topic 2.1.5: biological membranes Flashcards
what is the role of phospholipids in cell membranes?
form the bilayer
what is the role of cholesterol in cell membranes?
adds to hydrophobic barrier, increases thermal stability
what is the role of glycolipids and glycoproteins in cell membranes?
facilitate cellular recognition, form H bonds with water to strengthen membrane
what is the role of proteins in cell membranes?
transporting ions and molecules into and out of cell
describe the process of simple diffusion
net movement of particles from high to low conc, passive
small, non polar mols pass through cell membranes
describe the process of facilitated diffusion
involves either:
carrier proteins (mol attaches and protein changes shape to allow it through)
channel proteins (form pores in memb)
describe the role of carrier proteins in the process of active transport
mol binds to protein, ATP binds to protein, hydrolysis of ATP to ADP and phosphate causes protein to change shape and release mol, then release phosphate and return to og shape
describe the process of endocytosis
memb engulfs material to create vesicle, which moves into cytoplasm
what is the difference between phagocytosis and pinocytosis?
phagocytosis- uptake of solid materials
pinocytosis- uptake of liquid
describe the process of exocytosis
vesicles fuse with memb and materials released
what happens when an animal cell is in a hypotonic solution?
cell has lower water potential, so swells and bursts (cytolysis)
what happens when an animal cell is in a hypertonic solution?
cell has higher water potential so shrivels (crenation)
what happens when a plant cell is in a hypotonic solution?
cell has lower water potential so swells and becomes turgid
what happens when a plant cell is in a hypertonic solution?
cell has higher water potential so shrinks and becomes plasmolysed
