Question 1

The overall shape of a protein is greatly influenced by

Accepted Answer

A) amino acid R group properties. 
B) charged amino acids. 
C) hydrophobic amino acids. 
D) pH. 
E) hydrophilic amino acids. 
A) amino acid R group properties. 
B) charged amino acids. 
C) hydrophobic amino acids. 
D) pH. 
E) hydrophilic amino acids.

Question 2

Match the following to their functions.
-21st amino acid in many species

Accepted Answer

A) N-formylmethionine 
B) Histamine 
C) S-adenosylmethionine 
D) g-aminobutyrate 
E) selenocysteine
F)epinephrine (adrenaline) 
A) N-formylmethionine 
B) Histamine 
C) S-adenosylmethionine 
D) g-aminobutyrate 
E) selenocysteine
F)epinephrine (adrenaline)

Question 3

The isoelectric point of alanine is pH = 6.15.It is mixed with proline (pHCOOH = 2.0;pHNH₂ = 10.6),and the mixture is placed in an electric field at pH 6.15.Which statement is true?

Accepted Answer

A) The two amino acids will be separated. 
B) The two amino acids will not be separated. 
C) Neither amino acid will move in the electric field. 
D) Both amino acids will move from the origin and be separated. 
A) The two amino acids will be separated. 
B) The two amino acids will not be separated. 
C) Neither amino acid will move in the electric field. 
D) Both amino acids will move from the origin and be separated.

Question 4

What is the net charge on the tripeptide Gly-Arg-Lys at pH 7? The table below gives the pKa's of the ionizable groups on the free amino acids.

Accepted Answer

A) -1 
B) 0 
C) +1 
D) +2 
A) -1 
B) 0 
C) +1 
D) +2

Question 5

Proline is distinct among the 20 commonly found amino acids because

Accepted Answer

A) it is a ring compound. 
B) it is hydrophilic and ionic. 
C) the nitrogen of the amino group is in a ring. 
D) the carbon of the carboxyl group is in a ring. 
E) it has little effect on protein structure. 
A) it is a ring compound. 
B) it is hydrophilic and ionic. 
C) the nitrogen of the amino group is in a ring. 
D) the carbon of the carboxyl group is in a ring. 
E) it has little effect on protein structure.

Question 6

Ammonium sulfate is often used as a first step in protein purification because it

Accepted Answer

A) buffers solutions and protects the protein. 
B) precipitates many proteins. 
C) precipitates all proteins. 
D) hydrolyzes proteins into their constituent amino acids. 
A) buffers solutions and protects the protein. 
B) precipitates many proteins. 
C) precipitates all proteins. 
D) hydrolyzes proteins into their constituent amino acids.

Question 7

Amino acids with non-ionizable side chains are zwitterions when they are ________.

Accepted Answer

A) in any solution 
B) at physiological pH,pH = 7.4 
C) in acidic solutions only 
D) in alkaline solutions only 
E) All of the above 
A) in any solution 
B) at physiological pH,pH = 7.4 
C) in acidic solutions only 
D) in alkaline solutions only 
E) All of the above

Question 8

Cation-exchange resins have negatively charged groups covalently attached to the column matrix.

Accepted Answer

A) True 
 B)False

Question 9

Which technique is used less for protein purification and more for the determination of molecular weights?

Accepted Answer

A) Affinity chromatography. 
B) SDS-PAGE. 
C) Gel filtration. 
D) Ion exchange chromatography. 
A) Affinity chromatography. 
B) SDS-PAGE. 
C) Gel filtration. 
D) Ion exchange chromatography.

Question 10

If the R group of an amino acid is -CH₃,then the name of this compound is

Accepted Answer

A) methyl amino acid. 
B) 2-aminopropanoic acid. 
C) alanine. 
D) All of the above. 
E) B and C. 
A) methyl amino acid. 
B) 2-aminopropanoic acid. 
C) alanine. 
D) All of the above. 
E) B and C.

Question 11

Amino acids and amino acid derivatives can be used to modify proteins.

Accepted Answer

A) True 
 B)False

Question 12

For the amino acid lysine,the Henderson-Hasselbalch equation can be applied to ________ ionization group(s).

Accepted Answer

A) one 
B) two 
C) three 
D) four 
A) one 
B) two 
C) three 
D) four

Question 13

The liquid that emerges from the bottom of a chromatographic column is called the supernatant.

Accepted Answer

A) True 
 B)False

Question 14

An enzyme works well at as a catalyst at a pH of 7.2.It is found that catalytic activity is significantly less at a pH of 8.4.Which could likely cause the decrease in activity?

