Question 1

Which of the following are negatively charged amino acids at pH = 7?

Accepted Answer

A)  Glu, Asp 
B)  Gln, Asn 
C)  Thr, Tyr 
D)  Cys, Asn 
A)  Glu, Asp 
B)  Gln, Asn 
C)  Thr, Tyr 
D)  Cys, Asn

Question 2

Calculate the pI for the following dipeptide using the pKas shown.

Accepted Answer

The pI is halfway be

Question 3

Draw the structure of the amino acid glutamate showing the predominant form found at pH
7.0 (assume -NH3+ pKa 9.0; Glu pKR 4.0; -COOH pKa 2.0).

Accepted Answer

The answer of Draw the structure of the amino acid...

Question 4

What is the peptide sequence Asp-Gln-Gly-Ser, using one-letter abbreviations for the amino acids?

Accepted Answer

A)  AGYS 
B)  DNGC 
C)  DQGS 
D)  EGYS 
A)  AGYS 
B)  DNGC 
C)  DQGS 
D)  EGYS

Question 5

Which of the following statements about $\beta$-sheet structures is true?

Accepted Answer

A)  The individual strands of all $\beta$-sheet structures are connected by turns, helices, or loops. 
B)  All amino acid side chains in antiparallel and parallel $\beta$-sheet structures point to one side of the sheet. 
C)  Parallel $\beta$-sheet structures have backbone amides that directly hydrogen bond between strands, whereas antiparallel $\beta$-sheets have hydrogen bonds that are offset. 
D)  All $\beta$-sheet structures form a spiraling backbone chain. 
A)  The individual strands of all $\beta$-sheet structures are connected by turns, helices, or loops. 
B)  All amino acid side chains in antiparallel and parallel $\beta$-sheet structures point to one side of the sheet. 
C)  Parallel $\beta$-sheet structures have backbone amides that directly hydrogen bond between strands, whereas antiparallel $\beta$-sheets have hydrogen bonds that are offset. 
D)  All $\beta$-sheet structures form a spiraling backbone chain.

Question 6

The proteins collagen, silk fibroin, and hair keratin have all of the following in common, EXCEPT that they

Accepted Answer

A)  are fibrous proteins. 
B)  are composed of repeating amino acid sequences. 
C)  are composed of $\alpha$-helical structures. 
D)  play important structural roles in biology. 
A)  are fibrous proteins. 
B)  are composed of repeating amino acid sequences. 
C)  are composed of $\alpha$-helical structures. 
D)  play important structural roles in biology.

Question 7

An $\alpha$-helix has the sequence: NH3+-Ser-Glu-Gly-Asp-Trp-Gln-Leu-His-Val-Phe-Ala-Lys-Val-Glu-COO-. The carbonyl oxygen (in the peptide bond) of the histidine residue is hydrogen bonded to the amide nitrogen of

Accepted Answer

A)  Asp. 
B)  Lys. 
C)  Trp. 
D)  Ala. 
A)  Asp. 
B)  Lys. 
C)  Trp. 
D)  Ala.

Question 8

Of the three proposed models of globular protein folding, which one describes formation of an initial disordered protein interior, followed next by ordering of secondary and tertiary structures?

Accepted Answer

A)  mutant globule 
B)  hydrophobic collapse model 
C)  framework model 
D)  nucleation model 
A)  mutant globule 
B)  hydrophobic collapse model 
C)  framework model 
D)  nucleation model

Question 9

A mutation in a gene results in the least amount of damage to the resulting protein.

Accepted Answer

A)  missense 
B)  nonsense 
C)  frameshift 
D)  silent 
A)  missense 
B)  nonsense 
C)  frameshift 
D)  silent

Question 10

Consider the whole amino acid alanine at pH =7. How many atoms (including Hs) are found in the molecule?

Accepted Answer

A)  15 
B)  13 
C)  10 
D)  8 
A)  15 
B)  13 
C)  10 
D)  8

Question 11

After analyzing all the structures of proteins found in the Protein Data Bank, scientists have found that four general classes of protein structures exist, based on their secondary structure themes. Name the four classes of general protein structures.

Accepted Answer

Predominantly @#LAT-DLM&-helical, predom

Question 12

In the famous experiment where Christian Anfinsen unfolded and refolded the protein RNaseA, in what order was the denaturant and reductant removed to give an inactive protein? Why was the protein inactive?

Accepted Answer

If the @#LAT-DLM&-mercaptoethanol was removed firs

Question 13

If the isoelectric point (pI) for an amino acid is at point A, what is the charge on the amino acid at point B?

Accepted Answer

A)  "0" 
B)  "-2" 
C)  "+2 
D)  "-1" 
A)  "0" 
B)  "-2" 
C)  "+2 
D)  "-1"

Question 14

Arrange the following in order of increasing complexity: secondary structure, tertiary structure, motif, and domain.

Accepted Answer

Secondary Structure

Question 15

In a standard $\alpha$-helix, __________ H bonds and dipole moments are found per amino acid, which stabilizes the $\alpha$-helical structure.

Accepted Answer

A)  1; 1 
B)  1; 2 
C)  2; 1 
D)  2; 2 
A)  1; 1 
B)  1; 2 
C)  2; 1 
D)  2; 2

Question 16

What is the dominant secondary structure found in hair keratin?

