Cells And Control Flashcards
What is the cell cycle?
A process of grown and repair for multicellular organisms
What does diploid mean?
Means it has two sets of chromosomes
What does haploid mean?
1 set of chromosomes
What are the two phases in the cell cycle?
Interphase and DNA replication
What occurs in the cell cycle after DNA replication?
Mitosis
What is interphase?
The cell make sub-cellular cell parts (mitochondria), DNA replication occurs, chromosomes in thread like chromatin, intact nuclear membrane
What happens in prophase?
The nucleus starts to break down and spindle fibres appear
What happens in metaphase?
The chromosomes are lined up on the spindle fibres across the middle of the cell (poles)
What happens in anaphase?
The chromosome copies are separated and moved to either end of the cell on the spindle fibres, (spindle fibres attach to the centromeres, pulling the chromatids apart)
What happens in telophase?
Spindle fibres disintegrate, and a membrane forms around each set of chromosomes to form nuclei
What happens in cytokinesis?
Two genetically identical diploid cells are formed
What is it called when organisms can reproduce using one parent?
Asexual reproduction
What is asexual reproduction?
It produces off springs from one parent that are clones, (they are genetically identical)
What does asexual reproduction rely on?
Mitosis
What are cancer cells?
Uncontrollable cell division. This rapid devision produces growing lumps of cell called tumours
Define growth and how can it be recorded
It’s an increase in size as a result of an increase in number or size. Growth can be due to cell division or mitosis, it can be recorded in length or mass
What is a percentile chart?
It’s a chart to record values and percentages, e.g measuring a baby’s weight compared to other babies
Go to page 32 and look at percentile chart
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What is the process that changes less specialised cells into specialised cells?
Differentiation
Go to page 33 and look a differentiation
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What are stem cells?
Cells that can divide repeatedly over a long period of time to produce cells that then differentiate
In plants what are stem cells found in?
Meristems
What are plant stems cells usually able to do?
Produce plant stem cells throughout its life
What are embryonic stem cells?
Cells of an early-stage embryo that can produce any type of specialised cell
What happens to the embryonic stem cells as the cells continue to divide?
The embryo starts to develop different areas that will become the different organs. The stem cells in these areas become more limited in the types of specialised cell they can produce
What are adult stem cells?
Cells that can only produce one type of specialised cell
What do adult stem cells allow?
The tissues to grow and replace old or damaged cells
How do doctors use adult and embryonic stem cells to treat diseases ?
This is done by stimulating stem cells to make them produce the specialised cells that are needed and then injecting them into the places they are needed
What is the problem with using stem cells?
If stem cells continue to divide inside the body after they have replaced damaged cells, they can cause cancer. Another problem is
that stem cells from one person are often killed by the immune system of other people that they are put into. This is called rejection
During brain surgery what can the electrodes do?
Apply electrical currents to the brain
What does scanning allow scientists to do?
Look deeper into the brain than surgery does, also it allows the study of a healthy individual without the risk of damaging the brain
Go to page 38 and 39 and look at the brain diagrams
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What does embryonic stem cells in a human embryo do?
Divides to produce more and more stem cells
In an embryo when do stem cells in the brain starts to differentiate to produce neurones?
3 weeks old
How many neurones does an adult brain have?
86 billion which interconnect with one another and other parts of the body to process information and control the body
What is the cerebral cortex?
It makes up 80% of the brain, it’s used for most of our senses, language, memory, behaviour and consciousness (our inner though and feelings). It’s divided into two cerebral hemispheres, each with slightly different functions. The right hemisphere communicates with the left side of the body and vice versa
In order to stay alive, what do all living things have to do?
Grow and repair itself
Go to page 39
Look at the diagram
Where in the brain is the cerebellum?
It’s at the base of the brain
What is the cerebellum?
It’s divided into two halves and controls balance and posture. It also coordinates the timing and fine control of muscle activity, making sure that movements are smooth
What does the medulla oblobgata do?
It controls your heat rate and your breathing rate. It is also responsible for reflexes rich as vomiting, sneezing and swallowing
What connects the brain to the spinal chord?
The mass of neurones that make up the medulla oblobgata connects these
What do nerves (a bundle of neurones) do?
Carry information between the brain and the rest of the body
What is a CT scan?
It shows the shape and structures in the brain
How do CT scans work?
X-Ray beams move in a circle around the head and detectors measure the absorption of the X-rays. A computer uses this information to build up a view of the inside of the body as a series of ‘slices’.
What can differences in the shape of the brain be linked to?
Linked to differences in the way people think and act, suggesting the functions of those parts
What does a PET scan do?
It shows brain activity
How does a PET scan work?
The patient is injected with radioactive glucose. More active cells take in more glucose than less active ones (for respiration). The radioactive atoms cause gamma rays, which the scanner detects. More gamma rays come from parts containing more active cells
What can carrying out activities during a PET scan cause?
It causes specific areas of the brain to become more active
What happens if you damage your spinal chord?
It reduces the flow of information between the brain and parts of the body. Nerve damage in the lower spinal chord can cause loss of feeling in, and use of the legs
What can damage in the neck cause?
Quadriplegia (loss of use of both arms and legs)
Why can’t new neurones be made to repair damage?
Because there are no adult stem cells that can differentiate into neurones in the spinal chord. However wires can be used to stimulate nerves and muscles below the damage but patients do not regain full movement or feeling
What can a brain tumour do?
