Question 1

Explain what is meant by motifs in protein structure.

Accepted Answer

Motifs are particularly stable

Question 2

The structural classification of proteins (based on motifs)is based primarily on their:

Accepted Answer

A) amino-acid sequence. 
B) evolutionary relationships. 
C) function. 
D) secondary structure content and arrangement. 
E) subunit content and arrangement. 
A) amino-acid sequence. 
B) evolutionary relationships. 
C) function. 
D) secondary structure content and arrangement. 
E) subunit content and arrangement.

Question 3

Draw the resonance structure of a peptide bond,and explain why there is no rotation around the C-N bond.

Accepted Answer

The intermediate resonance str

Question 4

Explain how circular dichroism spectroscopy could be used to measure the denaturation of a protein.

Accepted Answer

Circular dichroism spectroscopy measures

Question 5

A repeating structural unit in a multimeric protein is known as a(n):

Accepted Answer

A) domain. 
B) motif. 
C) oligomer. 
D) protomer. 
E) subunit. 
A) domain. 
B) motif. 
C) oligomer. 
D) protomer. 
E) subunit.

Question 6

Describe the quaternary structure of hemoglobin.

Accepted Answer

Each protein molecule is compo

Question 7

Protein S will fold into its native conformation only when protein Q is also present in the solution.However,protein Q can fold into its native conformation without protein S.Protein Q,therefore,may function as a ____________ for protein S.

Accepted Answer

A) proteasome 
B) molecular chaperone 
C) protein precursor 
D) structural motif 
E) supersecondary structural unit 
A) proteasome 
B) molecular chaperone 
C) protein precursor 
D) structural motif 
E) supersecondary structural unit

Question 8

Which of the following is not known to be involved in the process of assisted folding of proteins?

Accepted Answer

A) Chaperonins 
B) Disulfide interchange 
C) Heat shock proteins 
D) Peptide bond condensation 
E) Peptide bond isomerization 
A) Chaperonins 
B) Disulfide interchange 
C) Heat shock proteins 
D) Peptide bond condensation 
E) Peptide bond isomerization

Question 9

In an $\alpha$ helix,the R groups on the amino acid residues:

Accepted Answer

A) alternate between the outside and the inside of the helix. 
B) are found on the outside of the helix spiral. 
C) cause only right-handed helices to form. 
D) generate the hydrogen bonds that form the helix. 
E) stack within the interior of the helix. 
A) alternate between the outside and the inside of the helix. 
B) are found on the outside of the helix spiral. 
C) cause only right-handed helices to form. 
D) generate the hydrogen bonds that form the helix. 
E) stack within the interior of the helix.

Question 10

Which of the following pairs of bonds within a peptide backbone show free rotation around both bonds?

Accepted Answer

A) C $\alpha$ -C and N-C $\alpha$ 
B) C=O and N-C 
C) C=O and N-C $\alpha$ 
D) N-C and C $\alpha$ -C 
E) N-C $\alpha$  and N-C 
A) C $\alpha$ -C and N-C $\alpha$ 
B) C=O and N-C 
C) C=O and N-C $\alpha$ 
D) N-C and C $\alpha$ -C 
E) N-C $\alpha$  and N-C

Question 11

Which of the following statements is false?

Accepted Answer

A) Collagen is a protein in which the polypeptides are mainly in the $\alpha$-helix conformation. 
B) Disulfide linkages are important for keratin structure. 
C) Gly residues are particularly abundant in collagen. 
D) Silk fibroin is a protein in which the polypeptide is almost entirely in the $\beta$ conformation. 
E) ($\alpha$-keratin is a protein in which the polypeptides are mainly in the $\alpha$0-helix conformation.) 
A) Collagen is a protein in which the polypeptides are mainly in the $\alpha$-helix conformation. 
B) Disulfide linkages are important for keratin structure. 
C) Gly residues are particularly abundant in collagen. 
D) Silk fibroin is a protein in which the polypeptide is almost entirely in the $\beta$ conformation. 
E) ($\alpha$-keratin is a protein in which the polypeptides are mainly in the $\alpha$0-helix conformation.)

Question 12

Roughly how many amino acids are there in one turn of an $\alpha$helix?

Accepted Answer

A) 1 
B) 2)8 
C) 3)6 
D) 4)2 
E) 10 
A) 1 
B) 2)8 
C) 3)6 
D) 4)2 
E) 10

Question 13

Name four factors (bonds or other forces)that contribute to stabilizing the native structure of a protein,and describe one condition or reagent that interferes with each type of stabilizing force.

