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 polyunsaturated 18 carbon-fatty acids

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

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

E  All of the above are equivalent in fluidity.

A  salt moves into the slug, poisoning it

B  water moves out of the slug, causing dehydration

C  water moves into the slug, causing it to swell

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

A  Diffusion

B  Osmosis

C  Concentration gradient

D  Semi-permeable

A  Homeostasis

B  Hypertonic

C  Isotonic

D  Hypotonic

A  Solution

B  Diffusion

C  Isotonic

D  Osmosis

A  swell

B  impossible to tell

C  stay the same size

D  shrink

A  osmosis.

B  pinocytosis.

C  osmotic pressure.

D  active transport.

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

B  continue to move across the membrane in both directions.

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

D  stop moving across the membrane.

A  Facilitated diffusion

B  Symport

C  Simple diffusion

D  Pump

A  secondary active transport

B  specific gas transport proteins

C  passive diffusion through the lipid bilayer

D  primary active transport

A  poor alignment of the fatty acids tails

B  cholesterol at certain temperatures

C  double bonds between carbon atoms in the fatty acid tails

D  steroid lipids at certain temperatures

E  all of the above

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

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

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

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

A  Cell membranes maintain the shape of cells.

B  Cell membranes are impermeable to most molecules.

C  Cell membranes are permeable to most inorganic ions.

D  Cell membranes retain the contents of cells.

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

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

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

D  Integral membrane proteins have transmembrane domains rich in hydrophobic 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 trans unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer.

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

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

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

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

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

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

A  proteins

B  cholesterol

C  ATP

D  magnesium ions

E  None of the answers is correct.

A  membrane fluidity and membrane melting temperatures.

B  membrane fluidity

C  membrane melting temperatures.

D  membrane asymmetry

E  All of the answers are correct.

A  facilitated diffusion

B  Diffusion through a uniport

C  Passage through ion channels

D  Active transport

A  lipids that contain sphingosine.

B  unsaturated fatty acids.

C  glycolipids

D  free fatty acids.

A  positioned on the extracellular side of the membrane.

B  positioned on the inside center of the bilayer.

C  positioned on the intracellular side of the membrane.

D  positioned equally on both sides 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 18 carbon-fatty acids

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

E  All of the above are equivalent in fluidity.

A  two

B  infinite

C  None of the answers is correct.

D  one

E  varying thickness, depending on structure

A  All of the answers are correct

B  lipids and proteins

C  carbohydrates

D  None of the answers is correct.

A  glycolipids

B  integral membrane proteins in contact with the cytoplasm

C  lipid-linked proteins

D  cholesterol

A  translocation

B  flip-flopping

C  kinesin-mediated movement

D  asymmetric longitudinal flipping

E  lateral diffusion

A  bilayer

B  selective permeability

C  asymmetry

D  amphipathic nature

E  None of the answers is correct.

A  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.

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

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

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

A  Energy

B  Water

C  Carrier proteins

D  Concentrated solutes

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

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

C  An area of equilibrium to an area of high concentration

D  All of the above

A  diffuser

B  reducer

C  pump

D  oxidizer

E  transporter

A  osmosis

B  facilitated diffusion

C  active transport

D  None of the choices are correct

E  diffusion

A  The outside surface of a beta barrel is hydrophylic

B  An entropy increase powers diffusion across the membrane.

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

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

A  secondary active transport

B  primary active transport

C  facilitated diffusion

D  passive transport

E  simple diffusion

A  driven by ATP

B  driven by a difference of solute concentration

C  not specific with respect to the substrate

D  endergonic

E  generally irreversible

A  putting more unsaturated fatty acids into its membranes.

B  increasing its metabolic rate to generate more heat.

C  putting longer-chain fatty acids into its membranes.

D  synthesizing thicker membranes to insulate the cell.

E  shifting from aerobic to anaerobic metabolism.

A  a decrease in temperature.

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

C  an increase in fatty acyl chain length.

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

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

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

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

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

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

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

A  hot water

B  a chelating agent that removes divalent cations

C  a solution containing detergent

D  a buffer

E  a solution of high ionic strength

A  penetrate deeply into the lipid bilayer

B  may have functional units on both sides of the membrane

C  are generally noncovalently bound to membrane lipids

D  can be released from membranes only by treatment with detergents