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B1: Cells (specialized cells (differentiate = when a cell becomes…
B1: Cells
specialized cells
differentiate = when a cell becomes specialized for a particular function and cannot change into different types of cell
sperm cell
structural point: has tail, packed with mitochondria for energy, head contains dna and enzyme
purpose: to swim towards the egg and break through egg membrane
function: to fertilize an egg
nerve cell
structural point: long, have branched connections
purpose: to connect to other nerve cells to create large network and to cover more distance
function: to pass, carry electrical impulses from the brain to the rest of the body
muscle cell
structural point: long, lots of mitochondria
purpose: to have space to contract, to generate the energy need for contraction
function: to contract quickly
root hair cell
structural point: big surface area, long hairs
purpose: absorb water and minerals from the soil
function: to collect water and minerals from the soil
xylem cell
structural point: hollow in the centre, long cells, joined end to end
purpose: so that substances can flow through them
function: transports water around the plant which is then evaporated by transpiration
phloem cell
structural point: very few sub cellular structure, long cells, joined end to end
purpose: so that substances can flow through them
function: to transport glucose/ sugar sucrose around the plant by translocation
Stem cells
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used for:
-making new rain cells to treat Parkinson's
-rebuilding bones and cartilage
-repairing damaged immune systems
-making replacement heart valves
Issues:
-embryo= potential for life
-relates to human cloning
-treatment does not always work
-alternative ways to culture cells
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therapeutic cloning= the use of cloning to produce new tissue from stem cells, for use in treatment of disease/ injury
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diffusion
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exanples
in animals
small intestine- digested food products from small intestine to the blood in the capillaries of villi
lungs- oxygen diffuses into the blood from air space to red blood cells and CO2 diffuses out from blood plasma to air space during respiration similar to gills
in plants
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leaves: oxygen, glucose and CO2 diffuse across the cell membrane during photosynthesis
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microscopy
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types of microscope
electron microscope: use electrons instead of light to form an image. Has higher magnification than light microscopes
light microscope:
use light and lenses to form a magnified image of a specimen. Allows us to see sub cellular structures
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Active transport
= the movement of molecules up a concentration gradient that requires energy from an area of high concentration to low
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cell division
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cell cycle
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interphase = when cells copy their dna to prepare for mitosis, spreads out dna and conducts dna checks/ other normal cell activites
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mitosis
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- pulls one copy of each chromosome to each side of cell
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