unit 2, membranes Flashcards
what are cell surface membranes made out of
lipids , cholesterol
proteins attached to lipids
carbohydrates
what does amphipathic mean
hydrophobic and hydrophilic
how does the micelle form
the phospholipid tails are hydrophobic so shields in the middle and is protected by the hydrophilic phosphate group
what makes up the fluid mosaic model
phospholipids move , whilst proteins are dotted about
why is there an electrostatic attraction
because water is polar and the phosphate head it polar and negatively charges
what can pass through the partially permeable membrane
water , singular molecules because they are small enough
what is the sodium potassium pump
use of sodium to assist amino acids to a higher concentration as sodium is going down its concentration gradient whilst it carries the amino acids up
the sodium is doing passive diffusion
what is a carrier protein
•moves larger molecules across membrane and down a concentration gradient, the carries can change shape to fit
• helps diffusion and active transport
•spans the whole membrane , up/down
what is the channel protein
•allows ions and large molecules to pass through
•top to bottom of membrane, spans the whole of it
•active diffusion
how does cholesterol provide membrane stability
•binds to hydrophobic tail, to restrict movement of the bilayer , to maintain shape of a animal cells
•has hydrophobic regions to prevent substances passing through
what is a glycolipid
lipid and carbohydrate
what does the glycolipid do
maintains stability of membrane like cholesterol
cellular recognition, eg) immune response
form tissues (similar to glycoproteins)
what is cholesterol
a lipid
can some receptor proteins be glycoproteins
yes
what are receptor proteins
allows cells to detect chemicals and gives cell messages, eg) insulin instructs glucose to be absorbed
