L14 Membranes

A  hydrophilic heads

B  lipids

C  Proteins

D  Carbohydrates

A  a bilayer made of lipids with saturated 18 carbon-fatty acids

B  a bilayer made of lipids with saturated 16 carbon-fatty acids

C  a bilayer made of lipids with polyunsaturated 18 carbon-fatty acids

D  a bilayer made of lipids with polyunsaturated 16 carbon-fatty acids

E  All of the above are equivalent in fluidity.

A  water moves out of the slug, causing dehydration

B  water moves into the slug, causing it to swell

C  salt moves out of the slug, depriving it of essential minerals

D  salt moves into the slug, poisoning it

A  Diffusion

B  Semi-permeable

C  Osmosis

D  Concentration gradient

A  Isotonic

B  Homeostasis

C  Hypertonic

D  Hypotonic

A  Diffusion

B  Isotonic

C  Solution

D  Osmosis

A  swell

B  stay the same size

C  impossible to tell

D  shrink

A  active transport.

B  pinocytosis.

C  osmotic pressure.

D  osmosis.

A  continue to move across the membrane in both directions.

B  stop moving across the membrane.

C  move across the membrane to the outside of the cell.

D  move across the membrane to the inside of the cell.

A  Simple diffusion

B  Facilitated diffusion

C  Symport

D  Pump

A  primary active transport

B  secondary active transport

C  specific gas transport proteins

D  passive diffusion through the lipid bilayer

A  double bonds between carbon atoms in the fatty acid tails

B  steroid lipids at certain temperatures

C  cholesterol at certain temperatures

D  poor alignment of the fatty acids tails

E  all of the above

A  Small inorganic ions can diffuse through a cell membrane along a concentration gradient.

B  Small polar molecules cannot be transported through a cell membrane against a concentration gradient.

C  Small polar molecules can diffuse through a cell membrane along a concentration gradient.

D  Small polar molecules require specific transport systems for passage across a membrane.

A  Cell membranes retain the contents of cells.

B  Cell membranes are impermeable to most molecules.

C  Cell membranes maintain the shape of cells.

D  Cell membranes are permeable to most inorganic ions.

A  Transmembrane porins have hydrophilic amino acids that point inwards in the beta-barrels.

B  Integral membrane proteins have transmembrane domains rich in hydrophobic amino acids.

C  Integral membrane proteins are anchored to the lipid bilayer by ionic bonds.

D  Integral membrane proteins have ends rich in hydrophilic amino acids.

A  Membrane fluidity is increased when there is a high proportion of cis unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer.

B  Membrane fluidity is increased when there is a high proportion of saturated fatty acids in the glycerophosphate molecules that make up the bilayer.

C  Membrane fluidity is increased when there is a high proportion of trans unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer.

D  Membrane fluidity is decreased when there is a high proportion of cis unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer.

A  Lateral movement of membrane lipids is catalysed by special proteins.

B  The inner and outer halves of the lipid bilayer are identical.

C  Transverse movement of membrane lipids within the bilayer is unrestricted.

D  Lateral movement of membrane lipids occurs rapidly within the plane of the bilayer.

A  proteins

B  cholesterol

C  magnesium ions

D  ATP

E  None of the answers is correct.

A  membrane fluidity

B  membrane fluidity and membrane melting temperatures.

C  membrane asymmetry

D  All of the answers are correct.

E  membrane melting temperatures.

A  Active transport

B  Passage through ion channels

C  facilitated diffusion

D  Diffusion through a uniport

A  free fatty acids.

B  lipids that contain sphingosine.

C  unsaturated fatty acids.

D  glycolipids

A  positioned equally on both sides of the membrane.

B  positioned on the inside center of the bilayer.

C  positioned on the intracellular side of the membrane.

D  positioned on the extracellular side of the membrane.

E  also covalently attached to membrane proteins

A  a bilayer made of lipids with polyunsaturated 16 carbon-fatty acids

B  a bilayer made of lipids with polyunsaturated 18 carbon-fatty acids

C  a bilayer made of lipids with saturated 16 carbon-fatty acids

D  a bilayer made of lipids with saturated 18 carbon-fatty acids

E  All of the above are equivalent in fluidity.

A  two

B  one

C  None of the answers is correct.

D  infinite

E  varying thickness, depending on structure

A  None of the answers is correct.

B  All of the answers are correct

C  carbohydrates

D  lipids and proteins

A  cholesterol

B  integral membrane proteins in contact with the cytoplasm

C  glycolipids

D  lipid-linked proteins

A  translocation

B  asymmetric longitudinal flipping

C  kinesin-mediated movement

D  flip-flopping

E  lateral diffusion

A  selective permeability

B  None of the answers is correct.

C  amphipathic nature

D  bilayer

E  asymmetry

A  The transport of a molecule up its gradient is an exergonic process

B  Movement of one molecule down its gradient is an entropically driven process

C  Passage through a channel allows polar and charged compounds to avoid the hydrophobic core of the plasma membrane, which would otherwise block their entry into the cell.

D  The transport of a molecule up its gradient is an energy-requiring process.

A  Concentrated solutes

B  Energy

C  Carrier proteins

D  Water

A  An area of equilibrium to an area of high concentration

B  An area of low concentration to an area of high concentration

C  An area of high concentration to an area of low concentration

D  All of the above

A  oxidizer

B  diffuser

C  reducer

D  pump

E  transporter

A  diffusion

B  osmosis

C  facilitated diffusion

D  None of the choices are correct

E  active transport

A  There are electrostatic and hydrogen-bonding attractions between the polar head groups and water molecules.

B  An entropy increase powers diffusion across the membrane.

C  In accord with the Second Law of Thermodynamics, molecules spontaneously move from a region of higher concentration to one of lower concentration

D  The outside surface of a beta barrel is hydrophylic

A  passive transport

B  secondary active transport

C  simple diffusion

D  facilitated diffusion

E  primary active transport

A  driven by a difference of solute concentration

B  not specific with respect to the substrate

C  endergonic

D  driven by ATP

E  generally irreversible

A  synthesizing thicker membranes to insulate the cell.

B  increasing its metabolic rate to generate more heat.

C  shifting from aerobic to anaerobic metabolism.

D  putting more unsaturated fatty acids into its membranes.

E  putting longer-chain fatty acids into its membranes.

A  an increase in fatty acyl chain length.

B  the binding of water to the fatty acyl side chains.

C  a decrease in temperature.

D  an increase in the number of double bonds in fatty acids.

A  Individual lipid molecules are free to diffuse laterally in the surface of the bilayer.

B  Polar, but uncharged, compounds readily diffuse across the bilayer.

C  The bilayer is stabilized by covalent bonds between neighboring phospholipid molecules.

D  The polar head groups face inward toward the inside of the bilayer.

E  Individual lipid molecules in one face (monolayer) of the bilayer readily diffuse (flip-flop) to the other monolayer.

A  The domains that protrude on the cytoplasmic face of the plasma membrane nearly always have covalently attached oligosaccharides.

B  They can be removed from the membrane with high salt or mild denaturing agents.

C  They undergo constant rotational motion that moves a given domain from the outer face of a membrane to the inner face and then back to the outer.

D  The secondary structure in the transmembrane region consists solely of alpha-helices or beta-sheets.

A  hot water

B  a solution containing detergent

C  a solution of high ionic strength

D  a chelating agent that removes divalent cations

E  a buffer

A  penetrate deeply into the lipid bilayer

B  can be released from membranes only by treatment with detergents

C  may have functional units on both sides of the membrane

D  are generally noncovalently bound to membrane lipids