Question 1

Describe some of the features of an α helix.

Accepted Answer

The α helix is a coil stabilized by intrachain hydrogen bonds between the carbonyl oxygen of a residue and the amide hydrogen of the fourth residue away. There are 3.6 amino acids per turn. The hydrogen bonds are between amino acid residues that have three intervening residues. Thus, these amino acid residues are found on the same side of the coil. The helix is almost always right-handed, although left-handed helices are, in theory, possible.

Question 2

What do the amino acids Tyr, Asn, and Thr have in common?

Accepted Answer

A)  aromatic rings 
B)  negatively charged at pH 7.0 
C)  positively charged at pH 7.0 
D)  double bonds in side chains 
E)  polar 
A)  aromatic rings 
B)  negatively charged at pH 7.0 
C)  positively charged at pH 7.0 
D)  double bonds in side chains 
E)  polar E

Question 3

What are some of the modifications that proteins acquire?

Accepted Answer

A)  cleavage and trimming of the protein 
B)  addition of carbohydrate groups 
C)  phosphorylation of certain groups 
D)  All of these are modifications proteins acquire. 
E)  addition of carbohydrate groups and phosphorylation of certain groups 
A)  cleavage and trimming of the protein 
B)  addition of carbohydrate groups 
C)  phosphorylation of certain groups 
D)  All of these are modifications proteins acquire. 
E)  addition of carbohydrate groups and phosphorylation of certain groups D

Question 4

What is the charged group(s) present in glycine at a pH of 7?

Accepted Answer

A)  -NH3+ 
B)  -COO- 
C)  -NH2+ 
D)  -NH3+ and -COO- 
E)  All the charged groups are present. 
A)  -NH3+ 
B)  -COO- 
C)  -NH2+ 
D)  -NH3+ and -COO- 
E)  All the charged groups are present.

Question 5

In the ribonuclease experiments performed by Anfinsen, what was the significance of the presence of the reducing agent β-mercaptoethanol?

Accepted Answer

The reducing agent reduced inc

Question 6

What does the modification involving the attachment of acetyl groups to the amino termini of proteins do?

Accepted Answer

The acetylation of the amino t

Question 7

Which two amino acids contain a sulfur atom?

Accepted Answer

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

Question 8

How does a protein's amino acid sequence influence the tertiary structure?

Accepted Answer

A protein will spontaneously f

Question 9

Which amino acid side chains are capable of ionization?

Accepted Answer

The amino acids are

Question 10

In the following peptide, which amino acid is the N-terminus? 
Phe-Ala-Gly-Arg

Accepted Answer

A)  Phe 
B)  Ala 
C)  Gly 
D)  Arg 
E)  Phe and Arg 
A)  Phe 
B)  Ala 
C)  Gly 
D)  Arg 
E)  Phe and Arg

Question 11

What is the "hydrophobic effect" as it relates to protein structure?

Accepted Answer

The three-dimensional structur

Question 12

Which of the following is most often found in proteins?

Accepted Answer

A)  D-amino acids 
B)  L-amino acids 
C)  an equal amount of D- and L-amino acids 
D)  amino acids with the $\alpha$-carbon exclusively having an R absolute configuration 
E)  amino acids with the $\alpha$-carbon exclusively having an S absolute configuration 
A)  D-amino acids 
B)  L-amino acids 
C)  an equal amount of D- and L-amino acids 
D)  amino acids with the $\alpha$-carbon exclusively having an R absolute configuration 
E)  amino acids with the $\alpha$-carbon exclusively having an S absolute configuration

Question 13

A protein is considered to be __________________ when it is converted into a randomly coiled structure without its normal activity.

Accepted Answer

The answer of A protein is considered to be __________________...

Question 14

What are prions?

Accepted Answer

Prions are proteins that can a

Question 15

Which of the following amino acids has an ionizable R-group with a pKa near neutral pH?

Accepted Answer

A)  histidine 
B)  serine 
C)  aspartic acid 
D)  lysine 
E)  tyrosine 
A)  histidine 
B)  serine 
C)  aspartic acid 
D)  lysine 
E)  tyrosine

Question 16

What is the approximate mass of a protein containing 200 amino acids? (Assume there are no other protein modifications.)

