Lipids: Chapter 11 Flashcards
How many molecules of membrane lipid are there for each molecule of protein in E. Coli?
200
What’s true about sterols in membranes?
Sterol lipids are common in human cell plasma membranes
Whats false about the composition of biological membranes?
In a given eukaryotic cell type, all intracellular membranes have essentially the same complement of lipids and proteins
Which statement about the composition of mitochondrial membranes is true?
Inner and outer membranes of mitochondria have different protein compositions
Characteristics of membrane proteins:
Covalently attached to lipid/carb moities; composed of the same 20 aa’s as soluble proteins; diffuse laterally in the membrane unless they are anchored
Peripheral proteins are:
Noncovalently attached to membrane lipids
Integral membrane proteins can be extracted with:
Solution containing detergent
Shortest alpha helix that can span a membrane bilayer has ____ aa residues
20
A hydropathy plot is used to:
Predict whether a given protein sequence contains membrane-spanning segments
Whats true of integral membrane proteins:
Hydropathy plot reveals one or more regions with a high hydropathy index
General feature of lipid bilayer in all biological membranes:
Individual lipid molecules are free to diffuse laterally in the surface of the bilayer
Type of motion least common in biological membranes:
Flip-flop diffusion of phospholipids from one leaflet to another
Fluidity of lipid side chains in the interior of a bilayer is generally increased by:
Increase in the number of double bonds in fatty acids
Fluidity of a lipid bilayer will be increased by:
Increasing the temperature
When a bacterium switches from high growth temp to low growth temp, it compensates by:
Putting more unsaturated fatty acids into its membranes
When biological membranes are viewed with an electron microscope after freeze-fracturing, particles of various sizes stand out against a smooth background. Which statement below is correct?
The particles are individual proteins or protein complexes
Integrins are:
Membrane proteins that mediate cell adhesion
A process not involving the fusion of two membranes or two regions of the same membranes is:
Entry of glucose into cells
According to the current HIV model, what is not involved in the process of membrane fusion?
Viral chromosome
What is true about facilitated diffusion:
Specific membrane proteins lower the Ea for mvmt of the solute through the membrane
Facilitated diffusion through a biological membrane is:
Driven by a difference in solute concentration
Glucose transport into erythrocytes is an example of:
Facilitated diffusion
For the process of solute transport, the constant Kf is:
Analogous to Km for an enzyme-catalyzed rxn
Type of membrane transport that uses ion gradients as the energy source is:
Secondary active transport
The free energy change for glucose uptake into the cell is:
About 10 kJ/mol
Free-energy change for the transport of K+ across the cell membrane is:
15 kJ/mol
An electrogenic Na+ transporter
Transports Na+ w/o concurrent transport of any other charged species
Movement of water across the cell membrane is facilitated by proteins called:
Aquaporins
Specificity of the potassium channel for K+ over Na+ is mainly the result of the:
Differential interaction with the selectivity filter protein
A ligand-gated ion channel (such as nicotinic acetylcholine receptor) is:
Membrane protein that permits an ion to pass through the membrane only when opened by the appropriate ion
