Exam 3 BICH 410 Carr TAMU
the shortes a-helix segment that will span a membrane bilayer has about ____ amino acid residues A) 5 B) 20 C) 50 D) 100 E) 200
20
Which of the following describes the liquid-ordered (Lo) state? A) composed of cholesterol, sphingolipids and GPI-anchored proteins B) bilayer thickness is at its maximum C) surface area per lipid is increased D) high lipid ordering of So state, but translational disorder of Ld state E) A&D
A&D
Which of the following statements are true regarding fatty acids? A) fatty acids with fewer than 14 carbons are the most common B) Even number of carbons, because synthesis of fatty acids occurs in 2 carbon units C) Fatty acids with conjugated double bonds are the most common type of fatty acids D) In higher plants and animals, C16 and C18 species predominate in membrane lipids E) B & D
B & D, even number of carbons, because synthesis of fatty acids occurs in 2 carbon units and in higher plants and animals, C16 and C18 species predominate in membrane lipids
The polar head group of glycosphingolipids is found attached to which group of the backbone? A) C1-phosphate B) C2-OH C) C3-OH D) C1-OH E) C2-NH
C1-OH
All of the following describe why fats are better stores of energy than carbohydrates, EXCEPT: A) Carbohydrates are more hydrated than fats B) Fats are more closely packed than carbohydrates C) Carbohydrates are more reduced than fats. D) Fats weigh less than carbohydrates E) No exceptions. All of the above are true.
Carbohydrates are more reduced than fats
Which of the following statements about stereoisomers is TRUE? A) Diastereomers are monosaccharides that have only two stereoisomers B) Anomers are a special type of epimer C) Formation of a hemiacetal, or hemiketal, creates a new chiral center D) Enantiomers differ only at the highest numbered chiral carbon E) The position of the hydroxyl group on the anomeric carbon is either "D", or "L"
Formation of a hemiacetal, or hemiketal, creates a new chiral center
Which amino acid would most likely be found at the water-lipid interface of an integral membrane protein? A) D B) E C) F D) G E) H
H; Histidine
All of the following describe the Na+/K+ Pump, EXCEPT: A) It is an example of active transport B) It is inhibited by the binding of ouabain to the cytoplasmic domain C) In one cycle of ATP hydrolysis, two K+ are pumped into the cell D) In one cycle of ATP hydrolysis, three Na+ are pumped out of the cell E) It is an antiporter
It is inhibited by the binding of ouabain to the cytoplasmic domain
Which of the following transport conditions is associated with a negative change in free energy? A) K+ transported from high concentration to low concentration B) Na+ transported from low concentration to high concentration C) C6H12O6 transport out of the cell after a meal D) all of the above E) none of the above
K+ transported from high concentration to low concentration
Oligo- and polysaccharides allow for all of the following EXCEPT: A) strength, due to a large number of inter- and intra-molecular H-bonds B) storage of large numbers of glucose molecules, without osmotic stress C) extension of protein structures to function above the cell glycocalyx D) information for cell-cell communication E) no exceptions. all of the above are true.
No exceptions. All of the above are true.
All of the following statements regarding glycoproteins are true, EXCEPT: A) Removal of monosaccharides from O-linked polysaccharides acts as a timer for protein degradation. B) Branched, N-linked oligosaccharides are added during translation and modified in the Golgi Apparatus C) Addition of oligosaccharides stabilizes protein conformation and protects from proteolysis D) O-linked oligosaccharides solubilize the polypeptide to raise the functional domain above the glycocalyx E) No exceptions. All of the statements are true
Removal of monosaccharides from O-linked polysaccharides act as a timer fro protein degradation
All of the following statements regarding glucose are true, EXCEPT: A) In the beta anomer, the OH at C-4 is down B) It is an aldohexose C) The highest numbered chiral carbon is C-6 D) The O atom in the hemiacetal ring is the hydroxyl oxygen from C-5 E) It is a monosaccharide
The highest numbered chiral carbon is C-6
Cellulose is A) a linear copolymer of glucose and galactose B) a branched polymer of glucose C) a linear polymer of glucose with a(1->4) linkages D) a linear polymer of glucose with B(1-->4) linkages E) sometimes called starch
a linear polymer of glucose with B(1->4) linkages
The most common trans-membrane domain found in integral membrane proteins is: A) beta-barrels of all non-polar amino acids in the primary structure B) a-helices of charged amino acids that form channels via extensive hydrogen bonding C) triple helix of left-handed helices D) a-helices of all nonpolar amino acids in the primary structure E) coiled-coil structures with a heptad repeat in the primary structure