Accepted Answer

A)  2,000 
B)  11,000 
C)  22,000 
D)  222,000 
E)  None of the answers is correct. 
A)  2,000 
B)  11,000 
C)  22,000 
D)  222,000 
E)  None of the answers is correct.

Question 17

_______________ is a fibrous protein and is the primary component of wool and hair.

Accepted Answer

The answer of _______________ is a fibrous protein and is...

Question 18

Key properties of proteins include

Accepted Answer

A)  a wide range of functional groups. 
B)  an ability to possess either rigid or flexible structures as dictated by functional requirements. 
C)  the ability to interact with other proteins. 
D)  All of the answers are correct. 
E)  a wide range of functional groups and an ability to possess either rigid or flexible structures as dictated by functional requirements. 
A)  a wide range of functional groups. 
B)  an ability to possess either rigid or flexible structures as dictated by functional requirements. 
C)  the ability to interact with other proteins. 
D)  All of the answers are correct. 
E)  a wide range of functional groups and an ability to possess either rigid or flexible structures as dictated by functional requirements.

Question 19

What is the advantage of having 20 different amino acids available to form proteins?

Accepted Answer

The amino acids provide a rich diversity

Question 20

What is the advantage of protein interaction and assembly with other proteins?

Accepted Answer

When proteins interact or assemble, new

Exam 2: Protein Composition and Structure

Describe some of the features of an α helix.

What do the amino acids Tyr, Asn, and Thr have in common?

What are some of the modifications that proteins acquire?

What is the charged group(s) present in glycine at a pH of 7?

In the ribonuclease experiments performed by Anfinsen, what was the significance of the presence of the reducing agent β-mercaptoethanol?

What does the modification involving the attachment of acetyl groups to the amino termini of proteins do?

Which two amino acids contain a sulfur atom?

How does a protein's amino acid sequence influence the tertiary structure?

Which amino acid side chains are capable of ionization?

In the following peptide, which amino acid is the N-terminus? Phe-Ala-Gly-Arg

What is the "hydrophobic effect" as it relates to protein structure?

Which of the following is most often found in proteins?

A protein is considered to be __________________ when it is converted into a randomly coiled structure without its normal activity.

What are prions?

Which of the following amino acids has an ionizable R-group with a pKa near neutral pH?

What is the approximate mass of a protein containing 200 amino acids? (Assume there are no other protein modifications.)

_______________ is a fibrous protein and is the primary component of wool and hair.

Key properties of proteins include

What is the advantage of having 20 different amino acids available to form proteins?

What is the advantage of protein interaction and assembly with other proteins?

Biochemistry: an Evolving Science

Exploring Proteins and Proteomes

DNA, RNA, and the Flow of Genetic Information

Exploring Genes and Genomes

Exploring Evolution and Bioinformatics

Hemoglobin: a Portrait of a Protein in Action

Enzymes: Basic Concepts and Kinetics

Oxidative Phosphorylation

Catalytic Strategies

Regulatory Strategies

Carbohydrates

Lipids and Cell Membranes

Membrane Channels and Pumps

Signal-Transduction Pathways

Metabolism: Basic Concepts and Design

Glycolysis and Gluconeogenesis

The Citric Acid Cycle

The Light Reactions of Photosynthesis

The Calvin Cycle and the Pentose Phosphate Pathway

Glycogen Metabolism

Fatty Acid Metabolism

Protein Turnover and Amino Acid Catabolism

The Biosynthesis of Amino Acids

Nucleotide Biosynthesis

Biosynthesis of Membrane Lipids and Steroids

The Integration of Metabolism

DNA Replication, Repair, and Recombination

Rna Synthesis and Processing

Protein Synthesis

The Control of Gene Expression in Prokaryotes

The Control of Gene Expression in Eukaryotes

Sensory Systems

The Immune System

Molecular Motors

Drug Development

Filters

Which of the following amino acids has an ionizable R-group with a pK_a near neutral pH?