1. The amino acid alanine, shown below, contains all of the following fun<wbr>ctional groups except

1. The amino acid alanine, shown below, contains all of the following functional groups except

A. An amino group

B. A methyl group

C. An ester group.

D. A carboxyl group.

2. The three-dimensional structure (native conformation) of proteins is determined primarily by

A. Noncovalent interactions.

B. The other proteins with which it forms a complex.

C. Its amino acid sequence.

D. Molecular chaparones.

4. Paralogs and orthologs differ in that

A. Paralogs have the same amino acid sequence and orthologs have different amino acid sequences.

B. Paralogs exist in the same species and orthologs exist in different species.

C. Paralogs have the same function and orthologs have different functions.

D. Paralogs have the same three-dimensional structure and orthologs have different three-dimensional structures.

7. Osmosis is water movement across a semipermeable membrane. Which of the following is true about water movement across cell membranes

A. In a hypotonic solution, cells will swell.

B. In an isotonic solution, cells will shrink.

C. In a hypertonic solution, cells will stay the same.

D. Cells can neither shrink nor swell because water cannot penetrate the plasma membrane.

8. Cells need to be buffered because

A. They need to be able to increase or decrease their cytosolic pH to adapt to various environmental conditions.

B. Their proteins work best at low pH.

C. They need to maintain a specific cytosolic pH to keep biomolecules from being ionized.

D. They need to maintain a specific cytosolic pH to keep biomolecules at their optimal ionic state.

9. Which of the following is true about condensation reactions?

A. Condensation reactions are invariably exergonic.

B. Condensation reactions involve the depolymerizion of macromolecules.

C. Condensation reactions involve the loss of the elements of water.

D. A typical condensation reaction is the formation of ADP from ATP and inorganic phosphate.

10. Hydrophobic interactions account for

A. Why biomolecules are amphipathic.

B. Why the nonpolar regions of molecules cluster together in water.

C. The tendency of lipids to disperse in water.

D. Why the polar regions of molecules are associated with water.

11. Which of the following pairs of groups cannot form a hydrogen bond with each other (the proposed hydrogen bond is indicated by the blue rectangle)?

1. At the center of all 20 standard amino acids is what is termed the α-carbon that is covalently bonded with four other chemical groups. Which of these four chemical groups is not a normal component of all amino acids?

A. An amino group

B. A carboxyl group

C. A side chain (R group)

D. A methyl group

2. Cysteine residues play an important role in the structure of many proteins by

A. Providing covalent links between parts of a protein molecule or between two different protein chains.

B. Forming disulfide bonds with another amino acid.

C. Linking two protein chains through hydrophobic interactions.

D. Reducing two cysteine residues.

4. Which of the following amino acids has a net negative charge at pH 7.0?

A. glycine

B. threonine

C. aspartate

D. arginine

8. Two proteins that have the same molecular weight but differ in their pI are best separated by

A. Affinity chromatography.

B. Size exclusion chromatography.

C. two-dimensional electrophoresis

D. SDS polyacrylamide gel electrophoresis.

9. Which of the following is true about the Edman degradation system of sequencing polypeptides?

A. The Edman degradation system will work on any size polypeptide.

B. In the Edman degradation system the amino-terminal residue is labeled and the polypeptide is hydrolyzed to its constituent amino acids.

C. In the Edman degradation system the amino-terminal residue is labeled, cleaved and identified in each successive cycle.

D. The Edman degradation system is carried out on a machine called an edmanator.

10. The titration curve of the amino acid glycine reveals a pK1 of 2.34, a pI of 5.97, and a pK2 of 9.60. When dissolved in water, which ionic species is most likely to predominate at pH = 5.97?

1. Which of the following experiments provided the first evidence that the amino acid sequence of a polypeptide chain contains all the information required to fold the chain into its native, three-dimensional structure?

A. When ribonuclease is treated with urea, it loses its catalytic activity.

B. When denatured ribonuclease is allowed to renature, it regains its catalytic activity.

C. When renatured ribonuclease is allowed to denature, it regains its catalytic activity.

D. Addition of mercaptoethanol causes ribonuclease to regain catalytic activity.

3. Hydrogen bonds between amino acids in a polypeptide occur between which chemical groups?

A. the C=O and C-H groups

B. the C=O and C-R groups

C. the C=O groups

D. the C=O and N-H groups

5. Fibrous proteins differ from globular proteins in that

A. Fibrous proteins tend to serve structural functions, and globular proteins are more likely to be enzymes.

B. Fibrous proteins can often contain several types of secondary structure, whereas globular proteins usually consist largely of a single type of secondary structure.

