Question 1

Which of these natural amino acids,when present in a polypeptide,is not likely to exhibit significant hydrogen bonding through its side chain?

Accepted Answer

A) Leucine 
B) Threonine 
C) Tyrosine 
D) Serine 
E) All of these are likely to exhibit significant hydrogen bonding through the side chain. 
A) Leucine 
B) Threonine 
C) Tyrosine 
D) Serine 
E) All of these are likely to exhibit significant hydrogen bonding through the side chain. A

Question 2

Draw the structures of the following amino acids as they would appear in solution of pH = 3.
a)lysine,
b)glutamic acid,
c)alanine,
d)glycine.

Accepted Answer

The answer of Draw the structures of the following amino...

Question 3

Which of these natural amino acids contains a pyrrolidine ring?

Accepted Answer

A) Phenylalanine 
B) Tyrosine 
C) Tryptophan 
D) 4-Hydroxyproline 
E) Serine 
A) Phenylalanine 
B) Tyrosine 
C) Tryptophan 
D) 4-Hydroxyproline 
E) Serine D

Question 4

What is the induced fit in an enzyme?

Accepted Answer

A) It is the formation of hydrogen bonding between the enzyme and substrate. 
B) It is a change of secondary structure of the enzyme before binding the substrate. 
C) It is a conformational change produced upon binding of the substrate. 
D) It is a change in quaternary structure of the enzyme to produce the catalysis. 
E) It is the change in the substrate after the catalytic reaction took place. 
A) It is the formation of hydrogen bonding between the enzyme and substrate. 
B) It is a change of secondary structure of the enzyme before binding the substrate. 
C) It is a conformational change produced upon binding of the substrate. 
D) It is a change in quaternary structure of the enzyme to produce the catalysis. 
E) It is the change in the substrate after the catalytic reaction took place.

Question 5

Show the structures of the products obtained on reaction of valine with ninhydrin.

Accepted Answer

The answer of Show the structures of the products obtained...

Question 6

Which amino acid would not have its isoelectric point in the pH range 5-7?

Accepted Answer

A) Leucine 
B) Threonine 
C) Methionine 
D) Arginine 
E) Cysteine 
A) Leucine 
B) Threonine 
C) Methionine 
D) Arginine 
E) Cysteine

Question 7

Peptide synthesis has four basic steps.These are: ___.

Accepted Answer

protect the N-terminus,activat

Question 8

Why is dicyclohexylcarbodiimide (DCC)used in peptide synthesis?

Accepted Answer

A) DCC "protects" the amino group of the intended N-terminal amino acid. 
B) DCC activates the carboxyl group of one amino acid so that this amino acid reacts more readily with a second amino acid. 
C) DCC cleaves the blocking groups from the final peptide. 
D) DCC is the resin used in the automated synthesis of peptides. 
E) DCC removes the peptide from the resin at the conclusion of the synthesis. 
A) DCC "protects" the amino group of the intended N-terminal amino acid. 
B) DCC activates the carboxyl group of one amino acid so that this amino acid reacts more readily with a second amino acid. 
C) DCC cleaves the blocking groups from the final peptide. 
D) DCC is the resin used in the automated synthesis of peptides. 
E) DCC removes the peptide from the resin at the conclusion of the synthesis.

Question 9

What might be concluded upon determining that an unknown amino acid has its isoelectric point near pH 3?

Accepted Answer

A) It must have a hydrophobic side chain. 
B) It must have a hydrophilic side chain. 
C) Its side chain must contain a basic group. 
D) Its side chain must contain more acidic groups then basic groups. 
E) None of these choices is a valid conclusion. 
A) It must have a hydrophobic side chain. 
B) It must have a hydrophilic side chain. 
C) Its side chain must contain a basic group. 
D) Its side chain must contain more acidic groups then basic groups. 
E) None of these choices is a valid conclusion.

Question 10

What might be concluded upon determining that an unknown amino acid has its isoelectric point near pH 10?

Accepted Answer

A) It must have a hydrophobic side chain. 
B) It must have a hydrophilic side chain. 
C) Its side chain must contain more basic groups then acidic groups. 
D) Its side chain must contain an acidic group. 
E) None of these choices is a valid conclusion. 
A) It must have a hydrophobic side chain. 
B) It must have a hydrophilic side chain. 
C) Its side chain must contain more basic groups then acidic groups. 
D) Its side chain must contain an acidic group. 
E) None of these choices is a valid conclusion.

Question 11

Logically,the following "unnatural" amino acid would be substituted for which natural amino acid in the synthesis of peptide analogs?

Accepted Answer

A) Leucine 
B) Lysine 
C) Arginine 
D) Alanine 
E) Valine 
A) Leucine 
B) Lysine 
C) Arginine 
D) Alanine 
E) Valine

Question 12

Which of these amino acids has the R configuration at the stereogenic center but,nonetheless,is an L amino acid?

Accepted Answer

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

Question 13

The 22 $\alpha$-amino acids can be subdivided into three different types on the basis of the structures of their side chains.These three types are: ___.

Accepted Answer

neutral,ac

Question 14

What type of column chromatography packing is commonly used to separate amino acids by HPLC?

