smallest living organisms - single cells. can carry out all functions of life.
specialised cells - carry about a particular job, have specific function and structure
cell becomes specialised so its adapted to its job. look very different to typical plant/animal cell
examples: sperm, eggs, red blood cells and nerve cells.
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Fat Cells
if you eat more food than need - body makes fat, stores it in fat cells
helps us to survive when food - short supply
three main adaptations: small amounts - cytoplasm. lots of fat
few mitochondria - cell needs little energy
expand - 1000 times its original size - (fills with fat)
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Cone Cells (human eye)
light-sensitive layer of eye (retina) makes us see with colour
three main adaptations: outer segment has special chemical - changes chemically in coloured light. needs energy to change it to its original form.
middle segment packed with mitochondria. release the energy to reform visual pigment. lets us see continuously in colour.
final part: specialised synapse connects optical nerve. when coloured light makes visual pigment change - impulse is triggered. impulse crosses synapse travels along optic nerve to brain.
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Root hair Cells
find it near tips of growing roots.
Plants have to take in - water (lots) and dissolved mineral ions
root hair cells helps to take up water - efficiently
always close to xylem tissue
this carries water and dissolved ions to the rest of plant.
two main adaptations: root hairs increase surface area for water to move in cell
have large permanent vacuole speeds up movement by osmosis from soil across root hair cell
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Sperm Cells
released far away from egg that fertisile. contains genetic information from male.
need to move through water (animal) or female reproductive system to reach egg. have to break egg.
four main adapataions: long tail whips side-to-side helps move sperm.
middle section full of mitochondria - provides energy for tail
acrosome stores digestive enzymes - breaks down outer layers of egg
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