It can squash many parts of the brain and stop them working
How can we get rid of brain tumours?
They can be cut out, or the cells can be killed using radiotherapy (high energy X-Ray beams) and chemotherapy (injecting drugs that kill actively dividing cells.
What can happen when you teat cancer with the different methods
They may damage the brain (and body) and chemotherapy might not work in the brain due to the blood-brain-barrier, which is a natural filter that only allows certain substances to get from the blood into the brain (mainly due to the cells in the capillary walls in the brain closely fitting together)
To study how the brain works, what can be useful to scientists?
To experiment on living tissue, it cannot be done with living people, but in 2015 scientists managed to regrow Brian tissue in their lab by using stem cell techniques
What controls your body?
The brain and the spinal chord which form the central nervous system (CNS) and nerves make up the rest of the CNS
What does the nervous system allow ?
This or gain system allows all the parts of your body to communicate, using electrical impulses
What is a stimulus?
Anything in your body is entities to including changes in your body and the surroundings
What are receptor cells?
Sense organs that detect stimuli
What do receptor cells do?
They create impulses which usually travel to the brain. The brain then processes this information and can send impulses to other parts of the body to cause so,etching to happen (a response)
What is neurotransmission?
The travelling or transmission and happens in neurones (nerve cells). Neurones have a cell body and long extensions to carry impulses
There are different types of neurone but what are sensory neurones?
It’s function is to carry impulses from receptor cells towards the CNS
What does a receptor cell impulses pass onto?
A tiny branch called a dendrite, it is then transmitted along the de drop and the axon, a series of axon terminals allow impulses to be transmitted to other neurones
Why are dendrons and axons frequently long?
To allow fast neurotransmission over long distances
What is the myelin sheath?
The fatty layer surrounding dendrons and axons
What does the myelin sheath do?
This electrically insulates a neurone from neighbouring neurones, stopping the signal losing energy, it also makes an impulses jump along the cell between the gaps in the myelin and so speeds up neurotransmission
What is the eye?
It’s a sense organ that contains receptor cells found in a layer called the retina
What are cones? (Light)
They are receptor cells that are sensitive to the colour of light, some cones detect red light while other detect green or blue.
What do cones do?(eye)
They generate impulses in sensory neurones, which lead into the brain through the optic nerve. The information from all the cones is princesses into full colour vision at the back of the cerebral hemispheres
What are rods? (Eye)
Rods are receptor cells that detect differences in light intensity, not colour. Rods work well in very dim light whereas comes only work in bright light, which is why your colour vision is poor in dim light
What do ciliary muscles do?
Alter the shape of the lens
What is the retina?
A layer of rods and cones
What is the cornea?
Clear, colourless covering that focuses light
What is the iris?
The coloured part of the eye
What does information from the cones do?
Information from the cones are combined in the brain to produce all the colours, information from the rods is processed as shades of dark and light
What’s the optic nerve?
Contains bundles of neurones
What is the pupil?
It’s where light enters
What is the iris?
The muscles control the amount of light going in, which can constrict the pupil, or dilate it, bright light can damage the receptor cells in the retina
What do light rays entering the eye need to focus on?
Focus onto a point in the retina to produce a clear image
In the eye what is most of the focusing done by?
The cornea, which bends light rats to bring them together, the lens then fine-tunes the focusing, ciliary muscles make the lens fatter to ficus light from near objects and thinner to focus light from distant objects
For short sighted people why do distant objects appear blurred?
This is because the rays of light from the distant objects are focused in front of the retina. There are two possible reasons for this: the eyeball or too long or the cornea is too curved and bends the rays more than it should, long sightedness is caused by the opposite problems
How do you correct shortsightedness?
With a diverging lens
How do you correct longsightedness?
With a converging lens
What is a cataract?
When a protein builds up inside the lens and makes it cloudy, full visions van be restored by replacing the clouded lens with a plastic one
What happens for colour blindness?.
People with colour blindness have some comes that do not work properly and so have difficulty in seeing some colours. Colour blindness cannot be corrected
What happens when the brain coordinates a response tot the stimulus?
Impulses are sent t the effectors and these carry out an action. Effectors include muscles and glands
What are motor neurones?
They carry impulses to the effectors
What are relay neurones?
They are short neurones that are found in the spinal chord, where they link motor and sensory neurones. They also make up a lot of the nerve tissue in the brain.
What do dendrites do?
Receive impulses from othe neurones
What do axon terminals do?
Pass impulses to effector cells
When does one neurone meet another?
At a synapse, which contains a tint gap
What happens when an impulses reaches an axon terminal?
A neurotransmitter substance is released into the tiny gap , this is detected by the next neurone, which generates a new impulses. Synapses slow down neurotransmission. Hey are however useful because neurotransmitters are only released from the axon terminals and so impulses only flow in one direction. They also allow many fresh impulses to be generated in many neurones connected to one neurone - the original impulses does not need to be split and lose strength
What are reflex actions..
They are responses that are automatic, extremely quick and protect the body. They use neurone pathways called reflex arcs, which by
Ass the parts of the brain involved in processing information and so are quicker than responses that need processing
Where do impulses go?(reflex arcs)
From the motor neurone pass into the muscle cell (the effectors) via synapses. The muscles then quickly move the part of the body away from the source of pain
What can receptor cells for pain in the skin cause?
Impulses to be transmitted in a sensory neurone
