Question 1

Which statement 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 2

When the ribosome forms a peptide bond, which two atoms form a covalent bond?

Accepted Answer

A)  the $\alpha$ carbon and the amino nitrogen 
B)  the amino nitrogen and carboxylic acid carbon 
C)  the$\alpha$ carbon and the carboxylic acid carbon 
D)  the amino nitrogen and the $\beta$carbon 
E)  It depends on the amino acids being joined. 
A)  the $\alpha$ carbon and the amino nitrogen 
B)  the amino nitrogen and carboxylic acid carbon 
C)  the$\alpha$ carbon and the carboxylic acid carbon 
D)  the amino nitrogen and the $\beta$carbon 
E)  It depends on the amino acids being joined.

Question 3

How can a polypeptide have only one free amino group and one free carboxyl group?

Accepted Answer

A polypeptide can have only one free ami

Question 4

A protein with a high percentage of lysine and arginine residues would be BEST purified and concentrated with which type of column?

Accepted Answer

A)  cation exchange 
B)  anion exchange 
C)  size-exclusion chromatography 
D)  affinity chromatography 
E)  reverse-phase chromatography 
A)  cation exchange 
B)  anion exchange 
C)  size-exclusion chromatography 
D)  affinity chromatography 
E)  reverse-phase chromatography

Question 5

Titration of valine by a strong base, for example NaOH, reveals two pK's. The titration reaction occurring at pK2 (pK2 = 9.62) is:

Accepted Answer

A)  -COOH + OH- $\rightarrow$ -COO- + H2O. 
B)  -COOH + -NH2 $\rightarrow$ -COO- + -NH2+. 
C)  -COO- + -NH2+ $\rightarrow$ -COOH + -NH2. 
D)  -NH3+ + OH- $\rightarrow$ -NH2 + H2O. 
E)  -NH2 + OH- $\rightarrow$ -NH- + H2O. 
A)  -COOH + OH- $\rightarrow$ -COO- + H2O. 
B)  -COOH + -NH2 $\rightarrow$ -COO- + -NH2+. 
C)  -COO- + -NH2+ $\rightarrow$ -COOH + -NH2. 
D)  -NH3+ + OH- $\rightarrow$ -NH2 + H2O. 
E)  -NH2 + OH- $\rightarrow$ -NH- + H2O.

Question 6

Two amino acids of the standard 20 contain sulfur atoms. They are:

Accepted Answer

A)  cysteine and serine. 
B)  cysteine and threonine. 
C)  methionine and cysteine 
D)  methionine and serine 
E)  threonine and serine. 
A)  cysteine and serine. 
B)  cysteine and threonine. 
C)  methionine and cysteine 
D)  methionine and serine 
E)  threonine and serine.

Question 7

Lys residues make up 10.5% of the weight of ribonuclease. The ribonuclease molecule contains 10 Lys residues. Calculate the molecular weight of ribonuclease.

Accepted Answer

To calculate the molecular weight of rib

Question 8

On the molecule below, the arrow is pointing to the _____ carbon.

Accepted Answer

A)  amino 
B)  $\alpha$ 
C)  $\beta$ 
D)  $\gamma$ 
E)  carboxylic acid 
A)  amino 
B)  $\alpha$ 
C)  $\beta$ 
D)  $\gamma$ 
E)  carboxylic acid

Question 9

A protein with a high percentage of aspartate and glutamate residues would be BEST purified and concentrated with which type of column?

Accepted Answer

A)  cation exchange 
B)  anion exchange 
C)  size-exclusion chromatography 
D)  affinity chromatography 
E)  reverse-phase chromatography 
A)  cation exchange 
B)  anion exchange 
C)  size-exclusion chromatography 
D)  affinity chromatography 
E)  reverse-phase chromatography

Question 10

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

To calculate the fraction of histidine s

Question 11

R. Bruce Merrifield provided an innovation to synthesize peptides. Which statement does NOT describe part of his technology?

Accepted Answer

A)  One end of the peptide is attached to a solid support. 
B)  At each step in the cycle, protective chemical groups block unwanted reactions. 
C)  The peptide product must be purified between each step of the cycle. 
D)  The support for the peptides is similar to a chromatography column. 
E)  All of the statements describe part of Merrifield's technology. 
A)  One end of the peptide is attached to a solid support. 
B)  At each step in the cycle, protective chemical groups block unwanted reactions. 
C)  The peptide product must be purified between each step of the cycle. 
D)  The support for the peptides is similar to a chromatography column. 
E)  All of the statements describe part of Merrifield's technology.

Question 12

At pH 7.0, converting a proline to hydroxyproline, will have what effect on the overall charge of the protein containing it?

Accepted Answer

A)  It will become more negative 
B)  It will become more positive. 
C)  It will stay the same. 
D)  There is not enough information to answer the question. 
E)  The answer depends on the salt concentration. 
A)  It will become more negative 
B)  It will become more positive. 
C)  It will stay the same. 
D)  There is not enough information to answer the question. 
E)  The answer depends on the salt concentration.

Which statement about aromatic amino acids is CORRECT?

When the ribosome forms a peptide bond, which two atoms form a covalent bond?

How can a polypeptide have only one free amino group and one free carboxyl group?

A protein with a high percentage of lysine and arginine residues would be BEST purified and concentrated with which type of column?

Titration of valine by a strong base, for example NaOH, reveals two pK's. The titration reaction occurring at pK₂ (pK₂ = 9.62) is:

Two amino acids of the standard 20 contain sulfur atoms. They are:

Lys residues make up 10.5% of the weight of ribonuclease. The ribonuclease molecule contains 10 Lys residues. Calculate the molecular weight of ribonuclease.

On the molecule below, the arrow is pointing to the _____ carbon.

A protein with a high percentage of aspartate and glutamate residues would be BEST purified and concentrated with which type of column?

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.

R. Bruce Merrifield provided an innovation to synthesize peptides. Which statement does NOT describe part of his technology?

At pH 7.0, converting a proline to hydroxyproline, will have what effect on the overall charge of the protein containing it?

The Foundations of Biochemistry

Water

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Bioenergetics and Biochemical Reaction Types

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

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Exam 3: Amino Acids, Peptides, and Proteins

Which statement about aromatic amino acids is CORRECT?

When the ribosome forms a peptide bond, which two atoms form a covalent bond?

How can a polypeptide have only one free amino group and one free carboxyl group?

A protein with a high percentage of lysine and arginine residues would be BEST purified and concentrated with which type of column?

Titration of valine by a strong base, for example NaOH, reveals two pK's. The titration reaction occurring at pK2 (pK2 = 9.62) is:

Two amino acids of the standard 20 contain sulfur atoms. They are:

Lys residues make up 10.5% of the weight of ribonuclease. The ribonuclease molecule contains 10 Lys residues. Calculate the molecular weight of ribonuclease.

On the molecule below, the arrow is pointing to the _____ carbon.

A protein with a high percentage of aspartate and glutamate residues would be BEST purified and concentrated with which type of column?

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.

R. Bruce Merrifield provided an innovation to synthesize peptides. Which statement does NOT describe part of his technology?

At pH 7.0, converting a proline to hydroxyproline, will have what effect on the overall charge of the protein containing it?

The Foundations of Biochemistry

Water

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Bioenergetics and Biochemical Reaction Types

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

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Titration of valine by a strong base, for example NaOH, reveals two pK's. The titration reaction occurring at pK₂ (pK₂ = 9.62) is:

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.