cells and control Flashcards
(77 cards)
1
Q
what do chromosomes contain
A
genetic information
2
Q
where is genetic information stored
A
the nucleus of a cell
3
Q
how is genetic information stored
A
chromosomes
4
Q
what are chromosomes
A
coiled up lengths of DNA molecules
5
Q
what is a diploid cell
A
2 copies of each chromosome (normal body cells)
6
Q
where does each copy of the chromosomes come from
A
1 mother
1 father
7
Q
what does mitosis make
A
two identical cells - nucleus contains same number of chromosomes as the original cells
8
Q
what is mitosis for
A
growth and repair
9
Q
what happens in mitosis
A
multicellular organisms divide to produce new cells in the cell cycle.
10
Q
how do multi cellular organisms use mitosis
A
to grow and to replace cells which may have been damaged
11
Q
what is asexual reproduction
A
uses mitosis to reproduce
12
Q
what is the first stage of cell cycle
A
interphase
13
Q
what happens during interphase
A
before it divided, the cell has to grow and increase the amount of sub cellular structures such as mitochondria and ribosomes.
it then duplicates the dna, copied and forms X-shaped chromosomes.
14
Q
what happens after interphase
A
mitosis and cytokinesis
15
Q
what are the four stages of mitosis in order
A
prophase
metaphase
anaphase
telophase
(PMAT)
16
Q
what is prophase
A
the chromosomes condense, getting shorter and fatter.
the membrane around the nucleus breaks down and the chromosomes lie free in the cytoplasm
17
Q
what is metaphase
A
the chromosomes line up at the centre of the cell
18
Q
what is anaphase
A
cell fibres pull the chromosomes apart.
the two arms of each chromosome go to opposite ends of the cell
19
Q
what is telophase
A
membranes form around each of the sets of chromosomes.
these become the nuclei of the two new cells - nucleus has divided
20
Q
what is cytokinesis
A
the cytoplasm and cell membrane divided to form separate cells
21
Q
when does cytokinesis happen
A
happens before telophase ends
22
Q
what is produced by mitosis
A
2 new daughter cells
23
Q
characteristics of the daughter cells
A
- same sets of chromosomes in its nucleus
- genetically identical diploid cells
- genetically identical to the parent cell
24
Q
what is growth
A
increase in size or mass
25
what is cell differentiation
the process by which a cell changes to become specialised for its job
26
what do specialised cells allow
multicellular organisms to work more efficiently
27
what is cell elongation
where a plant cell expands, making the cell bigger and so making the plant grow
28
what is cancer
uncontrolled cell division which results in a mass of abnormal cells called a tumor which invades and destroys surrounding tissues
29
what are percentile charts used for
to monitor growth over time, so overall pattern in development can be seen and any problems highlighted
30
what 3 measurements are taken for percentile charts
length
mass
head circumference
31
what does the chart show
number of percentiles
e.g. the 50th percentile shows the mass that 50% of babies will have reach at a certain age
32
what can stem cells do
can differentiate into different types of cells
33
what are undifferentiated cells called
stem cells
34
how do stem cells differentiate
divide by mitosis to become new cells
35
where are stems cells found in humans
early human embryos
bone marrow
36
what group is a stem cell
embryonic
37
where are stem cells contained in plants
meristems (plant tissue)
38
how can stem cells be used
in medicine, to cure some diseases
39
example of stem cells in medicine
stickle cell anaemia
40
3 potential risk for scientists
1. tumor development - stem cells divide very quickly and scientists are unable to control the rate of cell division
2. disease transmission - viruses are inside cells, if the donor has a virus it could effect the recipient
3. rejection - body may recognise them as foreign and trigger a immune response to get rid of them
41
what is the ethical issue in using stem cells
shouldn’t be used as each one is a ‘potential human life’
42
what is made up of the central nervous system (CNS)
the brain
the spinal cord
neurones
43
what is the spinal cord
a long column of neurones that run from the base of the brain down the spine, at several places, neurones branch off down and connect to other parts of the body
44
what does the spinal cord do
relays information between the brain and the rest of the body
45
what is the cerebrum
largest part of the brain, divided into two halves called the cerebral hemispheres
right - controls muscles on the left side of the body
left - controls muscles on the right side of the body
different parts of the cerebrum are responsible for different things
- movement
- intelligence
- memory
- language
- vision
46
what is the cerebellum
