Carr Exam 3B

Transverse diffusion in biological membranes occurs by: A) ATP-driven flip or flop of lipids by a specific integral membrane protein. B) spontaneous, rapid flip-flop of membrane proteins across the bilayer. C) fast rotation of lipids within one face (leaflet) of a membrane. D) fast diffusion of proteins and lipids within one leaflet of the membrane. E) slow diffusion of proteins and lipids within one leaflet of the membrane.

A) ATP-driven flip or flop of lipids by a specific integral membrane protein.

Why is sucrose NOT a reducing sugar? A) Both anomeric carbons are involved in the glycosidic bond. B) Only the anomeric carbon of glucose can be oxidized, and it is involved in the glycosidic bond. C) Only the anomeric carbon of fructose can be oxidized, and it is involved in the glycosidic bond. D) Neither anomeric carbon is involved in the glycosidic bond. E) None of the answers is correct because sucrose is a reducing sugar.

A) Both anomeric carbons are involved in the glycosidic bond.

Which statement about transporters is correct? A) Glucose transport into the cell is an example of facilitated diffusion. B) Ouabain blocks transport by the potassium channel. C) The potassium channel transports two potassium ions in and three sodium ions out, per ATP hydrolyzed. D) The potassium pump is an example of passive diffusion E) ATP hydrolysis is required for the function of the potassium channel.

A) Glucose transport into the cell is an example of facilitated diffusion.

What carbohydrate is the most abundant organic compound in the biosphere? A) cellulose B) starch C) maltose D) glucose E) amylopectin

A) cellulose

What membrane lipid is composed of sphingosine, fatty acid, and a single sugar residue, either glucose or galactose? A) cerebroside B) sphingomyelin C) phosphatidate D) cholesterol E) cardiolipin

A) cerebroside

Select the monosaccharide that is correctly paired with its description. A) d-fructose - ketohexose B) d-galactose - aldopentose C) d-glucose - ketohexose D) d-ribulose - ketotetrose E) d-ribose - ketopentose

A) d-fructose - ketohexose

Cartilage-matrix proteoglycan has all of the following properties EXCEPT: A) is a component of the cell membrane. B) has reversible hydration-dehydration properties. C) contains both N-linked and O-linked oligosaccharides. D) helps maintain the flexibility and resiliency of cartilage. E) contains O-linked karatan sulfate?

A) is a component of the cell membrane.

In the figure of monosaccharides, which one is ribose? A) A B) B C) C D) D E) None of the above.

B) B

Which amino acid is most likely found in a trans-membrane domain of an integral membrane protein? A) D B) G C) S D) E E) K

B) G

What term describes molecules that have both hydrophilic and hydrophobic moieties? A) amphoteric B) amphipathic C) amphibian D) amphiprotic E) amphiapomictic

B) amphipathic

The potassium channel is which type of transporter? A) passive diffusion. B) facilitated diffusion. C) active transport D) passive transport E) secondary active transport

B) facilitated diffusion.

All of the following describe trans-membrane domains of integral membrane proteins, EXCEPT: A) require detergent to release them from the membrane B) hydropathy plots predict alpha-helices and beta barrels C) all backbone amides neutralized by hydrogen bonds D) lipid-facing sidechains are nonpolar E) aqueous pore-facing side chains are polar

B) hydropathy plots predict alpha-helices and beta barrels

What proteins facilitate cell-to-cell recognition by binding to specific carbohydrate structures? A) mucoproteins B) lectins C) glycoproteins D) glycosaminoglycans E) proteoglycans

B) lectins

What complex is observed between cholesterol and certain membrane lipids? A) salt bridge B) lipid raft C) clathrate D) phospholipid domain E) precipitate

B) lipid raft

Which of the following is an 18-carbon fatty acid? A) laurate B) stearate C) palmitate D) arachiodonate E) myristate

B) stearate

All of the following describe transporters, EXCEPT: A) uniporters transport one type of solute in one direction B) they can be lipid-anchored proteins in the inner leaflet of the bilayer C) they have transport rates that saturate with excess solute D) they have aqueous pores to accommodate specific solutes E) they either facilitate diffusion, or actively transport solutes

B) they can be lipid-anchored proteins in the inner leaflet of the bilayer

All of the following describe primary active transport, EXCEPT: A) solutes are transported against their concentration gradient B) transport of an ion down its concentration gradient "pays" from transport C) light, or ATP hydrolysis "pays" for transport D) transport is coupled to an energy source E) transport is against the thermodynamic potential of the solute

B) transport of an ion down its concentration gradient "pays" from transport

How many molecules thick are membranes? A) one B) two C) three D) varying thickness E) infinite

B) two

Maltose is a disaccharide composed of: A) α-d-glucopyranose and β-d fructofuranose. B) α-d-glucopyranose and α-d-glucopyranose. C) α-d-galactopyranose and α-d-glucopyranose. D) β-d-fructofuranose and α-d-galactopyranose. E) β-d-glucopyranose and β-d-fructofuranose.