Accepted Answer

A)  "$\alpha$-helices" 
B)  "disulfide bonds" 
C)  "$\beta$-sheets" 
D)  "loop structures" 
A)  "$\alpha$-helices" 
B)  "disulfide bonds" 
C)  "$\beta$-sheets" 
D)  "loop structures"

Question 17

To what organic reaction class does peptide bond formation belong?

Accepted Answer

A)  condensation 
B)  isomerization 
C)  oxidation 
D)  addition 
A)  condensation 
B)  isomerization 
C)  oxidation 
D)  addition

Question 18

For the alanine titration curve shown below, which best describes point A?

Accepted Answer

A)  a buffer region 
B)  isoelectric point 
C)  second equivalence point 
D)  pH = pKa 
A)  a buffer region 
B)  isoelectric point 
C)  second equivalence point 
D)  pH = pKa

Question 19

What are the three-letter and one-letter abbreviations for the amino acid tyrosine?

Accepted Answer

A)  Tyo, T 
B)  Tyr, R 
C)  Tro, Y 
D)  Tyr, Y 
A)  Tyo, T 
B)  Tyr, R 
C)  Tro, Y 
D)  Tyr, Y

Question 20

Which of the following statements is true about $\alpha$-helices?

Accepted Answer

A)  The center of the helix is an open channel. 
B)  There are about seven amino acids per helical turn. 
C)  The amide backbone dipoles line up in one direction. 
D)  The helical backbone structure is stabilized by ionic interactions. 
A)  The center of the helix is an open channel. 
B)  There are about seven amino acids per helical turn. 
C)  The amide backbone dipoles line up in one direction. 
D)  The helical backbone structure is stabilized by ionic interactions.

Exam 4: Protein Structure

Which of the following are negatively charged amino acids at pH = 7?

Calculate the pI for the following dipeptide using the pKas shown.

Draw the structure of the amino acid glutamate showing the predominant form found at pH 7.0 (assume -NH3+ pKa 9.0; Glu pKR 4.0; -COOH pKa 2.0).

What is the peptide sequence Asp-Gln-Gly-Ser, using one-letter abbreviations for the amino acids?

Which of the following statements about β\betaβ -sheet structures is true?

The proteins collagen, silk fibroin, and hair keratin have all of the following in common, EXCEPT that they

An α\alphaα -helix has the sequence: NH3+-Ser-Glu-Gly-Asp-Trp-Gln-Leu-His-Val-Phe-Ala-Lys-Val-Glu-COO-. The carbonyl oxygen (in the peptide bond) of the histidine residue is hydrogen bonded to the amide nitrogen of

Of the three proposed models of globular protein folding, which one describes formation of an initial disordered protein interior, followed next by ordering of secondary and tertiary structures?

A mutation in a gene results in the least amount of damage to the resulting protein.

Consider the whole amino acid alanine at pH =7. How many atoms (including Hs) are found in the molecule?

After analyzing all the structures of proteins found in the Protein Data Bank, scientists have found that four general classes of protein structures exist, based on their secondary structure themes. Name the four classes of general protein structures.

In the famous experiment where Christian Anfinsen unfolded and refolded the protein RNaseA, in what order was the denaturant and reductant removed to give an inactive protein? Why was the protein inactive?

If the isoelectric point (pI) for an amino acid is at point A, what is the charge on the amino acid at point B?

Arrange the following in order of increasing complexity: secondary structure, tertiary structure, motif, and domain.

In a standard α\alphaα -helix, __________ H bonds and dipole moments are found per amino acid, which stabilizes the α\alphaα -helical structure.

What is the dominant secondary structure found in hair keratin?

To what organic reaction class does peptide bond formation belong?

For the alanine titration curve shown below, which best describes point A?

What are the three-letter and one-letter abbreviations for the amino acid tyrosine?

Which of the following statements is true about α\alphaα -helices?

Principles of Biochemistry

Physical Biochemistry: Energy Conversion, Water, and Membranes

Nucleic Acid Structure and Function

Methods in Protein Biochemistry

Protein Function

Enzyme Mechanisms

Cell Signaling Systems

Glycolysis: a Paradigm of Metabolic Regulation

The Citrate Cycle

Oxidative Phosphorylation

Photosynthesis

Carbohydrate Structure and Function

Carbohydrate Metabolism

Lipid Structure and Function

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Metabolic Integration

DNA Replication, Repair, and Recombination

RNA Synthesis, Processing, and Gene Silencing

Protein Synthesis, Posttranslational Modification, and Transport

Gene Regulation

Filters

Draw the structure of the amino acid glutamate showing the predominant form found at pH 7.0 (assume -NH₃⁺pKa 9.0; Glu pK_R 4.0; -COOH pKa 2.0).

Which of the following statements about $\beta$ -sheet structures is true?

An $\alpha$ -helix has the sequence: NH₃⁺-Ser-Glu-Gly-Asp-Trp-Gln-Leu-His-Val-Phe-Ala-Lys-Val-Glu-COO-. The carbonyl oxygen (in the peptide bond) of the histidine residue is hydrogen bonded to the amide nitrogen of

In a standard $\alpha$ -helix, __________ H bonds and dipole moments are found per amino acid, which stabilizes the $\alpha$ -helical structure.

Which of the following statements is true about $\alpha$ -helices?