Question 1

Provide the structure of the tripeptide glu-ser-ala at pH 2.

Accepted Answer

The answer of Provide the structure of the tripeptide glu-ser-ala...

Question 2

Draw structures for the forms of glycine present in basic,neutral,and acidic solutions.

Accepted Answer

+ + H₂N-CH₂-COO- H₃N-CH

Question 3

Give the product for the following reaction.

Accepted Answer

A) alanine 
B) leucine 
C) valine 
D) isoleucine 
E) glycine 
A) alanine 
B) leucine 
C) valine 
D) isoleucine 
E) glycine

Question 4

What is an amino acid analyzer?

Accepted Answer

An instrument that automates ion-exchang

Question 5

Rank the following amino acids in order of time of elution from a cation-exchange resin and a buffer pH of 4.0: aspartic acid,phenylalanine,arginine,and alanine.

Accepted Answer

aspartic acid > alan

Question 6

What is the major force responsible for the formation of an α-helix in protein secondary structure?

Accepted Answer

The answer of What is the major force responsible for...

Question 7

What is the major organic product of the following reaction?

Accepted Answer

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

Question 8

In peptide synthesis,give the use of di-tert-butyl dicarbonate.

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 9

Which of the following may characterize the secondary structure of proteins?

Accepted Answer

A) conformation of the protein backbone 
B) α-Helix 
C) parallel β-pleated sheet 
D) anti-parallel β-pleated sheet 
E) all of the above 
A) conformation of the protein backbone 
B) α-Helix 
C) parallel β-pleated sheet 
D) anti-parallel β-pleated sheet 
E) all of the above

Question 10

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

Accepted Answer

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

Question 11

What is electrophoresis?

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 12

Draw the form in which glutamate exists at pH = 0.

Accepted Answer

At pH = 0,

Question 13

Which of the following terms best describes the side chain of valine?

Accepted Answer

A) acidic 
B) basic 
C) charged,polar 
D) uncharged,polar 
E) nonpolar 
A) acidic 
B) basic 
C) charged,polar 
D) uncharged,polar 
E) nonpolar

Question 14

Give the product for the following reaction.

Accepted Answer

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

Question 15

In a globular protein,would the side chain of isoleucine most probably be oriented toward the interior of the protein or outward toward the aqueous surroundings? Explain.

Accepted Answer

The isoleucine side chain is a nonpolar

Question 16

Phenyl isothiocyanate (PITC)is commonly known as Edman's reagent.Edman's reagent is widely used to identify which of the following?

Accepted Answer

A) the number and kind of amino acids in the protein 
B) the disulfide bridges in the protein 
C) C-terminal amino acid of the protein 
D) N-terminal amino acid of the protein 
E) the number of peptide bonds in the protein 
A) the number and kind of amino acids in the protein 
B) the disulfide bridges in the protein 
C) C-terminal amino acid of the protein 
D) N-terminal amino acid of the protein 
E) the number of peptide bonds in the protein

Question 17

Which labeled bond in the following molecule is known as the peptide bond?

Accepted Answer

A) 1 
B) 2 
C) 3 
D) 4 
E) 5 
A) 1 
B) 2 
C) 3 
D) 4 
E) 5

Question 18

Which of the following is an acceptable name for the peptide sequence shown below? Glu-Glu-His-Val-Cys

Accepted Answer

A) 1,2-diglutamylhistidylvalylcysteine 
B) glutamylglutamylhistidylvalylcysteine 
C) 1-glutamyl-2-glutamylhistidylvalylcysteine 
D) diglutamylhistidylvalylcysteine 
E) biglutamylhistidylvalylcysteine 
A) 1,2-diglutamylhistidylvalylcysteine 
B) glutamylglutamylhistidylvalylcysteine 
C) 1-glutamyl-2-glutamylhistidylvalylcysteine 
D) diglutamylhistidylvalylcysteine 
E) biglutamylhistidylvalylcysteine

Question 19

How is the enzyme chymotrypsin used in peptide structure determination?

Accepted Answer

Chymotrypsin cleaves the peptide chain a

Question 20

Give the pH at which histidine exists in the following form.

Accepted Answer

A) 0 
B) 4 
C) 8 
D) 12 
E) 14 
A) 0 
B) 4 
C) 8 
D) 12 
E) 14

Exam 21: Amino Acids,peptides,and Proteins

Provide the structure of the tripeptide glu-ser-ala at pH 2.

Draw structures for the forms of glycine present in basic,neutral,and acidic solutions.

Give the product for the following reaction.

What is an amino acid analyzer?

Rank the following amino acids in order of time of elution from a cation-exchange resin and a buffer pH of 4.0: aspartic acid,phenylalanine,arginine,and alanine.

What is the major force responsible for the formation of an α-helix in protein secondary structure?

What is the major organic product of the following reaction?

In peptide synthesis,give the use of di-tert-butyl dicarbonate.

Which of the following may characterize the secondary structure of proteins?

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

What is electrophoresis?

Draw the form in which glutamate exists at pH = 0.

Which of the following terms best describes the side chain of valine?

Give the product for the following reaction.

In a globular protein,would the side chain of isoleucine most probably be oriented toward the interior of the protein or outward toward the aqueous surroundings? Explain.

Phenyl isothiocyanate (PITC)is commonly known as Edman's reagent.Edman's reagent is widely used to identify which of the following?

Which labeled bond in the following molecule is known as the peptide bond?

Which of the following is an acceptable name for the peptide sequence shown below? Glu-Glu-His-Val-Cys

How is the enzyme chymotrypsin used in peptide structure determination?

Give the pH at which histidine exists in the following form.

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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