2: Cells and Control Flashcards
1
Q
Gene
A
Short section of DNA
2
Q
Diploid cell
A
46 chromomosomes (23 pairs)
3
Q
Haploid cell
A
23 chromosomes
4
Q
Why is mitosis important
A
Replaces damaged cells and helps in asexual reproduction
5
Q
What does mitosis produce
A
2 genetically identical diploid daughter cells
6
Q
Cell cycle stages
A
Interphase, Mitosis, Cytokinesis
7
Q
Interphase
A
The cells grows, organelles increase in number, protein synthesis occurs, DNA is replicated and energy stores are increased
8
Q
Cytokinesis
A
The cytoplasm and cell membrane divide to form two separate cells
9
Q
Order of mitosis
A
Prophase, Metaphase, Anaphase, Telophase
10
Q
Prophase
A
The chromosomes condense, getting shorter and fatter. The membrane around the nucleus breaks down and the chromosomes lie free in the cytoplasm
11
Q
Metaphase
A
The chromosomes align at the cell equator
12
Q
Anaphase
A
The chromatids are pulled to opposite ends of the cell by spindle fibres
13
Q
Chromatid
A
One ‘arm’ of a replicated chromosome
14
Q
Telophase
A
Nuclei form around each of the sets of chromosomes.
15
Q
Cell differentiation
A
The process by which a cell changes to become specialised for its job
16
Q
What does cell differentiation allow multicellular organisms to do
A
Work more efficiently
17
Q
Cell division
A
Mitosis
18
Q
Cell elongation
A
When a cell expands, making the cell bigger and making the organism grow
19
Q
Types of growth in animal cells
A
Cell division, cell differentiation
20
Q
Cell division in animals
A
Occurs when they are younger. When the animal is an adult cell division is mostly for repair.
21
Q
Cell differentiation in animals
A
Usually lost at an early age
22
Q
Where does cell division happen in plants
A
Tips of the roots and shoots
23
Q
What is the main cause of growth in height of plants
A
Cell elongation
24
Q
Cell differentiation in plants
A
Plants grow continuously, so plants will continue to differentiate to grow new parts
25
What is a percentile chart used for
Monitoring a child's growth over time
26
Why are percentile charts used
To check a baby is growing normally
27
Percentile
The % of data equal or lower than the given value
28
Cancer
Uncontrolled cell division
29
What controls the rate of cell division
Genes in an organisms DNA
30
What causes uncontrolled cell division
A change in one of the genes that controls cell division
31
Tumour
A mass of abnormal cells
32
What can a tumour do
Invade and destroy surrounding tissue
33
Stem Cell
Can differentiate into different types of cells
34
What are undifferentiated cells called
Stem cells
35
What cells are found in early human embryos
Embryonic stem cells
36
Embryonic stem cell
Can differentiate into any type of cell
37
What are stem cells important for
Growth and development of organisms
38
Where are adult animal stem cells found
Bone marrow
39
Adult animal stem cell
Can differentiate but only into certain types of cells
40
What are adult animal stem cells used for
To replace damaged cells
41
Where is meristem tissue
The roots and shoots of the plants
42
What do meristems contain
Plant stem cells
43
What do meristems produce
Unspecialised cells
44
Plant stem cell
Can differentiate into any type of cell
45
Examples of specialised tissues plant stem cells form
Xylem and phloem
46
What are stem cells used for today
Doctors use adult stem cells to cure some diseases
47
Medical research involving embryonic stem cells
Scientists have extracted embryonic stem cells from human embryos and can stimulate them into specialised cells under certain conditions
48
What could stem cells be used for in the future
Creating specialised cells to replace those damaged by disease or injury
49
Risks of stem cell transplants
Rejection, tumour development and disease transmission
50
Why might stem cell transplant rejection happen
The patients body might recognise that the stem cells are foreign and trigger an immune response
51
Why might stem cell transplant cause tumour development
Stem cells divide very quickly. If scientists are unable to control the rate of division, a tumour may develop
52
Why might stem cell transplant cause disease transmission
Viruses live inside cells. If donor stem cells are infected with a virus, they could be passed onto the recipient
53
Major argument against stem cells in medicine
Ethical issues
54
Ethical issues relating to stem cells in medicine
An embryonic stem cell is a human life and they shouldn't be used for experiments
55
CNS
Central Nervous System
56
Stimulus
Change in your environment
57
Neurone
Nerve cell
58
Sensory receptor
Detects the stimulus
59
What happens after a stimulus is detected
The information is converted into an electrical impulse
60
Order of steps in the nervous system
Stimulus, receptor, sensory neurone, CNS, motor neurone, effector, response
61
Reaction time
The time it takes you to respond to a stimulus
62
Axon
Carry nerve impulses away from the cell body
63
Dendrons/dendrites
Carry nerve impulses towards the cell body
64
Myelin sheath
An electrical insulator around the axon, speeds up the impulse
65
Why are neurones long?