a-helices of all nonpolar amino acids in the primary structure
Which of the following describes transport in the absence of an integral membrane protein? A) secondary active transport B) facilitated diffusion C) passive diffusion D) active transport E) all of the above
active transport
Phosphatidic acid has which of the following components? A) phosphate B) glycerol C) ester linkage D) acyl chain E) all of the above
all of the above
Unsaturated fatty acids: A) are commonly found in plants and animals B) usually contain a double bond with cis stereochemistry C) sometimes contain multiple double bonds D) have lower melting points than the analogous saturated fatty acids E) all of the above
all of the above
Which of the following are found as covalently attached to lipid-anchored proteins? A) thioester-linked prenyl groups? B) thioether linked fatty acid groups C) amide-linked myristic acid groups D) glycosylphosphatidylethanolamine groups E) all of the above
amide linked-myristic acid groups
Which of these polysaccharides is a branched polymer? A) chitin B) amylose C) amylopectin D) cellulose E) hyaluronic acid
amylopectin
Starch is a mixture of: A) glycogen and amylopectin B) amylose and amylopectin C) glycogen and alpha-amylose D) glycogen and cellulose E) amylose and maltose
amylose and amylopectin
A protein that transports two different solutes in different directions is called A) symporter B) uniporter C) a gap junction D) an antiporter E) a channel
an antiporter
The fluidity of the lipid acyl chains in the interior of a bilayer is generally increased by: A) a decrease in temperature B) an increase in fatty acyl chain length C) an increase in the percentage of phosphatidyl ethanolamine D) an increase in the number of double bonds in fatty acids E) the binding of water to the fatty acyl side chains
an increase in the number of double bonds in fatty acids
Saturation kinetics displays A) a linear dependence of transport rate on solute concentration B) no dependence of transport rate on solute concentration C) transport equilibrium at all solute concentrations D) an upper limit to the dependence of rate on solute concentration E) no limit to the dependence of rate on solute concentration
an upper limit to the dependence of rate on solute concentration
The transformation of a monosaccharide into its ____ is the result of interconversion with the linear form A) epimer B) diastereomer C) sugar alcohol D) anomer E) none of the above
anomer
Transport of a solute from low concentration to high concentration requires A) an input of energy in the form of ATP B) an input of energy in the form of light C) tapping energy stored in the form of an electrochemical gradient D) any one of the above E) none of the above
any one of the above
All of the following fatty acids have 18 carbons, EXCEPT: A) oleic acid B) linoleic acid C) arachidonic acid D) stearic acid E) B & D
arachidonic acid
Peripheral membrane proteins: A) can be released from membranes only by treatment with detergent(s) B) are usually denatured when released from membranes C) are generally noncovalently bound to membrane lipids D) may have functional units both sides of the membrane E) penetrate deeply into the lipid bilayer
are generally noncovalently bound to membrane lipids
Which of the following describes cartilage matrix proteoglycan? A) makes up the jelly-like inside of the eye B) contains N-linked and O-linked oligosaccharides C) contains heparin sulfate D) contains N-linked glycosaminoglycans E) is an integral membrane cell-surface proteoglycan
contains N-linked and O-linked oligosaccharides
Unsaturations ______ melting points of fatty acids and their derivatives A) maintain B) increase C) decrease D) are unrelated to E) none of the above
decrease
Which of the following is an example of a heteropolysaccharide? A)cellulose B) chitin C) hyaluronic acid D) glycogen E) starch
hyaluronic acid
Which of the following statements is a general feature of the lipid bilayer in all biological membranes? A) polar, but uncharged, compounds readily diffuse across the bilayer B) individual lipid molecules in one monolayer of the bilayer readily diffuse (flip-flop) to the other monolayer 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
individual lipid molecules are free to diffuse laterally in the surface of the bilayer
Which of the following would be most difficult to separate from the membrane? A) extrinsic proteins B) lipid-linked proteins C) hydrophilic proteins D) peripheral membrane proteins E) integral membrane proteins
integral membrane proteins
All of the following statements describe the composition of biological membranes EXCEPT: A) Triacylglycerols are not found in membranes B) the carbohydrate component of membranes is found as part of glycolipids and glycoproteins C) The plasma membrane of mammalian cells contains cholesterol D) the ratio of lipid to protein varies widely among cell types in a single organism E) intracellular membranes have the same lipids and proteins
