Lecture 13 Flashcards
primary lipid components of biomembranes
phosphoglycerides, sphingolipids, cholesterol
types of phosphoglycerides
PE, PC, PS, PI
sphingolipid is?
an amino alcohol with long hydrocarbon tail; example is glucosylcerebroside
Sterol characteristics (3)
nonpolar hydrocarbon tail; rigid, planar ring; polar hydroxyl group
cholesterol synthesis locale?
on ER (mainly in liver)
what motions can lipids have in a lipid bilayer
rotation, flexion, lateral diffusion; very RARELY you can get flip-flop
flipases do?
flip membrane lipids from one leaflet to another, this helps keep membranes asymmetric. synthesized at cytosolic face
Each bilipid membrane is the same (t/f)
false. they have cytosolic faces and exoplasmic faces
what is evenly distributed between inner and outer layer of bilayer?
cholesterol
membranes usually contain __ and ___
integral and peripheral membrane proteins
the peripheral membrane protein does not enter __
the hydrophobic core of bilayer
integral membrane protein features?
alpha helices that attract the fatty acyl side chains
what cell membrane proteins are distributed asymmetrically?
all transmembrane proteins (and glycolipids, even though thats not a protein)
where are carbohydrate chains attached to protein?
exoplasmic surface of protein
Long-chain lipids attach to ?
attach to gly or cys
glycophorin is major thing in?
membrane protein of erythrocytes in junctional complex, provides a negative charge on the cell
what do peripheral proteins do?
associate with integral membrane proteins; or, bind to phospholipid head groups
GCPR transmembrane receptors are involved in?
signaling, olfaction, and drugs
How do you tell the difference between peripheral and integral membrane proteins?
detergents will dissolve peripheral proteins below CMC; detergents will dissolve integral proteins at or above CMC by creating a micelle
microdomain is?
lipids that cluster together that are unique. aka liquid-ordered state
signal transduction proteins associate with
lipid rafts. if they exist.
what is FRAP? what can it see?
fluorescence recovery after photobleaching; usually antibody with tag that attaches to protein in plasma membrane. if you bleach one part of it, you can see lipid membrane diffusion. NOT ALL PROTEINS/LIPIDS DIFFUSE
Why are some lipids or proteins stationary in the lipid bilayer?
may attach to a receptor, internal cytoskeleton, or another cell interaction
spectrin heterodimers made of? associates with?
repeating subunits; associates with beta-subunit, N-terminus with actin (F-actin or actin filaments)
junctional complex is where??
spectrin molecule hub which attaches to little strands of actin filaments
Band 3: what does it associate with
It attaches to Spectrin INDIRECTLY, through ankryin
hereditary spherocytosis is a disease of ___
alpha and beta spectrin, protein 4.2, and band 3, ANKYRIN defects are most common
what CAN permeate the phospholipid bilayer of the cell?
gases, small uncharged polar molecules
three types of membrane transporters?
pumps, channels, ___porters
pumps do what?
use ATP energy for active transport AGAINST the gradient (example is Na/K pump)
ion channels do what
USUALLY transport ions with facilitated diffusion to achieve high rates of movement WITH gradient
___porters do what
these do secondary active transport
symporter = two molecules in same direction
antiporter = two molecules in different directions
dixgoxin works by what mechanism?
its a Na/K ATPase inhibitor; it helps the heart beat with a stronger and more regular beat
NCX does what
its a cation antiporter; secondary active transport; uses Na gradient made by ATPase to move Ca2+ outta da cell
What inhibits Na/Ca exchange
digoxin INDIRECTLY inhibits NCX because the ATPase is blocked that provides the sodium gradient
