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Biology > SB2 - Cells And Control > Flashcards

SB2 - Cells And Control Flashcards

1
Q

What’s the cell cycle

A

A process to repair and require new cells for growth

Make new cells

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2
Q

How many chromosomes do human body cells have

A

23 pairs and 46 in total

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3
Q

What are cells with 2 sets of chromosomes called

A

Diploid

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4
Q

What are haploid cells

Give me an example too

A

When a cell contains only 1 copy of each chromosome

Gametes are haploid (sex cells)

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5
Q

How many phases are in the cell cycle

A

2

Interphase and mitosis

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6
Q

Tell me about the interphase

A

Cell makes extra sub cellular cell parts eg mitochondria. DNA replication also occurs

Copies of chromosomes are made, copies stay attached to eachother and look like X’s

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7
Q

Tell me about mitosis

A

The second stage in the cell cycle

Cell splits to form 2 daughter which are identical to parent cell

It occurs in a series of stages

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8
Q

Tell me about the prophase

A

Nucleus starts to break down and spindle fibres appear

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9
Q

Tell me about the metaphase

A

The chromosomes are lined up on the spindle fibres accross the middle of the cell

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10
Q

Tell me about the anaphase

A

The chromosome copies are separated and moved to either end of the cell on the spindle fibres

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11
Q

Tell me about the telophase

A

A membrane forms around each set of chromosomes to form nuclei

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12
Q

Tell me about cytokinesis

A

A cell surface membrane forms to separate the 2 cells during cytokinesis

Cell walls form in plant cells

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13
Q

What’s asexual reproduction

A

Some organism can reproduce with just one parent

They produce clones

Relies on mitosis

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14
Q

What are clones

A

Means their cells have the same chromosomes as parent (genetically identical)

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15
Q

Which is faster sexual or asexual reproduction

A

Asexual Becuase organisms do not need others

Though sexual produces variation

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16
Q

What are cancer cells

A

Sometimes cells turn in to cancer cells and undergo uncontrollable division

Rapid division lead to growing link or tumours that c an damage body and result in death

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17
Q

What is growth

A

An increase in size as a result of an increase in number or size of cells

Cell number increased due to division by mitosis

Can be recorded by taking measurements over time, such as length or mass

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18
Q

What’s a percentile

A

For example 25% of babies will have masses below the 25th percentile so 75% will be below the 75th percentile line

So if the 25th percentile for an 8 month baby is 8kg then 25% of 8 month old babies have a mass below this value

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19
Q

What’s differentiation

A

A process that changes less specialised cell into more specialised ones

Then adapt to a new function

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20
Q

How is a red blood cell adapted

A

It has not nucleus so there’s more space for red haemoglobin molecules which carry oxygen

Also has a large surface area which allows oxygen to diffuse in and out more quickly

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21
Q

How are fat cells adapted

A

The cytoplasm is filled with large fat droplets

The fat is stored until
The body needs more energy

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22
Q

How are neurones adapted

A

Have a long fibre that carries electrical impulses around the body and many connections to other neurones

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23
Q

How are muscle cells specialised

A

Contain special contractile proteins that can shorten the cell

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24
Q

What are meristems

A

A group of cells near the end of each shoot and root that allows the plant to continue growing throughout their lives