Accepted Answer

Any of the following forces stabilize na

Question 14

The three-dimensional conformation of a protein may be strongly influenced by amino acid residues that are very far apart in sequence.This relationship is in contrast to secondary structure,where the amino acid residues are:

Accepted Answer

A) always side by side. 
B) generally near each other in sequence. 
C) invariably restricted to about 7 of the 20 standard amino acids. 
D) often on different polypeptide strands. 
E) usually near the polypeptide chain's amino terminus or carboxyl terminus. 
A) always side by side. 
B) generally near each other in sequence. 
C) invariably restricted to about 7 of the 20 standard amino acids. 
D) often on different polypeptide strands. 
E) usually near the polypeptide chain's amino terminus or carboxyl terminus.

Question 15

Why are glycine and proline often found within a $\beta$ turn?

Accepted Answer

A @#LAT-DLM& turn results in a tight 180° reversal

Question 16

Provide a brief explanation for the statement "Soluble globular proteins can be distinguished from soluble intrinsically disordered proteins on the basis of their amino acid content."

Accepted Answer

Soluble globular proteins contain signif

Question 17

Proteostasis is the cellular process by which:

Accepted Answer

A) proteins are synthesized. 
B) proteins are folded. 
C) proteins are modified. 
D) proteins are degraded. 
E) protein levels are maintained. 
A) proteins are synthesized. 
B) proteins are folded. 
C) proteins are modified. 
D) proteins are degraded. 
E) protein levels are maintained.

Question 18

Proteins are classified within families or superfamilies based on similarities in:

Accepted Answer

A) evolutionary origin. 
B) physico-chemical properties. 
C) structure and/or function. 
D) subcellular location. 
E) subunit structure. 
A) evolutionary origin. 
B) physico-chemical properties. 
C) structure and/or function. 
D) subcellular location. 
E) subunit structure.

Question 19

In the diagram below,the plane drawn behind the peptide bond indicates the:

Accepted Answer

A) absence of rotation around the C-N bond because of its partial double-bond character. 
B) plane of rotation around the C $\alpha$ -N bond. 
C) region of steric hindrance determined by the large C=O group. 
D) region of the peptide bond that contributes to a Ramachandran plot. 
E) theoretical space between -180 and +180 degrees that can be occupied by the $\phi$ and $\Psi$ angles in the peptide bond. 
A) absence of rotation around the C-N bond because of its partial double-bond character. 
B) plane of rotation around the C $\alpha$ -N bond. 
C) region of steric hindrance determined by the large C=O group. 
D) region of the peptide bond that contributes to a Ramachandran plot. 
E) theoretical space between -180 and +180 degrees that can be occupied by the $\phi$ and $\Psi$ angles in the peptide bond.

Question 20

All of the following are considered "weak" interactions in proteins except:

Accepted Answer

A) hydrogen bonds. 
B) hydrophobic interactions. 
C) ionic bonds. 
D) peptide bonds. 
E) van der Waals forces. 
A) hydrogen bonds. 
B) hydrophobic interactions. 
C) ionic bonds. 
D) peptide bonds. 
E) van der Waals forces.

Exam 4: The Three-Dimensional Structure of Proteins

Explain what is meant by motifs in protein structure.

The structural classification of proteins (based on motifs)is based primarily on their:

Draw the resonance structure of a peptide bond,and explain why there is no rotation around the C-N bond.

Explain how circular dichroism spectroscopy could be used to measure the denaturation of a protein.

A repeating structural unit in a multimeric protein is known as a(n):

Describe the quaternary structure of hemoglobin.

Protein S will fold into its native conformation only when protein Q is also present in the solution.However,protein Q can fold into its native conformation without protein S.Protein Q,therefore,may function as a ____________ for protein S.

Which of the following is not known to be involved in the process of assisted folding of proteins?

In an α\alphaα helix,the R groups on the amino acid residues:

Which of the following pairs of bonds within a peptide backbone show free rotation around both bonds?

Which of the following statements is false?

Roughly how many amino acids are there in one turn of an α\alphaα helix?

Name four factors (bonds or other forces)that contribute to stabilizing the native structure of a protein,and describe one condition or reagent that interferes with each type of stabilizing force.

The three-dimensional conformation of a protein may be strongly influenced by amino acid residues that are very far apart in sequence.This relationship is in contrast to secondary structure,where the amino acid residues are:

Why are glycine and proline often found within a β\betaβ turn?

Provide a brief explanation for the statement "Soluble globular proteins can be distinguished from soluble intrinsically disordered proteins on the basis of their amino acid content."

Proteostasis is the cellular process by which:

Proteins are classified within families or superfamilies based on similarities in:

In the diagram below,the plane drawn behind the peptide bond indicates the:

All of the following are considered "weak" interactions in proteins except:

The Foundations of Biochemistry

Water

Amino Acids, peptides, and 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

In an $\alpha$ helix,the R groups on the amino acid residues:

Roughly how many amino acids are there in one turn of an $\alpha$ helix?

Why are glycine and proline often found within a $\beta$ turn?