If they are long, the impulse is faster as the impulse slows whenever it is transferred to another neurone
66
Sensory neurone
Carries nerve impulses from receptor cells to the CNS
67
Motor neurone
Carries nerve impulses from the CNS to effector cells
68
Myelinated
Neurones with a myelin sheath
69
Relay neurone
Carries nerve impulses from sensory neurones to motor neurones
70
Synapse
The gap between two neurones
71
What happens to nerve impulses at the synapse
Transferred into chemicals called neurotransmitters which diffuse across the gap
72
What happens when the neurotransmitters reach the next neurone
A new electrical impulse is set off
73
Why do synapses slow the transmission of electrical impulses
It takes time for the neurotransmitters to diffuse across the synapse
74
Reflex
Automatic, rapid responses to stimuli
75
Why are reflexes quicker than normal reponses
You don't have to spend time thinking about them
76
Where are relay neurones
The CNS
77
What is the purpose of the reflex in the eye
Protects the eye from very bright light
78
What happens to the eye after a motor neurone returns from seeing bright light
The circular muscles in the iris contract
79
Spinal cord
Relays information between the brain and the rest of the body
80
What is the brain made of
Billions of interconnected neurones
81
Cerebrum
Largest part of the brain, divided into two halves called cerebral hemispheres
82
Another name for the cerebrum
Cerebral cortex
83
What does the cerebrum control
Movement, intelligence, memory, language and vision
84
Cerebellum
Responsible for muscle coordination and balance
85
Medulla oblongata
Controls unconscious activities like breathing and you heart rate
86
How do you look inside the brain without surgery
Brain scanners
87
CT scanner
Uses X-rays to produce an image of the brain
88
What does a CT scan show
Main structures of the brain but doesn't show their functions
89
How to work out the function of an area of the brain with a CT scan
Look at a patient that has lost a function and identify the damaged area of their brain
90
PET scanner
Uses radioactive chemicals to show which parts of the brain are active
91
What does a PET scan show
The structure and function of the brain in real time
92
Central nervous system
The brain and spinal cord
93
What are PET scans useful for
They show if areas of the brain are unusually active or inactive so they are useful for studying disorders that change the brain's activity
94
Why is it hard to repair damage in the CNS
Neurones don't repair themselves and scientists haven't developed a way to repair nervous tissue in the CNS
95
Risk of treating the spinal cord
The operation could damage it further
96
Why can't we treat brain tumours
It's hard to access them and it's not possible to surgically remove them
97
Cornea
Refracts light into the eye
98
Iris
Controls how much light enters the pupil
99
Pupil
The hole in the centre of the eye
100
Lens
Refracts light, focusing it onto the retina
101
Retina
Light sensitive part of the eye covered in rod and cone cells
102
What type of cells are rod and cone cells
Receptor cells
103
Rod cell
Sensitive to dim light, but not to colour
104
Cone cell
Sensitive to colour but not dim light
105
What do rod and cone cells do
Convert light into electrical impulses
106
Optic nerve
Carries electrical impulses from the eye to the brain
107
Colour blind
You can't tell the difference between certain colours
108
What causes colour blindness
There aren't enough cones in the retina or the cones aren't working properly
109
Why isn't there a cure for colour blindness
Cone cells can't be replaced
110
Cataract
Cloudy patch on the lens which stops light from being able to enter the eye normally
111
Symptoms of cataracts
Blurred vision, colours look less vivid, difficulty seeing in bright light
112
How to treat a cataract
Replace a normal lens with an artificial one
113
What causes long-sightedness
The lens is the wrong shape and doesn't bend light enough or the eyeball is too short
114
How does long sightedness work
The light from near objects is brought into focus behind the retina
115
How to fix long-sightedness
Glasses or contact lenses with a convex lens
116
What causes short-sightedness
The lens is the wrong shape and bends the light too much or the eyeball is too long
117
How does short-sightedness work
Light from distant objects is brought to focus infront of the retina
118
How to fix short-sightedness
Glasses or contact lenses with a concave lens
119
Ciliary muscle
Controls the suspensory ligaments
120
Suspensory ligaments
Change the shape of the lens
121
Ciliary muscle when viewing close objects
Contracts
122
Suspsenory ligament when viewing close objects
Loosens
123
The lens when viewing close objects
More rounded shape
124
Amount of light refracted when viewing close objects
More
125
Ciliary muscle when viewing distant objects
Relaxes
126
Suspensory ligaments when viewing distant objects
Pulls tight
127
The lens when viewing distant objects
Less rounded shape
128
Amount of light refracted when viewing distant objects
Less
