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cell organelles and its functions

nucleus- contains genetic materials, controls activities of the cell, produces ribosomes and ribonucleic acid (RNA)

Rough Endoplasmic Reticulum (rough ER)- transporting the newly protein synthesised, involve in synthesis of protein.

Smooth ER- tansports lipids and glycerol, synthesis lipids and non-protein substances

Mitochondria- site of cellular respiration which is areobic respiration, produce ATP >> adenosine triphosphate

ribosomes- site of synthesis of protein

golgi apparatus - site of production of enzyme and lysosome, storing carbohydrates and lipids, transports lipids

chloroplast - contain chlorophyll, site for photosynthesis

lysosomes - breaks down food and unwanted materials

cell membrane- regulates what passes into and out of cell.




DIFUSSION - net movements of solutes from a region of higher concentration to lower concentration,no energy required. the rate of diffusion depends on the concentration gradient, the distance takes place, the area takes place, the size of molecule.

facilitated diffusion - movements of solutes across a membrane with the help of tansport proteins

carrier protein - binds to the molecules they wan to transport and change their shape,and release the molecules on the other side.

protein channels- difussion of charged particles


OSMOSIS - passive mobement of water across a semi permeable membrane

ACTIVE TRANSPORT - molecules are moved across a lining membrane from a area of low concentraion to a high concentration. involves use of ATP and carrier protein.







IMPORTANCE OF WATER

- universal solvent, lubricant in joints - because it is a polar compound

- low viscocity, due to small size of molecule and hydrogen bonding that is easily broken. it enables blood plasma and lymph to flow easily. low viscocity makes a good lubricant in joints

-high specific heat capacity -due to large amount of enery is needed to break up hydrogen bonds. >> we can maintain a constant body temperature.

-usually high latent heat of fusion and evaporation. due to hydrogen bonding between water molecules, it is hard for water to separate and vaporise.

-water is densest at 4 degree celcius. >> helps in prevent oranisms from freezing to death.