Upgrade to remove ads
16: Membrane Proteins
Terms in this set (44)
The melting temperature (Tm) of a membrane is slightly below
Below Tm, non-covalent interactions lock lipids into a _________ ______where motion of individual lipids is limited. (LO)
Above Tm, lipids are ______ with rapid motion in the plane of the membrane and more motion within the lipid interior (Ld)
At mammalian physiologic temperatures (20-40C), biological membranes are fluid and maintained in a transition state between
LO and LD
Fluidity is determined by
Saturated/unsaturated fatty acid composition
Pi bonds lower
What three things effect fluidity
(2) Fatty Acid Composition
(3) Sterol Content
In ______________, the same membrane fluidity is maintained when temperatures change.
Lateral diffusion in the plane of the bilayer occurs very...
____________ _____________ requires a charged head group to leave the aqueous environment and move into the hydrophobic interior of the bilayer.
Transbilayer movement requires a large
Positive free-energy change input
Uncatalyzed lateral diffusion is
Uncatalyzed transbilayer (flip-flop diffusion) is
Phospholipids destined for the outer surface of the membrane (that are synthesized on cytosolic ER membranes) require a
Mechanism for transfer
Asymmetric distribution of lipids predicts the existence of enzymes that catalyze
Moves PE and PS from outer to cytosolic leaflet
requires ATP Hydrolysis
Example: P-type ATPase
Moves phospholipids from cytosolic to outer leaflet
requires ATP Hydrolysis
Example: ABC transporter
Moves lipids in either direction, toward equilibrium
does NOT require ATP
Membrane microdomains enriched with cholesteroland sphingolipids in outer leaflet
These are thick and have a more liquid-ordered state
Lipid rafts are rich in what kind of proteins?
____________- is present in both leaflets. It fills the space under the head groups of sphingolipids or crowds the fatty acyl chains in the apposing leaflet
Adding ________ to a membrane maintains membrane fluidity over a broader range of lipid composition by
and breaking up
van der Waal interactions
Cholesterol can interact with unsaturated fatty acids to lower
Cholesterol will interact with phospholipids (containing sat fat acyl chains) to fluidize the bilayer driving them to a more
What are the three (3) features of membrane fusion?
(1) Fusion occurs without losing membrane continuity
(2) Fusion requires changes in membrane curvature
(3) Specific proteins may induce curvature
An example of membrane fusion
Neurotransmitter release at a synapse
Neurotransmitters are packaged in ________ which fuse with the membrane
v-SNARE and t-SNARE are integral proteins that bind to each other and...
Zip up into a bundle of helices
Botox is a protease that attacks what two (2) complexes...
Primary active transport
Active transport that relies directly on the hydrolysis of ATP.
Movement of a solute from an area of high concentration to an area of low concentration
nonpolar compounds only, down conc. gradient
Secondary active transport
Active transport that relies indirectly on the energy obtained from ionic gradients
Movement of specific molecules across cell membranes through protein channels
down conc. gradient
Transport protein through which ions can pass
Transporters are essentially...
Proteins form noncovalent interactions with dehydrated solute to replace
H-bonding with water
An electrically neutral solute moves toward the side of __________ concentration
The rate of movement of an electrical solute is
An electrically charged solute is controlled by a combination of the electrical gradient or membrane potential (Vm) and the ration of chemical conc. (C2/C1).
Ions will move across the membrane until eletrochemical potential reaches what?
Proteins act as a barrier between
Solute and hydrophobic lipids
Membrane proteins that speed the movement of a solute across a membrane by facilitating diffusion are called
Transporters and Channels
- 1 Gate
- NOT a Pump
- NOT saturable
- Allows transmembrane transport approaching the limit of free diffusion
- 2 Gates
- Binds substrates with HIGH specificity
- Transports at rates BELOW the limits of free diffusion
YOU MIGHT ALSO LIKE...
Chapter 11 Test Bank
Biochem Exam 3 Chapter 11
OTHER SETS BY THIS CREATOR
Top 200 Practice
Diabetes Drugs (Brand:Generic)
Diabetes Drugs (Drug:Class)
OTHER QUIZLET SETS
Psych 110 M3 Abnormal Psych
Ch. 10 Social Stratification
1.00 Final Exam Prep
Transport Across the membrane