Question 1

In a highly basic solution,pH = 13,the dominant form of glycine is:

Accepted Answer

A) NH2-CH2-COOH. 
B) NH2-CH2-COO-. 
C) NH2-CH3+-COO-. 
D) NH3+-CH2-COOH. 
E) NH3+-CH2-COO-. 
A) NH2-CH2-COOH. 
B) NH2-CH2-COO-. 
C) NH2-CH3+-COO-. 
D) NH3+-CH2-COOH. 
E) NH3+-CH2-COO-.

Question 2

How can isoelectric focusing be used in conjunction with SDS gel electrophoresis?

Accepted Answer

Isoelectric focusing can separate protei

Question 3

The amino acid histidine has a side chain for which the pKa is 6.0.Calculate what fraction of the histidine side chains will carry a positive charge at pH 5.4.Be sure to show your work.

Accepted Answer

@#IMG-DLM&

Therefore,at pH 5.

Question 4

As a protein is purified,both the amount of total protein and the activity of the purified protein decrease.Why,then,does the specific activity of the purified protein increase?

Accepted Answer

Specific activity is the units of enzyme

Question 5

The uncommon amino acid selenocysteine has an R group with the structure -CH2-SeH (pKa $\approx$  5).In an aqueous solution,pH = 7.0,selenocysteine would:

Accepted Answer

A) be a fully ionized zwitterion with no net charge. 
B) be found in proteins as d-selenocysteine. 
C) never be found in a protein. 
D) be nonionic. 
E) not be optically active. 
A) be a fully ionized zwitterion with no net charge. 
B) be found in proteins as d-selenocysteine. 
C) never be found in a protein. 
D) be nonionic. 
E) not be optically active.

Question 6

Which of the following statements about aromatic amino acids is correct?

Accepted Answer

A) All are strongly hydrophilic. 
B) Histidine's ring structure results in its being categorized as aromatic or basic,depending on pH. 
C) On a molar basis,tryptophan absorbs more ultraviolet light than tyrosine. 
D) The major contribution to the characteristic absorption of light at 280 nm by proteins is the phenylalanine R group. 
E) The presence of a ring structure in its R group determines whether or not an amino acid is aromatic. 
A) All are strongly hydrophilic. 
B) Histidine's ring structure results in its being categorized as aromatic or basic,depending on pH. 
C) On a molar basis,tryptophan absorbs more ultraviolet light than tyrosine. 
D) The major contribution to the characteristic absorption of light at 280 nm by proteins is the phenylalanine R group. 
E) The presence of a ring structure in its R group determines whether or not an amino acid is aromatic.

Question 7

Which of the following statements about cystine is correct?

Accepted Answer

A) Cystine forms when the -CH2-SH R group is oxidized to form a -CH2-S-S-CH2- disulfide bridge between two cysteines. 
B) Cystine is an example of a nonstandard amino acid,derived by linking two standard amino acids. 
C) Cystine is formed by the oxidation of the carboxylic acid group on cysteine. 
D) Cystine is formed through a peptide linkage between two cysteines. 
E) Two cystines are released when a -CH2-S-S-CH2- disulfide bridge is reduced to -CH2-SH. 
A) Cystine forms when the -CH2-SH R group is oxidized to form a -CH2-S-S-CH2- disulfide bridge between two cysteines. 
B) Cystine is an example of a nonstandard amino acid,derived by linking two standard amino acids. 
C) Cystine is formed by the oxidation of the carboxylic acid group on cysteine. 
D) Cystine is formed through a peptide linkage between two cysteines. 
E) Two cystines are released when a -CH2-S-S-CH2- disulfide bridge is reduced to -CH2-SH.

Question 8

In the amino acid glycine,what effect does the positively charged -NH3+ group have on the pKa of an amino acid's -COOH group?

Accepted Answer

The positively charged amino group stabi

Question 9

Only one of the common amino acids has no free $\alpha$-amino group.Name this amino acid and draw its structure.

Accepted Answer

The amino acid l-proline has n

Question 10

In a conjugated protein,a prosthetic group is:

Accepted Answer

A) a fibrous region of a globular protein. 
B) a nonidentical subunit of a protein with many identical subunits. 
C) a part of the protein that is not composed of amino acids. 
D) a subunit of an oligomeric protein. 
E) synonymous with "protomer." 
A) a fibrous region of a globular protein. 
B) a nonidentical subunit of a protein with many identical subunits. 
C) a part of the protein that is not composed of amino acids. 
D) a subunit of an oligomeric protein. 
E) synonymous with "protomer."