responsible for muscle coordination and balance
47
what is the medulla oblongata
controls unconscious activities like breathing and your heart rate
48
what do scanners do
investigate brain function
49
what does a CT scan do
uses X-Rays to produce an image of the brain
50
what does the CT scan show
it shows the main structure of the brain, however does not show the functions
51
what does a PET scan do
uses radioactive chemicals to shows which parts of the brain are active when the person is inside the scanner
they are detailed
52
what does the PET scanner show
both the structure and function of the brain in real time, can study disorders (Alzheimer’s)
53
3 problems when treating the CNS
1. hard to repair damage - don’t repair themselves
2. not easy to access - not possible to remove surgically certain places
3. problems can lead to permanent damage - surgery could damage further
54
order and explanation of the response of the CNS
1. nervous system is made up of neurones
2. sensory detectors sense a change in your environment
3. stimulus is detected by receptors, info is then converted to a nervous electrical impulse and sent along sensory neurones to the CNS
4. the CNS coordinates the response, impulses travel through the CNS along relay neurones
5. the CNS sends info to an effector along a motor neurone, the effector responds accordingly
6. the time it takes you to respond to a stimulus is called your reaction time
55
what do neurones do
transmits information rapidly as electrical impulses
56
neurones facts
- cell body with nucleus (plus cytoplasm and sub cellular structures)
- very long (speeds up the impulse)
- has extensions to connect other neurones
57
what do dendrites and dendrons do
carry nerve impulses towards the cell body
58
what do axons do
carry nerve impulses away from the cell body
59
what are axons surrounded by
myelin sheath
60
sensory neurones facts
- one long dendron carries nerve impulses from receptor cells to the cell body, located in the middle of the neurone
- one short axon carries nerve impulses from the cell body to the CNS
61
motor neurone factors
- many short dendrites carry nerve impulses from the CNS to the cell body
- one long axon carries nerve impulses from the cell body to effector cells
62
relay neurone factors
- many short dendrites carry nerve impulses from sensory neurones to the cell body
- an axon carries nerve impulses from the cell body to motor neurones
63
what is the connect between two neurones is called a
synapse
64
how is the nerve signal transferred
by chemicals called neurotransmitters, which diffuse across the gap
65
step by step how do reflexes prevent an injury
1. reflexes are automatic, rapid responses to stimuli - reduce chance of being injured
2. the passage of info in a reflex (from receptor to effector) is called a reflex arc
3. the neurones in a reflex arc go through the spinal cord or unconscious part of the brain
4. when a stimulus is detected by receptors, impulses are set along a sensory neurone to relay neurones in the CNS
5. when the impulses reach a synapse between the relay neurone and motor neurone, the same thing happens - neurotransmitters are released and cause impulses to be sent along a motor neurone
6. When the impulses reach a synapse between the relay neurone and a motor neurone, the same thing happens. Neurotransmitters are released and cause impulses to be sent along the motor neurone.
7. The impulses then travel along the motor neurone to the effector (in this example it's a muscle, but it could be a gland).
8. The muscle then contracts and moves your hand away
9. as you don’t have to spend time thinking about the response, it’s quicker than normal responses
66
what does the cornea do
refracts and bends light into the eye
67
what does the iris do
controls how much light enters the pupil
also refracts light, focusing into the retina
68
what does the retina do
light sensitive part which is covered in receptor cells called rods and cones (detect light)
69
what are rods
more sensitive in dim lights but can’t sense colour
70
what are cones
cones are sensitive to colours but not so good in dim light
71
what does the optic nerve do
carries these impulses from the receptor to the brain
72
what is longsightedness
unable to focus on near objects
occurs when lens is wrong shape and doesn’t bend light enough or the eyeball is to short
73
what is shortsightedness
people cannot focus distant objects
occurs when lens is wrong shape and bends light too much or the eyeball is too long
74
how to fix longsightness
convex lens
75
how to fix shortsightness
concave lens
76
what is colourblind
can’t tell the difference between certain colours
77
what is a cataract
cloudy patch on the lens, stops lights entering normally
