Biochemistry Exam III

In the figure of monosaccharides, which one is ribose? a) A b) B c) C d) D e) None of the above

B

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 sucose is a reducing sugar

a) Both anomeric carbons are involved in the glycosidic bond

What carbohydrate is the most abundant organic compound in the biosphere? a) Cellulose b) Starch c) Maltose d) Glucose e) Amylopectin

a) Cellulose

Cartilage-matrix proteoglycan has all of the following properties EXCEPT: a) Is a component of the cell membrane b) as reversible hydration dehydration properties c) contains both N-linked and O-linked oligosaccharides d) helps maintain the flexibility and resilience of cartilage e) contains O-linked karatan sulfate

a) Is a component of the cell membrane

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) cardiolipid

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

What property causes cellulose molecules to form long, straight chains and a proper supportive structure? a) osmolarity b) B linkages c) molecular weight d) glucose residues e) heteropolymeric structure

b) B linkages

Maltose is a disaccharide composed of: a) a-d glucopyranose and B-d fructofuranose b) a-d glucopyranose and a-d glucopyranose c) a-d galactopyranose and a-d glucopyranose d) B-d fructofuranose and a-d galactopyranose e) B-d glucopyranose and B-d fructofuranose

b) a-d glucopyranose and a-d glucopyranose

What term describes molecules that have both hydrophilic and hydrophobic moieties? a) amphoteric b) amphipathic c) amphibian d) amphiprotic e) amphiaphomitic

b) amphipathic

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

How many molecules thick are membranes? a) one b) two c) three d) varying thickness e) infinite

b) two

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 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 a 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

Two monosaccharides that differ in sterochemistry at only a single asymmetric carbon are called: a) Aldoses b) Pentoses c) Anomers d) Epimers e) Enantiomers

d) Epimers

Which monosaccharide lacks an asymmetric carbon atom? a) fructose b) mannose c) altrose d) dihydroxyacetone e) galactose

d) dihydroxyacetone

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

In the alpha anomer of cyclic hemiacetal, the ________ hydroxyl is on the ______ side of the ring as the ______ hydroxl. 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

Which 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

MOST glycogen monomers are connected by what type of linkage? a) a-1,6 b) B-1,4 c) a-1,4 and B-1,6 d) a-1,6 and B-1,4 e) a-1,4

e) a-1,4

Which of the following accurately describes lactose? a) An aldohexose b) contains a B-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 of 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