The cells in meristems divide rapidly by mitosis

Many of these cells increase in length (elongation) and differentiate

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25
Tell me some examples of specialised plant cells
Root hair cells Xylem cells
26
How is a xylem vessel made What's it like
From dead xylem cells It has a thickened wall to withstand water pressure Tiny pores in wall allow water and mineral salts to enter and leave the vessel There's no cytoplasm so vessel is empty Loses cell walls to form a tube
27
How can you measure the percentage changes of growth in plants
Final value - starting value divided by the starting value X 100%
28
What are stem cells
Cells that divide repeatedly over a long period of time to produce cells that then differentiate
29
Where are stem cells found in plants
Meristems (roots and shoots)
30
What are plant stem cells like
Usually able to produce any kind of specialised cell throughout their life Not like most animals especially vertebrates
31
What are embryonic stem cells
The cells of an early stage embryo They can produce into any type of specialised cell As the cells starts to divide the embryo starts to develop different areas that will become different organs The stem cells in these areas become more limited in the types of specialised cell they can produce
32
What are adult stem cells
When an animal is fully developed the stem cells usually only produce one type of specialised cell that is in the tissue around them They allow tissues to grow and replace old or damaged cells
33
What else can stem cells be used for
Treating diseases caused by damaged cells Scientists studied to use adult and embryonic stem cells to treat diseases such as type 1 diabetes or to replace damaged cells This is done by stimulating stem cell to make them produce the specialised cells that are needed them injecting them where needed
34
What are some of the problems with using stem cells
If stem cells continue to divide inside body after being replaced they can cause cancer stem cells from one person are often killed by the immune system of other people that are put into - called rejection
35
Where is the cerebral cortext
It's divided into 2 cerebral hemispheres at the front of the brain
36
Where's the cerebellum
Under the back of the brain near the spinal cord
37
What's the cerebral cortex
Makes up 80% of brain Used for most of our senses, language, memory, behaviour and consciousness Divided into 2 cerebral hemispheres
38
What does the right hemisphere do
It communicates with the left side of the body RIGHT Hemisphere communicate with the LEFT side of body
39
What does the left hemisphere do
Communicates with the right side of body
40
Tell me about the cerebellum
The base of the brain, the area is divided into 2 halves and controls bosh and posture Coordinates the timing and fine control of muscle activity making sure movements are smooth
41
What's the medulla oblongata
Controls your heart rate and breathing rate Responsible for reflexes such as vomiting, sneezing and swallowing
42
What's the spinal cord
The neurones that comedy to the medulla oblongata connect to the spinal cord It's about the width of a finger and consists of many nerves to carry info between the brain and rest of body
43
What are neurones
Bundles of neurones
44
In brain surgery what can electrodes be used for
Apply electrical currents to the brain If patients are awake they can be asked what they feel A current may also make the patient do something or stop an action occurring This allows the functions of the brain to be investigated
45
What does scanning allow us to do
Look deeper into the brain than surgery does Allows the study of healthy individuals without risk of damaging brain
46
What does a CT shape show
Shows the shapes of structures in the brain An X-ray bean moves in a circle around the head and detectors measure the absorption of the X-rays A computer used this to build a view of inside the body as a series of "slices" differences in the shapes in the brain can be linked to the function of those parts
47
What's a PET scan
Shows brain activity as the patient is injected with radioactive glucose Most active cells take in glucose than less active ones (for respiration) the radioactive atoms cause gamma rays which the dabbed defects The more gamma rays coming from a certain area contain more active cells
48
What can spinal cord damage do
Reduces the flow of information between the brain and parts of the body Nerve damage in the lower spinal cord can cause loss of feeling and use of legs
49
What's quadriplegia
Damage of the spinal cord in the neck can cause loss of use of both arms and legs
50
Are there any cures for spinal cord damage
No adult stem cells can differentiate into neurones in spinal cord so no new neurones cannot be made to repair damage Wires can be used to stimulate nerves and muscles below the damage but patients do not regain full movement of feeling Treatments using stem injections are being developed
51
What's a brain tumour
When cancer cells often divide rapidly to form a tumour
52
What are the effects of a brain tumour
May squash parts of the brain and stop them working
53
How can brain tumours be treated using radiotherapy
Tumours can be cut or killed using radiotherapy (high energy X Ray beams) Can damage body and brain
54
Who can chemotherapy be used to treat s brain tumour
Injecting drugs that kill actively dividing cells Can damage body and brain
55
Why Might chemotherapy not work