B) α-d-glucopyranose and α-d-glucopyranose.

What property causes cellulose molecules to form long, straight chains and a proper supportive structure? A) osmolarity B) β linkages C) molecular weight D) glucose residues E) heteropolymeric structure

B) β linkages

Why is it more advantageous to store glucose in the form of glycogen rather than in its free form? A) Glycogen is more water soluble than glucose. B) Glycogen strengthens the cell wall. C) Glucose is osmotically stressful to the cell. D) Glycogen is more reactive than glucose. E) Glucose is less calorie-dense than glycogen.

C) Glucose is osmotically stressful to the cell.

Which of the following statements is true? A) Hydrophilic interactions are the major driving force for the formation of lipid bilayers. B) The favored structure for most glycerophospholipids and sphingolipids in aqueous media is a micelle. C) Lipid bilayer membranes have a very low permeability for ions and polar molecules. D) There are electrostatic and hydrogen-bonding attractions between the hydrocarbon tails and water molecules. E) Micelles have aqueous compartments and are composed of glycolipids.

C) Lipid bilayer membranes have a very low permeability for ions and polar molecules.

All of the following statements about peripheral membrane proteins are true, EXCEPT: A) They are membrane proteins that interact with the polar head groups of the membrane lipids. B) They are membrane proteins that can bind to integral membrane proteins. C) They are membrane proteins that span the lipid bilayer. D) Interactions with the membrane lipids can be disrupted by adding a high concentration of salt. E) They are membrane proteins that can interact with one layer of the membrane lipid bilayer.

C) They are membrane proteins that span the lipid bilayer.

Which of the following lipids sweeps out a cone shape when it rotates on its vertical axis? A) sphingomyselin B) posphatidylinositol C) ganglioside D) cholesterol E) phosphatidylserine

C) ganglioside

A lipid anchored protein can have a ____ group attached to a(n) ______, through a ______ linkage. A) phenyl; Cys; thioester B) B) palmitoyl; N-terminus; amide C) geranylgeranyl; Cys; thioether D) myristoyl; Cys; amide E) GPI; Cys; thioester

C) geranylgeranyl; Cys; thioether

Which term describes a class of compounds with the molecular formula (CH2O)n? A) proteoglycans B) glycogen C) monosaccharides D) polysaccharides E) mucoproteins

C) monosaccharides

What is the chemical basis for the cyclization of sugars in solution? A) H-bond interaction of hydroxyl groups with each other B) formation of peptide bonds between atoms in modified sugars C) reaction of the carbonyl group with an alcohol group D) formation of hydrogen bonds between sugar and water molecules E) reaction between the aldehyde groups of sugar molecules

C) reaction of the carbonyl group with an alcohol group

Which structure is composed of an aqueous compartment (lumen) enclosed by a lipid bilayer and can be used to deliver chemicals to cells? A) micelle B) lysosome C) vesicle D) chloroplast E) ribosome

C) vesicle

Which of the following describes the Na+/K+ Pump? A) It is an example of secondary active transport. B) In one cycle of ATP hydrolysis, three K+ are pumped out of the cell. C) In one cycle of ATP hydrolysis, two Na+ are pumped into the cell. D) It is inhibited by the binding of ouabain to the extracellular domain. E) It is a symporter.

D) It is inhibited by the binding of ouabain to the extracellular domain.

Which of the following accurately describes biological membranes? A) peripheral membrane proteins act as scramblases B) lipid rafts are composed of GPI-anchored proteins attached to the cytoplasmic leaflet C) triacylglycerols are a component of rafts D) asymmetric distribution of proteins and lipids E) high salt wash removes integral membrane proteins

D) asymmetric distribution of proteins and lipids

What monosaccharide lacks an asymmetric carbon atom? A) fructose B) mannose C) altrose D) dihydroxyacetone E) galactose

D) dihydroxyacetone

Two monosaccharides that differ in stereochemistry at only a single asymmetric carbon are called: A) aldoses. B) pentoses. C) anomie's. D) epimers. E) enantiomers.

