Question 1

What is thin-layer chromatography?

Accepted Answer

A) a technique that separates amino acids on the basis of their polarity 
B) a technique that separates amino acids on the basis of their solubility in water 
C) a technique that separates amino acids on the basis of their pI values 
D) a technique that separates amino acids on the basis of pKa of α-COOH values 
E) a technique that separates amino acids on the basis of pKa of α-+NH3 values 
A) a technique that separates amino acids on the basis of their polarity 
B) a technique that separates amino acids on the basis of their solubility in water 
C) a technique that separates amino acids on the basis of their pI values 
D) a technique that separates amino acids on the basis of pKa of α-COOH values 
E) a technique that separates amino acids on the basis of pKa of α-+NH3 values

Question 2

Which of the following amino acids has the highest isoelectric point?

Accepted Answer

A) arginine 
B) aspartic acid 
C) glycine 
D) proline 
E) phenylalanine 
A) arginine 
B) aspartic acid 
C) glycine 
D) proline 
E) phenylalanine

Question 3

Identify the amino acid that is hydrolyzed by cyanogen bromide.

Accepted Answer

A) N-side of met 
B) C-side of gly 
C) C-side of met 
D) C-side of phe 
E) C-side of arg 
A) N-side of met 
B) C-side of gly 
C) C-side of met 
D) C-side of phe 
E) C-side of arg

Question 4

Provide the structure of the tripeptide val-gly-ser at pH 2.

Accepted Answer

The answer of Provide the structure of the tripeptide val-gly-ser...

Question 5

Provide the Fischer projection of L-aspartic acid.

Accepted Answer

The answer of Provide the Fischer projection of L-aspartic acid....

Question 6

What are enzymes?

Accepted Answer

A) saccharides that catalyze chemical reactions 
B) nucleic acids that catalyze chemical reactions 
C) unsaturated fats that catalyze chemical reactions 
D) DNA molecules that catalyze chemical reactions 
E) proteins that catalyze chemical reactions 
A) saccharides that catalyze chemical reactions 
B) nucleic acids that catalyze chemical reactions 
C) unsaturated fats that catalyze chemical reactions 
D) DNA molecules that catalyze chemical reactions 
E) proteins that catalyze chemical reactions

Question 7

Calculate the isoelectric point for the following compound.

Accepted Answer

A) 3)22 
B) 5)34 
C) 5)93 
D) 6)91 
E) 9)67 
A) 3)22 
B) 5)34 
C) 5)93 
D) 6)91 
E) 9)67

Question 8

Describe what a β-pleated sheet is and explain the difference between parallel and anti-parallel β-pleated sheets.

Accepted Answer

A β-pleated sheet is a type of secondary

Question 9

In peptide synthesis,give the use of dicyclohexylcarbodiimide.

Accepted Answer

A) activates the carboxyl group of an amino acid 
B) protects the carboxyl group of an amino acid 
C) protects the amino group of an amino acid 
D) activates the amino group of an amino acid 
E) removes the protecting group on the N-terminal amino acid 
A) activates the carboxyl group of an amino acid 
B) protects the carboxyl group of an amino acid 
C) protects the amino group of an amino acid 
D) activates the amino group of an amino acid 
E) removes the protecting group on the N-terminal amino acid

Question 10

What is the net charge of arginine in a solution of pH 1.0?

Accepted Answer

The answer of What is the net charge of arginine...

Question 11

Draw glutamate.

Accepted Answer

The answer of Draw glutamate....

Question 12

A decapeptide undergoes partial hydrolysis to give peptides whose amino acids are shown below.Reaction of the decapeptide with Edman's reagent releases PTH-leu.What is the sequence of the decapeptide? (1)Pro,Ser (5)Glu,Ser,Val,Pro
(2)Gly,Gly (6)Glu,Pro,Gly
(3)Met,Ala,Leu (7)Met,Leu
(4)Gly,Ala (8)His,Val

Accepted Answer

A) Leu-Met-Ala-Gly-Gly-Glu-Pro-Ser-His-Val 
B) Leu-Met-Ala-Gly-Gly-Glu-Ser-Pro-Val-His 
C) Leu-Ala-Met-Gly-Gly-Glu-Pro-Ser-Val-His 
D) Leu-Met-Gly-Ala-Gly-Glu-Pro-Ser-Val-His 
E) Leu-Met-Ala-Gly-Gly-Glu-Pro-Ser-Val-His 
A) Leu-Met-Ala-Gly-Gly-Glu-Pro-Ser-His-Val 
B) Leu-Met-Ala-Gly-Gly-Glu-Ser-Pro-Val-His 
C) Leu-Ala-Met-Gly-Gly-Glu-Pro-Ser-Val-His 
D) Leu-Met-Gly-Ala-Gly-Glu-Pro-Ser-Val-His 
E) Leu-Met-Ala-Gly-Gly-Glu-Pro-Ser-Val-His

Question 13

Name the following compound.

