membranes - exam 1 Flashcards
transmembrane protein
protein that transects entire phospholipid bilayer
peripheral membrane protein
protein on the periphery of phospholipid bilayer
glycoprotein
portein w/ a carbohydrate (oligosaccharide) attached to it
oligosaccharides attached on the outside of the cell
membrane fluidity affected by temperature
body temp = bilayer is lfuid
as it gets warmer & melts = nonfucntional, no coming back
as it gets colder = slower, less fluid
solidifies = not permeable
membrane fluidity of unsaturated tails
remains fluid at lower temperatures
membrane fluidity of saturated tails
straight & packed together tightly, less movement
“freezes” faster
membrane fluidity affected by length of tails
longer tail = stronger hydrophobicinteractions = less fluid
membrane fluidity affected by cholesterol
high temp - reduces membrane fluidity
low temp - helps membrane stay fluid, inhibits packing of phospholipids
desaturase
enzyme that inserts a double bond into a fatty acid
makes it unsaturated
simple diffusion
movement down the concentration gradient
no proteins or energy needed
small, uncharged, hydrophobic molecules, gases, & H2O can pass through
large polar molecules & ions cannot
facilitated diffusion
movement down the concentration gradient
movement aided by proteins
no energy needed
channel proteins
pore-forming transmembrane proteins
many channels are gated - open & close in response to specific signals
selective
rapid response
carrier proteins
change shape during transport
selective
slower response - 1 at a time
good for sustained action
osmosis
movement down concentration gradient
hypotonic to hypertonic
proteins needed for rapid osmosis, but not passive
no energy needed
hypotonic
lower concentration of solute
higher concentration of water
hypertonic
higher concentration of solute
lower concentration of water
isotonic
same concentration of water
aquaporins
water channel proteins that facilitate rapid water movment
ATP
adenisone triphosphate
only moleculse w/ 3 phosphates
how ATP energy is created
ATP molecule –> hydrolysis
=
adenisone DIphosphate + 3rd phosphate = energy
active transport
movement against concentration gradient
low to high
proteins needed – pumps
energy needed
sodium potassium pump
picks up sodium
gets energy
changes shape & lets sodium go
picks up potassium
gets energy & changes shape
lets potassium go & picks up sodium
vesicular (bulk) transport
movement of substances into & out of the cell by vesicles (membrane bound sac)
phagocytosis
cell eating
“food” or other particle
big molecules
specialized cells
food vacuole
pinocytosis
cell drinking
ions, small soluble molecules
takes in everything & gets rid of what it doesn’t want
non-selective
receptor mediated endocytosis
highly selective, only wants one specific molecule
receptor: membrane protein w/ binding site that is specific shape for signal to bind