C. Globular proteins are insoluble in water, and fibrous proteins are usually soluble.

D. Globular proteins are more likely than fibrous proteins to have an elaborate quaternary structure.

6. Why is the α-helix conformation in polypeptides such a stable form?

A. The α-helix structure is stabilized by hydrophobic interactions.

B. The α-helix structure is stabilized by hydrogen bonds.

C. The α-helix structure is stabilized by disulfide bonds.

D. The α-helix structure is stabilized by proline residues.

7. A protein in solution is more likely to maintain its native conformation when

A. The number of hydrogen bonds within a protein is minimized.

B. The shell of water becomes more ordered.

C. The protein is least stable.

D. Its hydrophobic residues are largely buried in the protein interior.

8. Which of the following is true about protein domains?

A. Protein domains lose their three-dimensional structure when separated from the remainder of the polypeptide chain.

B. Protein domains lose their function when separated from the remainder of the polypeptide chain.

C. Protein domains often fold into stable globular units.

D. A protein must have more than one domain to be functional.

9. Which bonds are planar (cannot rotate) in a polypeptide backbone?

A. Cα-C bonds

B. C-N bonds

C. N-Cαbonds

D. Cα-Cα bonds

10. Tertiary structures such as the twisted β sheet and the β barrel form because of

A. The natural tendency of parallel β strands to twist in a right-handed direction

B. The natural tendency of parallel β strands to twist in a left-handed direction

C. Hydrogen bonds between β strands and an α helix

D. Hydrophobic collapse

1. Based on the structures of D–glucose and D–galactose (shown below), which of the following statements is true?

2. Which of the following statements is true about the cyclic (ring) form of D– glucose?

A. The cyclic form of D–glucose is a furanose.

B. The cyclic form of D–glucose involves the formation of a covalent bond between

C. The cyclic form of D–glucose is the result of a bond forming between the C–1 and C–6 carbon atoms.

D. In aqueous solution, the cyclic form of D–glucose is rare.

3. Which of the following is true about how a disaccharide is formed from two monosaccharides?

A. Monosaccharides are linked in a reaction that eliminates water.

B. Disaccharides form when a hydoxyl group of one monosaccharide reacts with the hydroxyl group of another monosaccharide.

C. A disaccharide consists of two monosaccharides linked to each other by an Nglycosidic bond

D. Disaccharides are formed by a hydrolysis reaction.

4. The reducing end of a disaccharide or a polysaccharide is

A. The end with an anomeric carbon that cannot be oxidized.

B. The end that does not have an anomeric carbon.

C. The end of a chain with a free anomeric carbon (i.e., not involved in a glycosidic bond).

D. The end whose sugar cannot take the linear form.

7. Why is glucose not stored in its monomeric form in cells?

A. Because monomeric glucose would raise the osmolarity of the cytosol to unsafe levels

B. Because the monomeric form of glucose is not very soluble.

C. Because the monomeric form of glucose cannot be readily utilized as an energy source

D. Because glucose monomers spontaneously form polymers in the cell.

8. Which of the following is true about how sugar polymers are broken down?

A. Most animals cannot use starch as a fuel source because they lack the enzyme to break it down.

B. Starch and glycogen are broken down starting at the outer branches.

C. When starch and glycogen are broken down for energy production, glucose residues are removed from the reducing end.

D. Glucose residues in starch and glycogen are removed in a spontaneous condensation reaction.

9. In starch and glycogen, the glucose monomers are joined by (1 4) linkages, whereas in cellulose, the glucose monomers are joined by (1 4) linkages. What is a biological consequence of this difference in sugar linkage?

A. Cellulose is generally not digestible by animals, whereas starch is easily digestible.

B. Cellulose takes on a helical structure and starch forms fibers.

C. Starch has more tensile strength than cellulose.

D. Glycogen is unbranched, while cellulose is highly branched.

10. Lectins are

A. Carbohydrates that can bind a protein

B. Proteins linked to carbohydrates.

C. Proteins that bind carbohydrates.

D. The oligosaccharide moieties on glycoproteins.

5. Which of the following is a structural polysaccharide in plant cells?

A. glycogen

B. amylose

C. starch

D. cellulose

6. Which of the following is true about proteoglycans?

A. They are small in size.

B. They are present in the extracellular matrix.

C. They comprise the cell wall of gram-positive bacteria.

D. They are glycolipids.

1. What is the nomenclature for the fatty acid shown below?

A. 20:8(Δ5,6,8,9,11,12,14,15)

B. 20:8(Δ6,7,9,10,12,13,15,16)

C. 20:4(Δ5,8,11,14)

D. 20:4(Δ6,9,12,15)

3. Which of the following lipids is used for energy storage?

A. glycolipids

B. glycerophospholipids

C. sphingolipids

D. triacylglycerols

4. Compared to olive oil, beef fat is has a higher proportion of

A. long-chain unsaturated fatty acids

B. long-chain saturated fatty acids.

C. short-chain unsaturated fatty acids.

D. short-chain saturated fatty acids.

5. When separating a mixture of lipids by adsorption chromatography, which lipid is likely to come out of the column first (the least likely to be retained)?

A. A glycolipid

B. A triacylglycerol

C. A glycerophospholipid

D. A sphingolipid

6. Which of the following is not true about sterols?

A. Sterols are structural lipids found in membranes

B. Only eukaryotes can synthesize their own sterols.

C. The fat-soluble vitamins are sterols

D. Cholesterol is a sterol.

7. What is the structure of the steroid nucleus found on all sterols?

A. It consists of five fused rings, four with six carbons and one with five.

B. It consists of three fused rings, two with six carbons and one with five.

C. It consists of five fused rings, three with six carbons and two with five.

D. It consists of four fused rings, three with six carbons and one with five.

8. Which statement is true about the difference between fats and sugars as a source of stored energy?

A. Sugars yield more energy than fats.

B. The human body can store sugars much longer than fats.

C. Sugars are a quicker source of energy because they are more soluble in water.

D. Fats are stored with more water than sugars.

9. Which of the following is true about vitamin D3 (cholecalciferol)?

A. It is a sterol.

B. It is a hormone precursor.

C. Humans synthesize their own Vitamin D3.

D. It is converted into a biologically active form by UV light from sunlight.

10. Which of the following methods would be best in order to distinguish between two fatty acids with similar lengthbut that are unsaturated at different positions?

A. Mass spectrometry

B. gas-liquid chromatography

C. Susceptibility to specific degradation

D. Adsorption chromatography

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