L14 Membranes

A  Carbohydrates

B  lipids

C  Proteins

D  hydrophilic heads

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 saturated 16 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  salt moves into the slug, poisoning it

B  water moves into the slug, causing it to swell

C  water moves out of the slug, causing dehydration

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

A  Semi-permeable

B  Osmosis

C  Diffusion

D  Concentration gradient

A  Hypotonic

B  Homeostasis

C  Hypertonic

D  Isotonic

A  Solution

B  Osmosis

C  Isotonic

D  Diffusion

A  swell

B  shrink

C  impossible to tell

D  stay the same size

A  active transport.

B  osmotic pressure.

C  pinocytosis.

D  osmosis.

A  continue to move across the membrane in both directions.

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

C  stop moving across the membrane.

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

A  Pump

B  Symport

C  Facilitated diffusion

D  Simple diffusion

A  secondary active transport

B  specific gas transport proteins

C  passive diffusion through the lipid bilayer

D  primary active transport

A  cholesterol at certain temperatures

B  steroid lipids at certain temperatures

C  double bonds between carbon atoms in the fatty acid tails

D  poor alignment of the fatty acids tails

E  all of the above

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

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

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

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

A  Cell membranes are impermeable to most molecules.

B  Cell membranes are permeable to most inorganic ions.

C  Cell membranes maintain the shape of cells.

D  Cell membranes retain the contents of cells.

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

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

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

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

A  Membrane fluidity is decreased 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 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 trans unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer.

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

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

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

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

A  ATP

B  magnesium ions

C  cholesterol

D  None of the answers is correct.

E  proteins

A  All of the answers are correct.

B  membrane fluidity and membrane melting temperatures.

C  membrane melting temperatures.

D  membrane asymmetry

E  membrane fluidity

A  Active transport

B  facilitated diffusion

C  Passage through ion channels

D  Diffusion through a uniport

A  unsaturated fatty acids.

B  free fatty acids.

C  lipids that contain sphingosine.

D  glycolipids

A  positioned on the intracellular side of the membrane.

B  positioned on the inside center of the bilayer.

C  positioned equally on both sides of the membrane.

D  also covalently attached to membrane proteins

E  positioned on the extracellular side of the membrane.

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

B  a bilayer made of lipids with saturated 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  one

B  varying thickness, depending on structure

C  two

D  None of the answers is correct.

E  infinite

A  None of the answers is correct.

B  carbohydrates

C  lipids and proteins

D  All of the answers are correct

A  lipid-linked proteins

B  cholesterol

C  glycolipids

D  integral membrane proteins in contact with the cytoplasm

A  flip-flopping

B  asymmetric longitudinal flipping

C  lateral diffusion

D  translocation

E  kinesin-mediated movement

A  asymmetry

B  amphipathic nature

C  bilayer

D  None of the answers is correct.

E  selective permeability

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

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

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

A  Water

B  Concentrated solutes

C  Energy

D  Carrier proteins

A  An area of equilibrium to an area of high concentration

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

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

D  All of the above

A  diffuser

B  oxidizer

C  pump

D  reducer

E  transporter

A  None of the choices are correct

B  diffusion

C  facilitated diffusion

D  osmosis

E  active transport

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

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

C  An entropy increase powers diffusion across the membrane.

D  The outside surface of a beta barrel is hydrophylic

A  facilitated diffusion

B  secondary active transport

C  primary active transport

D  passive transport

E  simple diffusion

A  not specific with respect to the substrate

B  driven by a difference of solute concentration

C  endergonic

D  driven by ATP

E  generally irreversible

A  putting more unsaturated fatty acids into its membranes.

B  shifting from aerobic to anaerobic metabolism.

C  increasing its metabolic rate to generate more heat.

D  putting longer-chain fatty acids into its membranes.

E  synthesizing thicker membranes to insulate the cell.

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

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

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

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

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  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.

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

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

A  a buffer

B  hot water

C  a chelating agent that removes divalent cations

D  a solution containing detergent

E  a solution of high ionic strength

A  may have functional units on both sides of the membrane

B  can be released from membranes only by treatment with detergents

C  are generally noncovalently bound to membrane lipids

D  penetrate deeply into the lipid bilayer