Membranes and Membrane Proteins Lecture

2/4/26

semi-permeable

membranes serve as ____________ barriers for cells

semi-permeable

__________ means some things pass through while others cannot

proteins

membranes have both lipids in them as well as _____-

concentration gradient

a ____________ is a different in concentration across a membrane

false

T or F: ions will always pass through a membrane

passive transport

_____________ is the movement of substances down their concentration gradient without adding energy

osmosis

_________ is movement of water across a membrane to reduce a concentration gradient

shrivel up

high salt outside of animal cells cause them to _____________

burst

low salt outside of animal cells cause them to _______ if too low.

rotation

_______ is spinning of a lipid in place

lateral diffusion

______________ is movement in a plane

transverse diffusion

__________ is changing sides of a membrane

easily

do unsaturated fatty acids move easily or slowly?

slowly

saturated fatty acids pack tightly in a membrane which makes them to move ______- (easily or slowly)?

signaling, enzymes, transporters, cell-cell recognition, and binding junctions

membrane proteins serve 5 specific functions:

glycoproteins

______ are proteins with carbohydrates attached to them)

integral

______ membrane proteins are embeded in bilayer and may cross it

peripheral

_________ membrane proteins bind non-covalently to one side

lipid anchored

_____________ proteins are covalently bound to lipids

4

integral membranes proteins come in ___ major kinds

receptrors, channels, transporters, resident

the 4 major kinds of integral membrane proteins are membrane ______…

receptors

membrane _________ transmit info only into the cell

signal transduction

membrane receptors use _______ to move info from the membrane to the nucleus

protein channels

______________ allow small molecules and ions to pass through the membrane but always moving down their concentration gradient used mostly for ions, often in nervous system or muscles

protein transporters

____________are used to move molecules like sugars, amino acids, wastes, and some key ions through the cell membrane

protein transporters

___________ bind to particular molecules (ie. susbtrates) and physically change shape to move things across the membrane may be active (energy required) or passive transporters

active

______ energy requires energy

membrane resident proteins

________________— bind to the membrane but may be there for structural reasons or to help other molecules function

resident

membrane _______ proteins often hold cytoskeleton or enzymes to the membrane of the surface

peripheral membrane proteins

_____________ bind to a membrane only on one side and may bind to other membrane proteins or hydrophilic lipid heads

peripheral

many _______ membrane proteins serve as regulators and signaling proteins of receptors

lipid linked

___________ proteins do not attach to the membranes by themselves, but use a lipid ‘tail"‘ that is covalently bound to the protein