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 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  water moves into the slug, causing it to swell

B  salt moves into the slug, poisoning it

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

D  water moves out of the slug, causing dehydration

A  Osmosis

B  Concentration gradient

C  Diffusion

D  Semi-permeable

A  Homeostasis

B  Hypertonic

C  Hypotonic

D  Isotonic

A  Diffusion

B  Isotonic

C  Solution

D  Osmosis

A  shrink

B  impossible to tell

C  swell

D  stay the same size

A  osmosis.

B  osmotic pressure.

C  pinocytosis.

D  active transport.

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

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

C  continue to move across the membrane in both directions.

D  stop moving across the membrane.

A  Simple diffusion

B  Facilitated diffusion

C  Pump

D  Symport

A  secondary active transport

B  specific gas transport proteins

C  primary active transport

D  passive diffusion through the lipid bilayer

A  cholesterol at certain temperatures

B  poor alignment of the fatty acids tails

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 can diffuse through a cell membrane along a concentration gradient.

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

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

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

A  Cell membranes are permeable to most inorganic ions.

B  Cell membranes retain the contents of cells.

C  Cell membranes maintain the shape of cells.

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

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

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 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  Transverse movement of membrane lipids within the bilayer is unrestricted.

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

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

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

A  None of the answers is correct.

B  ATP

C  cholesterol

D  proteins

E  magnesium ions

A  membrane asymmetry

B  membrane fluidity and membrane melting temperatures.

C  membrane fluidity

D  membrane melting temperatures.

E  All of the answers are correct.

A  Diffusion through a uniport

B  facilitated diffusion

C  Passage through ion channels

D  Active transport

A  unsaturated fatty acids.

B  lipids that contain sphingosine.

C  free fatty acids.

D  glycolipids

A  also covalently attached to membrane proteins

B  positioned on the extracellular side of the membrane.

C  positioned on the intracellular side of the membrane.

D  positioned on the inside center of the bilayer.

E  positioned equally on both sides of the membrane.

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  None of the answers is correct.

B  two

C  one

D  varying thickness, depending on structure

E  infinite

A  All of the answers are correct

B  None of the answers is correct.

C  lipids and proteins

D  carbohydrates

A  integral membrane proteins in contact with the cytoplasm

B  cholesterol

C  glycolipids

D  lipid-linked proteins

A  translocation

B  flip-flopping

C  asymmetric longitudinal flipping

D  kinesin-mediated movement

E  lateral diffusion

A  selective permeability

B  amphipathic nature

C  asymmetry

D  bilayer

E  None of the answers is correct.

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

B  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.

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

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

A  Concentrated solutes

B  Carrier proteins

C  Energy

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  reducer

C  pump

D  transporter

E  diffuser

A  osmosis

B  None of the choices are correct

C  facilitated diffusion

D  diffusion

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  The outside surface of a beta barrel is hydrophylic

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  primary active transport

C  secondary active transport

D  facilitated diffusion

E  simple diffusion

A  driven by ATP

B  generally irreversible

C  endergonic

D  not specific with respect to the substrate

E  driven by a difference of solute concentration

A  increasing its metabolic rate to generate more heat.

B  shifting from aerobic to anaerobic metabolism.

C  putting more unsaturated fatty acids into its membranes.

D  synthesizing thicker membranes to insulate the cell.

E  putting longer-chain fatty acids into its membranes.

A  a decrease in temperature.

B  an increase in fatty acyl chain length.

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

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

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

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

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

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

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

A  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.

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

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  hot water

B  a solution containing detergent

C  a chelating agent that removes divalent cations

D  a solution of high ionic strength

E  a buffer

A  may have functional units on both sides of the membrane

B  penetrate deeply into the lipid bilayer

C  can be released from membranes only by treatment with detergents

D  are generally noncovalently bound to membrane lipids