Please enable JavaScript.
Coggle requires JavaScript to display documents.
transporting substances across membranes - Coggle Diagram
transporting substances across membranes
active transport
active transport is the movement of molecules and ions through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration
active transport requires carrier proteins
each carrier protein being specific for a particular type of molecule or ion
although facilitated diffusion also uses carrier proteins active transport is different as it requires energy
the energy is needed to make the carrier proteins change shape allowing it to transfer the molecules or ions across the membrane
the energy which is required is provided by ATP (adenosine triphosphate) produced during respiration
ATP is hydrolised to release energy
importance of active transport
reabsorption of useful molecules and ions into the blood after filtration into the kidney tubules
the absorption of some products of digestion from digestive tract
the loading of sugar from photosynthesising cells of leaves into the phloem tissue for transport around the plant
the loading of inorganic ions from the soil into root hairs
bulk transport
it is another form of active transport
large molecules e.g. enzymes, hormones and bacteria are to large to move through carrier and chanel proteins so the move in and out of cells by bulk transport
endocytosis- the bulk transport of material into cells --. two types phagocytosis (solids) and pinocytosis (liquids)
the process is the same for both. the cell surface membrane fist invaginates when it comes into contact with the material and then it enfolds the material until eventually the membrane fuses forming a vesicle, the vesicle pinches off and moves into the cytoplasm to transfer the material for further processing within the cell
exocytosis
vesicles ussually formed by the golgi apparatus move towards and fuses with the cell surface membrane, contents of the vesicle are then released outside the cell