intracellular membranes have the same lipids and proteins
Which of the following disaccharides is linked by an alpha(1->6) glycosidic bond? A) isomaltose B) lactose C) cellbiose D) sucrose E) maltose
isomaltose
All of the following describe membranes EXCEPT: A) an increased temperature increases the rate of lateral diffusion in the membrane B) Transverse diffusion does not occur at a significant timescale, without enzymes C) lateral diffusion can be restricted by intracellular components D) Lateral diffusion of the membrane protein occurs independent of bilayer composition and temperature E) lateral diffusion is restricted in microdomains enriched in cholesterol and sphingolipids
lateral diffusion of the membrane protein occurs independent of bilayer composition and temperature
Proteins that bind to specific carbohydrates are called _____ A) lectins B) pectins C) glycosaminoglycans D) proteoglycans E) chitins
lectins
Which of the following structures is favored by fatty acids and single-tailed amphiphiles? A) lipid bilayers B) micelles C) liposomes D) two-dimensional membranes E) solvent-filled vesicles
micelles
The four modes for transport across biological membranes are A) symport, uniport, antiport, and airport B) vesicle budding, vesicle targeting, vesicle docking, and vesicle fusion C) osmosis, precocious, hydrolysis, and halitosis D) van der Waals, H-bonds, ionic interactions and the hydrophobic effect E) none of the above
none of the above
All of the following describe the carbohydrates of bacterial cell walls, EXCEPT: A) made up of peptidoglycans B) exposed in gram-positive cells, between membranes in gram-negative cells C) part of lipopolysaccharide "hairs," in gram positive cells D) linear heteropolysaccharides linked by short, repeating peptides E) No exceptions. all of the above are true.
part of lipopolysaccharide "hairs," in gram-positive cells
Bacterial cell walls are composed of _____ A) peptidoglycans B) chondroitin sulfate chains C) pectin D) heparin E) proteoglycans
peptidoglycans
Release of the choline alcohol and phosphatidic acid from phosphatidyl choline results from the action of A) phospholipase A1 B) phospholipase A2 C) phospholipase B D) phospholipase C E) phospholipase D
phospholipase D
A hydropathy plot is used to: A) determine the water solubility of a globular protein B) deduce the quaternary structure of a membrane protein C) determine the water content of a native protein D) predict whether a given protein sequence contains membrane-spanning helices E) extrapolate the true molecular weight of a membrane protein
predict whether a given protein sequence contains membrane-spanning helices
Which of the following statements is consistent with the structure of biological membranes? A) all membrane proteins are integral and cross the hydrocarbon region of the membrane B) both proteins and lipids readily undergo transverse diffusion in the membrane C) membranes are symmetric D) they consist of proteins sandwiched between two layers of lipids, referred to as a lipid bilayer E) the membrane lipids self-assemble to form the bilayer
the membrane lipids self-assemble to form the lipid bilayer
With regard to passive diffusion, the greater the magnitude of the concentration gradient, A) the more likely facilitated transport is required B) the more rapid the rate of diffusion C) the easier it is to reverse the direction of solute flow D) the higher number of ATPs required for transport E) all of the above
the more rapid the rate of diffusion
Which of the following statements describes integral membrane proteins? A) they undergo constant transverse diffusion across the membrane bilayer B) the cytoplasmic domains nearly always have covalently attached oligosaccharides C) they are unusually susceptible to degradation by trypsin D) they can be removed from the membrane with high salt E) the secondary structure in the transmembrane region consists solely of a-helices or B-sheets
the secondary structure in the transmembrane region consists solely of a-helices or B-sheets
The notation (20:2) indicates which of the following about a fatty acid? A) there are 20 carbons in the chain with two trans double bonds B) There are two 20-carbon chains attached to the backbone of this fatty acid C) the 2nd carbon is connected to the 3rd by a cis-double bond D) the 20th carbon is connected to the 19th by a cis-double bond E) there are 2 cis-double bonds in this 20-carbon fatty acid
there are two cis-double bonds in this 20-carbon fatty acid
O-linked oligosaccharides are attached to an OH group on ______ A) ribose B) tyrosine C) threonine D) lysine E) glycine
threonine
Which of the following lipid types is the least polar? A) glycolipids B) glycerophospholipids C) sphingolipids D) gangliosides E) triacylglycerols
triacylglycerols