Question 11

An octapeptide composed of four repeating glycylalanyl units has:

Accepted Answer

A) one free amino group on an alanyl residue. 
B) one free amino group on an alanyl residue and one free carboxyl group on a glycyl residue. 
C) one free amino group on a glycyl residue and one free carboxyl group on an alanyl residue. 
D) two free amino and two free carboxyl groups. 
E) two free carboxyl groups,both on glycyl residues. 
A) one free amino group on an alanyl residue. 
B) one free amino group on an alanyl residue and one free carboxyl group on a glycyl residue. 
C) one free amino group on a glycyl residue and one free carboxyl group on an alanyl residue. 
D) two free amino and two free carboxyl groups. 
E) two free carboxyl groups,both on glycyl residues.

Question 12

What are the structural characteristics common to all amino acids found in naturally occurring proteins?

Accepted Answer

All amino acids found in naturally occur

In a highly basic solution,pH = 13,the dominant form of glycine is:

How can isoelectric focusing be used in conjunction with SDS gel electrophoresis?

The amino acid histidine has a side chain for which the pK_a is 6.0.Calculate what fraction of the histidine side chains will carry a positive charge at pH 5.4.Be sure to show your work.

As a protein is purified,both the amount of total protein and the activity of the purified protein decrease.Why,then,does the specific activity of the purified protein increase?

The uncommon amino acid selenocysteine has an R group with the structure -CH₂-SeH (pK_a $\approx$ 5).In an aqueous solution,pH = 7.0,selenocysteine would:

Which of the following statements about aromatic amino acids is correct?

Which of the following statements about cystine is correct?

In the amino acid glycine,what effect does the positively charged -NH₃⁺ group have on the pK_a of an amino acid's -COOH group?

Only one of the common amino acids has no free $\alpha$ -amino group.Name this amino acid and draw its structure.

In a conjugated protein,a prosthetic group is:

An octapeptide composed of four repeating glycylalanyl units has:

What are the structural characteristics common to all amino acids found in naturally occurring proteins?

The Foundations of Biochemistry

Water

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Biosignaling

Principles of Bioenergetics

Glycolysis, gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, nucleotides, and Related Molecules

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Exam 3: Amino Acids, peptides, and Proteins

In a highly basic solution,pH = 13,the dominant form of glycine is:

How can isoelectric focusing be used in conjunction with SDS gel electrophoresis?

The amino acid histidine has a side chain for which the pKa is 6.0.Calculate what fraction of the histidine side chains will carry a positive charge at pH 5.4.Be sure to show your work.

As a protein is purified,both the amount of total protein and the activity of the purified protein decrease.Why,then,does the specific activity of the purified protein increase?

The uncommon amino acid selenocysteine has an R group with the structure -CH2-SeH (pKa ≈\approx≈ 5).In an aqueous solution,pH = 7.0,selenocysteine would:

Which of the following statements about aromatic amino acids is correct?

Which of the following statements about cystine is correct?

In the amino acid glycine,what effect does the positively charged -NH3+ group have on the pKa of an amino acid's -COOH group?

Only one of the common amino acids has no free α\alphaα -amino group.Name this amino acid and draw its structure.

In a conjugated protein,a prosthetic group is:

An octapeptide composed of four repeating glycylalanyl units has:

What are the structural characteristics common to all amino acids found in naturally occurring proteins?

The Foundations of Biochemistry

Water

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Biosignaling

Principles of Bioenergetics

Glycolysis, gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, nucleotides, and Related Molecules

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

The amino acid histidine has a side chain for which the pK_a is 6.0.Calculate what fraction of the histidine side chains will carry a positive charge at pH 5.4.Be sure to show your work.

The uncommon amino acid selenocysteine has an R group with the structure -CH₂-SeH (pK_a $\approx$ 5).In an aqueous solution,pH = 7.0,selenocysteine would:

In the amino acid glycine,what effect does the positively charged -NH₃⁺ group have on the pK_a of an amino acid's -COOH group?

Only one of the common amino acids has no free $\alpha$ -amino group.Name this amino acid and draw its structure.