Accepted Answer

Cation-exc

Question 15

Which attractive force is responsible for maintaining the tertiary structure of a protein?

Accepted Answer

A) Disulfide linkages 
B) Hydrogen bonds 
C) van der Waals forces 
D) Hydrophobic interactions 
E) All of these choices. 
A) Disulfide linkages 
B) Hydrogen bonds 
C) van der Waals forces 
D) Hydrophobic interactions 
E) All of these choices.

Question 16

How many different tripeptides can exist,each containing one residue of glycine,one of l-threonine,and one of l-arginine?

Accepted Answer

A) 2 
B) 3 
C) 6 
D) 8 
E) 9 
A) 2 
B) 3 
C) 6 
D) 8 
E) 9

Question 17

Amino acids can be prepared from aldehydes by treatment with ammonia and HCN followed by hydrolysis.This method is known as the ___.

Accepted Answer

The answer of Amino acids can be prepared from aldehydes...

Question 18

The hormone that regulates glucose metabolism is called ___.Deficiency of this hormone is the major cause of ___.

Accepted Answer

The answer of The hormone that regulates glucose metabolism is...

Question 19

Which amino acid of a polypeptide would become labeled when the polypeptide is treated with 2,4-dinitrofluorobenzene in base,even though the amino acid is not a terminal amino acid?

Accepted Answer

A) Lysine 
B) Glycine 
C) Alanine 
D) Phenylalanine 
E) Leucine 
A) Lysine 
B) Glycine 
C) Alanine 
D) Phenylalanine 
E) Leucine

Question 20

Which of these are methods to determine the sequence of amino acids in a peptide?

Accepted Answer

A) Ladder sequencing; partial hydrolysis and sequence comparison. 
B) Partial hydrolysis; tandem mass spectrometry and IR. 
C) Partial hydrogenolysis and mass spectrometry. 
D) Edman's degradation and NMR. 
E) DNFB in acid,Edman's degradation and labeling. 
A) Ladder sequencing; partial hydrolysis and sequence comparison. 
B) Partial hydrolysis; tandem mass spectrometry and IR. 
C) Partial hydrogenolysis and mass spectrometry. 
D) Edman's degradation and NMR. 
E) DNFB in acid,Edman's degradation and labeling.

Exam 24: Amino Acids and Proteins

Which of these natural amino acids,when present in a polypeptide,is not likely to exhibit significant hydrogen bonding through its side chain?

Draw the structures of the following amino acids as they would appear in solution of pH = 3. a)lysine, b)glutamic acid, c)alanine, d)glycine.

Which of these natural amino acids contains a pyrrolidine ring?

What is the induced fit in an enzyme?

Show the structures of the products obtained on reaction of valine with ninhydrin.

Which amino acid would not have its isoelectric point in the pH range 5-7?

Peptide synthesis has four basic steps.These are: ___.

Why is dicyclohexylcarbodiimide (DCC)used in peptide synthesis?

What might be concluded upon determining that an unknown amino acid has its isoelectric point near pH 3?

What might be concluded upon determining that an unknown amino acid has its isoelectric point near pH 10?

Logically,the following "unnatural" amino acid would be substituted for which natural amino acid in the synthesis of peptide analogs?

Which of these amino acids has the R configuration at the stereogenic center but,nonetheless,is an L amino acid?

The 22 α\alphaα -amino acids can be subdivided into three different types on the basis of the structures of their side chains.These three types are: ___.

What type of column chromatography packing is commonly used to separate amino acids by HPLC?

Which attractive force is responsible for maintaining the tertiary structure of a protein?

How many different tripeptides can exist,each containing one residue of glycine,one of l-threonine,and one of l-arginine?

Amino acids can be prepared from aldehydes by treatment with ammonia and HCN followed by hydrolysis.This method is known as the ___.

The hormone that regulates glucose metabolism is called ___.Deficiency of this hormone is the major cause of ___.

Which amino acid of a polypeptide would become labeled when the polypeptide is treated with 2,4-dinitrofluorobenzene in base,even though the amino acid is not a terminal amino acid?

Which of these are methods to determine the sequence of amino acids in a peptide?

The Basics

Families of Carbon

Acids and Bases

Nomenclature and Conformations of Alkanes and Cycloalkanes

Stereochemistry

Nucleophilic Reactions

Alkenes and Alkynes I

Alkenes and Alkynes II

Nuclear Magnetic Resonance and Mass Spectrometry

Radical Reactions

Alcohols and Ethers

Alcohols From Carbonyl Compounds

Conjugated Unsaturated Systems

Aromatic Compounds

Reactions of Aromatic Compounds

Aldehydes and Ketones

Carboxylic Acids and Their Derivatives

Reactions at the Α Carbon of Carbonyl Compounds

Condensation and Conjugate Addition Reactions of Carbonyl Compounds

Amines

Transition Metal Complexes

Carbohydrates

Lipids

Nucleic Acids and Protein Synthesis

Filters

The 22 $\alpha$ -amino acids can be subdivided into three different types on the basis of the structures of their side chains.These three types are: ___.

The hormone that regulates glucose metabolism is called _.Deficiency of this hormone is the major cause of _.