L14 Membranes

A  Carbohydrates

B  Proteins

C  hydrophilic heads

D  lipids

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

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

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

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

E  All of the above are equivalent in fluidity.

A  water moves out of the slug, causing dehydration

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

C  water moves into the slug, causing it to swell

D  salt moves into the slug, poisoning it

A  Diffusion

B  Concentration gradient

C  Semi-permeable

D  Osmosis

A  Hypotonic

B  Homeostasis

C  Isotonic

D  Hypertonic

A  Isotonic

B  Solution

C  Diffusion

D  Osmosis

A  shrink

B  swell

C  impossible to tell

D  stay the same size

A  active transport.

B  osmosis.

C  pinocytosis.

D  osmotic pressure.

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

B  stop moving across the membrane.

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

D  continue to move across the membrane in both directions.

A  Facilitated diffusion

B  Simple diffusion

C  Symport

D  Pump

A  passive diffusion through the lipid bilayer

B  primary active transport

C  specific gas transport proteins

D  secondary active transport

A  poor alignment of the fatty acids tails

B  double bonds between carbon atoms in the fatty acid tails

C  cholesterol at certain temperatures

D  steroid lipids at certain temperatures

E  all of the above

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

A  Cell membranes retain the contents of cells.

B  Cell membranes maintain the shape of cells.

C  Cell membranes are permeable to most inorganic ions.

D  Cell membranes are impermeable to most molecules.

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

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

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

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

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

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

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

D  Membrane fluidity is increased 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 occurs rapidly within the plane of the bilayer.

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

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

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

A  None of the answers is correct.

B  ATP

C  cholesterol

D  proteins

E  magnesium ions

A  membrane asymmetry

B  membrane melting temperatures.

C  membrane fluidity and membrane melting temperatures.

D  membrane fluidity

E  All of the answers are correct.

A  facilitated diffusion

B  Passage through ion channels

C  Diffusion through a uniport

D  Active transport

A  glycolipids

B  lipids that contain sphingosine.

C  free fatty acids.

D  unsaturated fatty acids.

A  positioned equally on both sides of the membrane.

B  also covalently attached to membrane proteins

C  positioned on the extracellular side of the membrane.

D  positioned on the inside center of the bilayer.

E  positioned on the intracellular side of the membrane.

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

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

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

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

E  All of the above are equivalent in fluidity.

A  infinite

B  two

C  varying thickness, depending on structure

D  one

E  None of the answers is correct.

A  carbohydrates

B  All of the answers are correct

C  lipids and proteins

D  None of the answers is correct.

A  integral membrane proteins in contact with the cytoplasm

B  glycolipids

C  lipid-linked proteins

D  cholesterol

A  asymmetric longitudinal flipping

B  kinesin-mediated movement

C  translocation

D  lateral diffusion

E  flip-flopping

A  selective permeability

B  bilayer

C  amphipathic nature

D  None of the answers is correct.

E  asymmetry

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 energy-requiring process.

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

A  Water

B  Energy

C  Carrier proteins

D  Concentrated solutes

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

B  An area of equilibrium to an area of high concentration

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

D  All of the above

A  transporter

B  oxidizer

C  pump

D  reducer

E  diffuser

A  None of the choices are correct

B  facilitated diffusion

C  diffusion

D  osmosis

E  active transport

A  An entropy increase powers diffusion across the membrane.

B  The outside surface of a beta barrel is hydrophylic

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  passive transport

B  facilitated diffusion

C  primary active transport

D  secondary active transport

E  simple diffusion

A  endergonic

B  not specific with respect to the substrate

C  driven by a difference of solute concentration

D  generally irreversible

E  driven by ATP

A  increasing its metabolic rate to generate more heat.

B  putting more unsaturated fatty acids into its membranes.

C  synthesizing thicker membranes to insulate the cell.

D  shifting from aerobic to anaerobic metabolism.

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

D  a decrease in temperature.

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

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

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

D  Polar, but uncharged, compounds readily diffuse across 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  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  They can be removed from the membrane with high salt or mild denaturing agents.

A  a solution of high ionic strength

B  a solution containing detergent

C  a buffer

D  a chelating agent that removes divalent cations

E  hot water

A  penetrate deeply into the lipid bilayer

B  can be released from membranes only by treatment with detergents

C  are generally noncovalently bound to membrane lipids

D  may have functional units on both sides of the membrane