Accepted Answer

A) The protein has been degraded into its amino acids at pH 8.4. 
B) The protein has changed shape due to a change in charge. 
C) The protonation state of amino acids involved in the catalytic mechanism has changed. 
D) B and C above. 
E) All of the above. 
A) The protein has been degraded into its amino acids at pH 8.4. 
B) The protein has changed shape due to a change in charge. 
C) The protonation state of amino acids involved in the catalytic mechanism has changed. 
D) B and C above. 
E) All of the above.

Question 15

If two proteins are determined to have descended from a common ancestor they are

Accepted Answer

A) heterogeneous. 
B) amphipathic. 
C) taxolinked. 
D) homologous. 
A) heterogeneous. 
B) amphipathic. 
C) taxolinked. 
D) homologous.

Question 16

What is the purpose of SDS in SDS-PAGE?

Accepted Answer

A) To selectively bind the target protein. 
B) To maintain buffer pH in the gel. 
C) To cause the separation to be on the basis of molecular weight only. 
D) To initiate polymerization of acrylamide to form a gel. 
A) To selectively bind the target protein. 
B) To maintain buffer pH in the gel. 
C) To cause the separation to be on the basis of molecular weight only. 
D) To initiate polymerization of acrylamide to form a gel.

Question 17

The pKa's of arginine's α-Carboxyl group,α-Amino group and side chain are 1.8,9.0 and 12.5,respectively.Calculate the isoelectric point.

Accepted Answer

A) 7.8 
B) 7.2 
C) 10.8 
D) 5.4 
A) 7.8 
B) 7.2 
C) 10.8 
D) 5.4

Question 18

Cystine is likely to be isolated from proteins that are

Accepted Answer

A) high in methionine. 
B) in the cell nucleus. 
C) intracellular. 
D) extracellular. 
A) high in methionine. 
B) in the cell nucleus. 
C) intracellular. 
D) extracellular.

Question 19

A sequence of amino acids with a relatively high hydropathy is very likely to function by

Accepted Answer

A) being at the active site of an enzyme. 
B) being embedded in a cell membrane. 
C) making a protein soluble. 
D) being on the protein surface. 
A) being at the active site of an enzyme. 
B) being embedded in a cell membrane. 
C) making a protein soluble. 
D) being on the protein surface.

Question 20

The primary structure of a protein specifically describes the ________.

Accepted Answer

A) location of disulfide bonds 
B) linear sequence of amino acids 
C) overall three-dimensional shape 
D) Φ and Ψ angles for each amino acid 
A) location of disulfide bonds 
B) linear sequence of amino acids 
C) overall three-dimensional shape 
D) Φ and Ψ angles for each amino acid

Exam 3: Amino Acids and the Primary Structures of Proteins

The overall shape of a protein is greatly influenced by

Match the following to their functions. -21st amino acid in many species

The isoelectric point of alanine is pH = 6.15.It is mixed with proline (pHCOOH = 2.0;pHNH₂ = 10.6),and the mixture is placed in an electric field at pH 6.15.Which statement is true?

What is the net charge on the tripeptide Gly-Arg-Lys at pH 7? The table below gives the pKa's of the ionizable groups on the free amino acids.

Proline is distinct among the 20 commonly found amino acids because

Ammonium sulfate is often used as a first step in protein purification because it

Amino acids with non-ionizable side chains are zwitterions when they are ________.

Cation-exchange resins have negatively charged groups covalently attached to the column matrix.

Which technique is used less for protein purification and more for the determination of molecular weights?

If the R group of an amino acid is -CH₃,then the name of this compound is

Amino acids and amino acid derivatives can be used to modify proteins.

For the amino acid lysine,the Henderson-Hasselbalch equation can be applied to ________ ionization group(s).

The liquid that emerges from the bottom of a chromatographic column is called the supernatant.

An enzyme works well at as a catalyst at a pH of 7.2.It is found that catalytic activity is significantly less at a pH of 8.4.Which could likely cause the decrease in activity?

If two proteins are determined to have descended from a common ancestor they are

What is the purpose of SDS in SDS-PAGE?

The pKa's of arginine's α-Carboxyl group,α-Amino group and side chain are 1.8,9.0 and 12.5,respectively.Calculate the isoelectric point.

Cystine is likely to be isolated from proteins that are

A sequence of amino acids with a relatively high hydropathy is very likely to function by

The primary structure of a protein specifically describes the ________.

Introduction to Biochemistry

Water

Proteins: Three-Dimensional Structure and Function

Properties of Enzymes

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Glycolysis

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

The Citric Acid Cycle

Electron Transport and Atp Synthesis

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

DNA Replication, repair, and Recombination

Transcription and RNA Processing

Protein Synthesis

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