Bulk/Active Transport endocytosis- envelops food particles • substances required for growth are sometimes too large to cross the bilayer • 3 main types • phagocytosis- enveloping particulate, organic matter • pinocytosis- enveloping liquid • receptor-mediated endocytosis- transfer of specific molecules o only food particles that fit attach to the receptor o clathrin - protein that coats the inner pit o each pit folds inward to form a vesicle • low-density lipoprotein - brings cholestrol into the cell to be used in the membranes exocytosis- reverse of endocytosis • discharges material from vesicles • used by plants to send material for cell wall construction through the membrane • used by animals to secrete hormones, neurotransmitters, enzymes, etc • protists use contractile vacuoles for exocytosis active transport- moves substance against the concentration gradient • powered by ATP • uses selective protein channels like facilitated diffusion • makes cells independent from environmental conditions
This is the end of the preview. Sign up
access the rest of the document.
This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.