D) epimers

In passive diffusion, _____ solutes pass through the membrane from ___ to ____ concentration. A) polar, high, low B) polar, low, high C) hydrophobic, low, high D) hydrophobic, high, low E) charged, low, high

D) hydrophobic, high, low

Peripheral membrane proteins are in the _______ after lysis and in the ___ after a _____ wash. A) pellet; supernatant fraction , detergent B) pellet; pellet; high-salt C) supernatant fraction; supernatant fraction; detergent D) pellet; supernatant fraction; high-salt E) supernatant fraction; pellet; high-salt

D) pellet; supernatant fraction; high-salt

All of the following are ways to bend a membrane, EXCEPT: A) lipid shape B) interval membrane protein shape C) insertion into one leaflet by an amphipathic helix D) raft formation E) peripheral membrane protein scaffolding

D) raft formation

Sugars are commonly linked to which amino acid residues in glycoproteins? A) tyrosine and asparagine B) serine and glutamine C) serine, tyrosine, and asparagine D) serine, threonine, and asparagine E) threonine and glutamine

D) serine, threonine, and asparagine

Which of the following statements explains saturation kinetics? A) transport rate independent of [solute] B) sigmoidal dependence of transport rate on [solute] C) linear dependence of transport rate on [solute] D) transport rate dependent on [solute], with a constant rate at very high [solute] E) no transport at very high [solute]

D) transport rate dependent on [solute], with a constant rate at very high [solute]

In which kind of transport(s) do solutes transport down their concentration gradient? A) passive diffusion B) primary C) facilitated diffusion D) secondary active transport E) A & C

E) A & C

How does energy affect the functioning of the Na+-K+ ATPase? A) ATP provides energy for this pump to function. B) The pump maintains the proper cellular concentration of Na+ and K+. C) Without ATP, the pump would not be Abe to function. D) Without ATP, the pump transport only K+ E) A, B, & C

E) A, B, & C

All of the following describe motions in a membrane, EXCEPT: A) Rotation of lipids and proteins is fast. B) Decreased bilayer thickness in the L-d phase. C) Integral membrane proteins anchored to the cytoskeleton slow lateral diffusion. D) Slower movement of lipids an proteins in the L-o phase E) ATP-driven floppases move lipids from the outer to the inner leaflet

E) ATP-driven floppases move lipids from the outer to the inner leaflet

Which statement best describes why 20 amino acids are optimal to span a membrane as an alpha helix? A) The rise per amino acid is 1.5 Å. B) The hydrophobic core of a bilayer is 30 Å thick. C) The pitch of an alpha helix is 5.4 Å. D) There are 3.6 amino acids per turn. E) Both A & B

E) Both A & B

Vesicle trafficking of cargo from one compartment of the cell to another depends on A) transporters B) hemagglutinin C) SNAREs D) scaffold proteins E) C & D

E) C & D

In the α anomer of a cyclic hemiacetal, the ____ hydroxyl is on the ____ side of the ring as the ___ hydroxyl. A) C-1, opposite, C-3 B) C-2, opposite, C-6 C) C-2, same, C-6 D) C-1, same, C-6 E) C-1, opposite, C-6

E) C-1, opposite, C-6

What statement is consistent with the structure of biological membranes? A) All membrane proteins are integral and associate with the hydrophobic region of the membrane. B) Both proteins and lipids readily undergo transverse ("flip-flop") diffusion. C) Membranes are symmetric. D) A biological membrane consists of proteins sandwiched between two layers of lipids. E) The membrane lipids self-assemble to form the lipid bilayer.

E) The membrane lipids self-assemble to form the lipid bilayer.

Which of the following accurately describes lactose? A) an aldohexose B) contains a β-1,4 linkage C) digested by bacteria found in the rumen D) a reducing sugar E) both B & D

E) both B & D

Glycoproteins are normally: A) only found on membranes B) only secreted as extracellular proteins. C) only found inside organelles. D) only found in the cytoplasm. E) found on cell surfaces and secreted as extracellular proteins.

E) found on cell surfaces and secreted as extracellular proteins.

What property is used to determine the probability that a segment of a protein will be found embedded in a membrane? A) solvation B) polarity C) acidity D) entropy E) hydropathy

E) hydropathy

Carbohydrate residues attached to the membrane lipids are almost always: A) positioned on the intracellular side fo the membrane. B) positioned on the inside center of the bilayer. C) also covalently attached to membrane proteins. D) positioned equally on both sides of the membrane. E) positioned on the extracellular side of the membrane.

E) positioned on the extracellular side of the membrane.

Which of the following transporters is an example of antiporter? A) pinocytosis of dissolved nutrients. B) the potassium channel C) clathrin mediated endocytosis D) exocytosis of secretory proteins E) the sodium-potassium ATPase

E) the sodium-potassium ATPase

MOST glycogen monomers are connected by what type of linkage? A) α-1,6 B) β-1,4 C) α-1,4 and β-1,6 D) α-1,6 and β-1,4 E) α-1, 4

E) α-1, 4