Biology

Biology

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B3I - Cloning
Plant and Animal Cells:
Animal Cells
o Nucleus, cell membrane, cytoplasm, mitochondria (where
respiration takes place)
Plant Cells
o Nucleus, Cell membrane, cell wall, cytoplasm,
chloroplasts, mitochondria
Respiration
o Turns glucose into energy and oxygen into water and
carbon dioxide, and releases energy.
Nucleus contains DNA:
Double stranded helix has lots of groups called nucleotides
Each nucleotide has a base : A, T, C, G
A matches with T, C matches with G ­ called complementary
base- pairing
DNA replication:
DNA copies itself every time a cell divides, so it still has the
same amount of DNA
To copy, it has to divide the double helix and then each
nucleotide joins onto a matching base.
Fingerprinting:
Isolation - separate the DNA from other tissues
Fragmentation - use an enzyme to break the DNA into short
lengths
Separation - pass an electric current across a layer of gel
which has the DNA fragments at one end. The fragments will
move different distances across the gel. This is called gel
electrophoresis
Comparison - match the pattern of fragments on the gel with
other samples of DNA

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B3I - Cloning
Proteins are made by DNA:
Proteins are made up from strands of amino acids
Each amino acid is made from 3 bases
Proteins are made from 20 different amino acids
How they work:
Enzymes are soluble protein molecules which speed reactions in
the body ­ biological catalysts
Each enzyme will only speed up one reaction because the
shape of the enzyme molecule needs to match the shape of the
molecule it reacts with (the substrate molecule).…read more

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B3I - Cloning
Some enzymes, such as those used in digestion, are adapted
to work faster in unusual pH conditions and may have an
optimum pH of 2 (very acidic) if they act in the stomach.…read more

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B3I - Cloning
DIFFUSION IS THE PASSIVE MOVEMENT OF PARTICLES FORM AN AREA
OF HIGHER CONCENTRATION TO AN AREA OF LOWER CONCENTRATION
Speeding up diffusion:
Particles move faster, eg when they're warmer
concentration difference is greater, eg by replacing air in the
lungs with fresh air rich in oxygen
distance for diffusion is kept to a minimum, eg by having a thin
layer of cells lining the lungs
the surface area for diffusion is increased eg by folding
Diffusion in...…read more

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B3I - Cloning
Blood cells
Red blood cells transport oxygen.
White blood cells protect against disease.
Blood platelets help the blood to clot.
Red blood cells
These carry oxygen from the lungs to tissues.
The cells are tiny to allow them to pass through narrow
capillaries
They are biconcave shape for increased surface area
They contain haemoglobin which absorbs oxygen in the lungs
and releases oxygen in the rest of the body
Haemoglobin absorbs oxygen to form bright red
oxyhaemoglobin in oxygen rich environments.…read more

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B3I - Cloning
Our Blood Circulation:
Mammals have a double circulatory system ­ oxygenated blood
pumped around body at the same time deoxygenated blood
does.
Fish don't have double circulatory systems
Blood is oxygenated in the lungs, then goes to the heart where
it is pumped around the whole body, then becomes
deoxygenated and enters the veins which go back to the heart
and then to the lungs.…read more

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B3I - Cloning
The semi-lunar, tricuspid and bicuspid valves prevent backflow
The atria (plural of atrium) exert less pressure than the
ventricles so they have a thinner muscular wall.…read more

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B3I - Cloning
Mitosis
Mitosis is the type of cell division used for growth and repair.
It creates 2 new cells from one
In mitosis each chromosome is copied exactly.
The new chromosomes are moved to opposite sides of the cell,
before the cell divides leaving one complete set of 46
chromosomes in each of the two new cells.
Constant cell division ensures that cells never get too large.…read more

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B3I - Cloning
The type of cell division that produces gametes with half the
normal chromosome number is called meiosis.
Gametes contain different genetic information to each other
and to the parent cell.
Meiosis is responsible for causing genetic variation.…read more

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B3I - Cloning
o Childhood ­ Development of brain
o Adolescence ­ Completion of body development
o Maturity ­ Cell division for growth stops
o Old Age ­ No growth
The head grows slower than the rest of the body, if the head is
growing too slowly, or is too small or big then is can alert
possible problems.…read more

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