Due to the blood- brain farrier (a natural filter that only allows certain substances to get from the blood into the brain mainly due to fells in capillary walls fitting very close together So chemicals won't enter to kill cells
56
How can scientists study how the brain works
By growing brain tissue in a lab using stem cell techniques
57
What's the vertebra
24 bones form the backbone to protect spinal cord
58
What's the sciatic nerve
The thickest nerve that connects to the heal of the spinal cord
59
What is the central nervous system
(CNS) and it'd the brain and spinal cord which controls your body Nerves make up the rest of Your nervous system - allows the parts of your body to communicate using electrical signals called impulses
60
What's a stimulus
Anything your body is sensitive to including inside your body and your surroundings
61
Give me some examples of sense organs
Eyes, ears, skin
62
What detect stimuli
Sense organs that contain receptor cells Eg. Skin contains receptor cells that detect the stimulus of temperature change
63
How do receptor cells crest a response
Receptor cells crest impulses which usually travel to the brain, the brain processes this information and can send impulses to the other parts of the body to cause something to happen (a response)
64
What's neurotransmission
The travelling or transmission of impulses Happens in neurones
65
What's a sensory neurone (there are different types) How does neurotransmission happen
It's function is to carry impulses from receptor cells towards the CNS A receptor cells impulse passes into a tiny branch Called a DENDRITE Then it's transmitted along the DENDRON and AXON A series of axon terminals allows impulses go be transmitted to other neurones
66
What are dendrons and axons like(how are they adapted)
Frequently long to allow fast nuerotransmission over long distances Also have a fatty layer surrounding these parts called the myelin sheath - is electrically insulates a neurone from neighbouring neurones, stopping the signal Losing energy May also make an impulse jump along the cell between gaps in the myelin and so speed up neurotransmission
67
What do dendrites do
Receive impulses from receptor cells
68
What do axons do
Pass impulses on to other neurones
69
Where in the eye does it contain receptors
The retina - the back of the eye
70
What are cones
Receptor cells that are sensitive to the colour of light. Some cones detect red light while others detect green or blue They generate impulses in sensory neurones that lead into the brain through the optic nerve The information from all the cones is processed into full colour vision in the cerebral hemispheres
71
What are rods
Receptor cells that detect differences in light intensity not colour Rods work well in very dim light whereas cones only work in very bright light
72
What's the iris
The coloured part of the eye, the amount of light entering the eye is controlled by muscles in the iris Which can constrict the pupil (decrease diameter) or dilate it (make it bigger) Bright light can damage receptor cells in the retina
73
What's the cornea
Clear colourless covering over eye that focuses light, It refracts light to bring them together
74
Where's the pupil
The dark area in the middle of the eye where light enters
75
What are the ciliary muscles
They make the lens fatter to focus light from near objects and thinner to focus light from distant objects
76
What's the lens
It fine tuned the dividing to produce a very clear image
77
What's being short sighted like
Distant objects appear blurred There are 2 reasons The eyeball is too long The cornea is too curved and bends the Rays more than is should Longsighted is the opposite
78
How can we fix short and long sightedness
Contact lenses or glasses of a laser can be used to cut away some of the cornea and reshape it
79
What's a cataract
Sometimes a protein builds up inside the lens to make it cloudy It can be restored by replacing the clouded lens with a plastic one
80
How is colour blindness caused
Due to some cones not working properly - the most common is red-green colour blindness in which the cones that detect green of it are faulty so it's difficult to tell apart It can't be corrected
81
What are the effectors
They carry out at action When a brain coordinates a response to a stimulus impulses are sent to the effectors They include muscles and glands
82
What are motor neurones
They carry impulses to effectors No DENDRON, dendrites on the cell body
83
What are relay neurones
They are short neurones that are found in spinal cord, they link motor and sensory neurones Also make up a lot of nerve tissue in brain No DENDRON Dendrites are on the cell body
84
What's a synapse
It contains a tiny gap when an impulse reaches an axon terminal, a neurotransmitter substance is released into the gap, it's detected by the next neurone which generates a new impulses Synapses slow down neurotransmission by are useful becuase neurotransmitters are only released from axon terminals and so impulses flow in one direction Also allows many fresh impulses to be generated in many neurones connected to one neurone - the originals impulse does not less to be split and lose strength
85
What's a reflex
Reflex actions are responses that are automatic and extremely quick to protect the body They use neurone pathways called reflex arcs which bypass the parts of the brain involved in processing information and so are quicker than responses that need processing
86
Tell me the order of a response
``` Stimulus Receptor Sensory neurone Relay neurone Motor neurone Response ```

Biology (12 decks)

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