Accepted Answer

A) cysteine 
B) threonine 
C) methionine 
D) serine 
E) asparagine 
A) cysteine 
B) threonine 
C) methionine 
D) serine 
E) asparagine

Question 14

You are given a mixture that contains glutamic acid (pI = 3.2),arginine (pI = 10.8),and valine (pI = 6.0),and you subject the mixture to electrophoresis.
a)Which amino acids migrate toward the cathode when the electrophoresis is carried out at a pH of 7.1?
b)Which amino acids migrate toward the anode when the electrophoresis is carried out at a pH of 7.1?
c)Which amino acid migrates farthest toward the anode at a pH of 7.1?
d)Since amino acids themselves are colorless,how is the separation of amino acids after electrophoresis detected?

Accepted Answer

a)arginine. b)valine and gluta

Question 15

Which type of protein,globular or fibrous,tends to function primarily as structural parts of an organism?

Accepted Answer

The answer of Which type of protein,globular or fibrous,tends to...

Question 16

Draw the predominant form of histidine at pH=0.

Accepted Answer

The answer of Draw the predominant form of histidine at...

Question 17

Which of the following is a zwitterion?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 18

In peptide synthesis,give the use of trifluoroacetic acid.

Accepted Answer

A) activates the carboxyl group of an amino acid 
B) protects the carboxyl group of an amino acid 
C) protects the amino group of an amino acid 
D) activates the amino group of an amino acid 
E) removes the protecting group on the N-terminal amino acid 
A) activates the carboxyl group of an amino acid 
B) protects the carboxyl group of an amino acid 
C) protects the amino group of an amino acid 
D) activates the amino group of an amino acid 
E) removes the protecting group on the N-terminal amino acid

Question 19

Which of the following amino acids will be retained longest in the column when separated by cation-exchange chromatography?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 20

The monomeric units that make up peptides and protein polymers are

Accepted Answer

A) nucleic acids 
B) amino acids 
C) oligosaccharides 
D) amylopectins 
E) celluloses 
A) nucleic acids 
B) amino acids 
C) oligosaccharides 
D) amylopectins 
E) celluloses

Exam 21: Amino Acids,peptides,and Proteins

What is thin-layer chromatography?

Which of the following amino acids has the highest isoelectric point?

Identify the amino acid that is hydrolyzed by cyanogen bromide.

Provide the structure of the tripeptide val-gly-ser at pH 2.

Provide the Fischer projection of L-aspartic acid.

What are enzymes?

Calculate the isoelectric point for the following compound.

Describe what a β-pleated sheet is and explain the difference between parallel and anti-parallel β-pleated sheets.

In peptide synthesis,give the use of dicyclohexylcarbodiimide.

What is the net charge of arginine in a solution of pH 1.0?

Draw glutamate.

Name the following compound.

Which type of protein,globular or fibrous,tends to function primarily as structural parts of an organism?

Draw the predominant form of histidine at pH=0.

Which of the following is a zwitterion?

In peptide synthesis,give the use of trifluoroacetic acid.

Which of the following amino acids will be retained longest in the column when separated by cation-exchange chromatography?

The monomeric units that make up peptides and protein polymers are

Remembering General Chemistry: Electronic Structure and Bonding

Acids and Bases: Central to Understanding Organic Chemistry

An Introduction to Organic Compounds: Nomenclature, physical Properties, and Structure

Isomers: the Arrangement of Atoms in Space

Alkenes: Structure,nomenclature,and an Introduction to Reactivity - Thermodynamics and Kinetics

The Reactions of Alkenes - the Stereochemistry of Addition Reactions

The Reactions of Alkynes - Introduction to Multistep Synthesis

Delocalized Electrons: Their Effect on Stability, pka, and the Products of a Reaction - Aromaticity and Electronic Effects: an Introduction to the Reactions of Benzene

Substitution and Elimination Reactions of Alkyl Halides

Reactions of Alcohols, ethers, epoxides, amines and Sulfur-Containing Compounds

Organometallic Compounds

Radicals

Mass Spectrometry,infrared Spectroscopy,and Uvvis Spectroscopy

Nmr Spectroscopy

Reactions of Carboxylic Acids and Carboxylic Acid Derivatives

Reactions of Aldehydes and Ketones

Reactions at the Α-Carbon

Reactions of Benzene and Substituted Benzenes

More About Amines - Reactions of Heterocylic Compounds

The Organic Chemistry of Carbohydrates

Catalysis in Organic Reactions and in Enzymatic Reactions

The Organic Chemistry of the Coenzymes, compounds Derived From Vitamins

The Organic Chemistry of the Metabolic Pathways

The Organic Chemistry of Lipids

The Chemistry of the Nucleic Acids

Synthetic Polymers

Pericyclic Reactions

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