division only occurs in meristematic tissue. Rate remains same through life.
Meristematic stem cells can differentiate into any cell type.
Cell elongation occurs in all cells. They expand and enlarge = growth

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25
Q

What are stem cells?

A

Cells that are unspecialised and capable of differentiating into a range of different cell types.

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26
Q

What is meant by differentiation?

A

Process where stem cells become specialised

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27
Q

Why is cell differentiation important?

A

Enables formation of specialised tissues with specific funtions

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28
Q

What are embryonic stem cells?

A

Stem cells found in very early embryos that are unspecialised and capable of differentiating into any cell type

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29
Q

What is the function of embryonic stem cells?

A

Enable growth and development of tissues in human embryos

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30
Q

What are adult stem cells?

A

Stem cells that can differentiate into a limited range of cell types

31
Q

Give an example of an adult stem cell

A

Bone marrow stem cells

32
Q

What’s the primary function of adult stem cells?

A

Replacement of dead cells

Eg replacement of red blood cells which only live for 120 days

33
Q

Where are stem cells found in plants?

A

Meristems

34
Q

Where is meristem tissue found?

A

In regions of the plant where cells are continuously dividing - eg root tips, shoot tips

35
Q

What are meristematic stem cells?

A

Stem cells found in meristems that are unspecialised and capable of differentiating into any cell type during the plants life

36
Q

How can stem cells be used in medicine?

A

Stem cells collected
Stimulated to differentiate into specific cell types
Specialised cells transplanted into patient
Used to treat damage or disease

37
Q

Where can embryonic stem cells be collected from?

A

Donor stem cells removed from embryos grown in vitro

Patients own stem cells removed from the umbilical blood before birth

38
Q

What are the benefits of using stem cells in medicine? (4)

A

Treat damage or disease eg: heart disease
Treat diseases that would otherwise be untreatable
Used in scientific research
Growing organs for transplants

39
Q

What are the risks of stem cell use in medicine? (6)

A

Transplanted stem cells could cause tumours
Finding suitable donors is difficult
May be rejected by body
Potential side effects
Long term risks unknown
May become contaminated during prep and transmit infections to patient

40
Q

What are the ethical issues related to the use of stem cells in medicine? (2)

A

The embryos that were used to provide stem cells are destroyed which is seen as unethical and a waste of human life
May lead to reproductive cloning of humans

41
Q

What is the central nervous system?

A

Brain and spinal cord

42
Q

What is the spinal cord?

A

A long thin structure composed to neurones that extends from medulla oblongata down spine

43
Q

What’s the function of the spinal cord?

A

Connects peripheral NS to brain

44
Q

Describe structure of brain

A

3 main regions:
Cerebrum
Cerebellum
Medulla oblongata

45
Q

Describe the structure of the cerebrum

A

Largest region of brain

Divided into 2 hemispheres

46
Q

What is the function of the cerebrum?

A
Involved in:
Intelligence
Language
Memory
Emotion
Visual and sensory processes
47
Q

What is the function of each cerebral hemisphere?

A

Left receives sensory info from right side of body and controls muscle coordination on right

Right received sensory info from left side of body and controls muscle coordination on left

48
Q

Where is the cerebellum located?

A

Lower region of brain

49
Q

What’s the function of the cerebellum?

A

Involved in:
Coordination of muscles
Voluntary movement - walking
Non voluntary movement - balance

50
Q

What’s the function of the medulla oblongata?

A

Controls automatic processes in the body eg: breathing rate, heart rate

51
Q

What methods, other than surgery, are used by doctors to observe the brain?

A

CT scan

PET scan

52
Q

What is a CT scan?

A

Procedure that uses X rays to produce 3D cross-sectional images of the brain

53
Q

Describe how CT scans are useful to investigate brain function

A

Show damaged regions of brain (areas of swelling/bleeding)

Observations of symptoms can enable scientists to determine function of damaged region

54
Q

What does a PET scan involve?

A

Radioactive substance injected into patients bloodstream and taken up by tissues in brain.
Radiated emitted by tissues detected, enabling identification of active and inactive brain regions.

55
Q

Describe how PET a scans are useful to investigate brain function

A

Show which areas are active/not

Comparisons between healthy and brain damaged allow determine functions of inactive regions

56
Q

Why is it difficult to treat damage to the CNS?

A

Damage to neurones is permanent and can’t be repaired (nerve cells don’t divide by mitosis).
Hard to reach some areas of brain.
Risk of further damage to other areas in surgery.

57
Q

What is the function of the nervous system?

A

Allows an organism to rapidly react to environmental and internal changes

58
Q

What are neurones?

A

Nerve cells adapted to quickly transmit nerve impulses. The functional units of the NS.

59
Q

What is the function of the axon?

A

Carries impulses away from the cell body

Enables transmission of nerve impulses over long distances

60
Q

What’s the function of the dendrites and dendrons?

A

Carry impulses towards cell body

Provide large surface area to receive impulses

61
Q

What’s the role of the myelin sheath?

A

Electrically insulating layer

Surrounds axon and increases speed of impulses

62
Q

Outline the function of a sensory neurone

A

Carries impulses from receptors to the CNS

63
Q

Describe the structure of a sensory neurone

A

Long dendron carries impulses from receptor to cell body
Cell body found halfway down neurone
Short axon carries impulses from cell body to CNS

64
Q

Outline the function of a motor neurone

A

Carries impulses from CNS to effectors

65
Q

Describe the structure of a motor neurone

A

Short dendrites carry impulses from CNS to cell body
Cell body found at one end of the neurone
Long axon carries impulses from cell body to effectors

66
Q

Outline function of relay neurone

A

Carries impulses from sensory neurones to motor neurones within CNS

67
Q

Describe structure of relay neurone

A

Short dendrites carry impulses from sensory neurones to cell body
Short axon carries impulses from cell body to motor neurones

68
Q

Describe how the CNS coordinates a response to a stimulus

A

Stimulus
Sensory receptor detects stimulus
Sensory receptor sends impulses along sensory neurone to CNS
CNS coordinates response
CNS sends info to effector along motor neurone
Effector produces a response to the stimulus

69
Q

What is a synapse?

A

A small gap between neurones across which a nerve impulse is transmitted via neurotransmitters

70
Q

How are nerve impulses transmitted across a synapse?

A

Nerve impulses reach presynaptic neurone
Triggers release of neurotransmitters
Neurotransmitters diffuse across synapse
Bind to receptors on postsynaptic neurone
Stimulates impulse in postsynaptic neurone

71
Q

Why do synapses slow down the transmission of nerve impulses?

A

Takes time for the neurotransmitters to diffuse across the synapse and bind to receptors on the postsynaptic neurone

72
Q

What is a reflex?

A

Automatic response to a stimulus by the body
Involuntary - doesn’t involve conscious part of brain
Protective mechanism eg a withdrawal reflex is initiated when a hot object is touched to prevent burns

73
Q

Describe the reflex arc

A

Stimulus -> sensory receptor -> sensory neurone -> relay neurone -> motor neurone -> effector -> response