specialised cells

• specialised cells are cells that have a specific function and are adapted to carry out that function
• specialised cells are differentiated to have different extra sub-cellular structures to suit their functions
• after cell is specialised, it's irreversable
• red blood cells - don't have nucleus - carry more oxygen
• red blood cells - bi-concave disc - larger surface area
• red blood cells - haemoglobin - binds with oxygen
• sperm cells - reproduction
• sperm cell - travel toward and fertilise the egg
• sperm cell - have half the full chromosome in the nucleus - the other half is in the egg
• sperm cell flagellum - swim
• sperm cells have many mitchondria to transfer energy to the tail
• acrosome (at the head of the sperm) - contain enzymes to break through the egg's outer layer
• sperm cell is streamlined - reduce usage of energy
• nerve cells - conduct electrical impulses for movement
• dendrites - connect with other cells
• axon - long, conduct electrical impulse in one direction
• myelin sheath - insulate the impulse
• synapses (at the end of the axon) - send neurotransmitter chemicals to another nerve cell or effector
• effector = muscle or gland
• nerve cells - long to cover more distance (increase the speed of transmission)
• cardiac & smooth muscle cells - involuntary contraction
• skeletal (striated/striped)muscle cells - cell run parallel fibres, voluntary contraction
• muscle cell special proteins - slide past each other making the muscle fibre to contract
• muscle cells have many mitochondria - transfer energy to the contraction (reaction to aerobic respiration)
• glycogen - store energy in form of glucose. broken down to release energy from glucose
• muscle cells are long to allow space to contract
• root hair cells locate in the soil to absorb water and mineral
• root hair cells have long hair like extension - increase surface area for absorbtion
• root hair cells have many mitochondria - fuel the active transport of minerals into the cell
• large vacuole - for water to move into by osmosis
• root hair cells have no chloroplast - no sunlight underground
• xylem cells transport water and minerals ions from the roots to the leaves
• xylem cells are made from dead cells
• xylem cell walls have broken down between - form hollow tubes, strengthened by lignin
• xylem cells use transpiration
• phloem cells transport glucose from the leaves to the rest of the plant
• phloem cells are made from living cells
• phloem cell walls have been broken down between cells to form sieve plates - allow sugars to flow freely by translocation
• companion cells (found either side of phloem cells) - contain many mitochondria to transfer energy to phloem cells
• phloem cells contain very few organelles for easy flows