Question 1

At what point does the isoelectric point or pI occur?

Accepted Answer

A)  when all of the acidic protons are neutralized with base 
B)  at pH = 7.0 
C)  at the pH when all negative charges on a zwitterion counter the positive charges 
D)  when the molecule has a single electric charge 
A)  when all of the acidic protons are neutralized with base 
B)  at pH = 7.0 
C)  at the pH when all negative charges on a zwitterion counter the positive charges 
D)  when the molecule has a single electric charge C

Question 2

Which gives rise to a favorable enthalpic (   S)driving force for protein folding?

Accepted Answer

A)  The lining up of hydrogen bonds as the protein folds. 
B)  The limiting of possible conformations as the protein folds. 
C)  The decrease in ordered water molecules as hydrophobic amino acids pack together. 
D)  The stabilization caused by favorable electrostatic interactions of amino acid side chains. 
A)  The lining up of hydrogen bonds as the protein folds. 
B)  The limiting of possible conformations as the protein folds. 
C)  The decrease in ordered water molecules as hydrophobic amino acids pack together. 
D)  The stabilization caused by favorable electrostatic interactions of amino acid side chains. C

Question 3

The dipole moment associated with a peptide bond proceeds from which amide?

Accepted Answer

A)  the C to the O atom 
B)  the C to the N atom 
C)  the O to the H atom 
D)  the H to the O atom 
A)  the C to the O atom 
B)  the C to the N atom 
C)  the O to the H atom 
D)  the H to the O atom D

Question 4

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 5

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 @#IMG-DLM&_TB6697_11 -mercaptoethanol was r

Question 6

What is the dominant secondary structure found in hair keratin?

Accepted Answer

A)    -helices 
B)  disulfide bonds 
C)    -sheets 
D)  loop structures 
A)    -helices 
B)  disulfide bonds 
C)    -sheets 
D)  loop structures

Question 7

Which interaction largely stabilizes protein secondary (2     )structures?

Accepted Answer

A)  disulfide bonds 
B)  hydrogen bonding 
C)  hydrophobic packing 
D)  metal ions 
A)  disulfide bonds 
B)  hydrogen bonding 
C)  hydrophobic packing 
D)  metal ions

Question 8

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 9

Collagen is an important structural protein in biological systems.It is formed by a repeating unit containing glycine,proline,and 4-hydroxyproline (4HyP).The synthesis of 4HyP from proline requires vitamin C.Draw the structure of 4HyP.

Accepted Answer

The answer of Collagen is an important structural protein in...

Question 10

How many possible unique triplet codons could there be in a genome?

Accepted Answer

A)  3 
B)  20 
C)  36 
D)  64 
A)  3 
B)  20 
C)  36 
D)  64

Question 11

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

Accepted Answer

The pI is halfway be

Question 12

In the Anfinsen experiment with the unfolding of RNaseA,what order could the chemical reagents be removed in order to achieve an inactive protein?

Accepted Answer

A)  Remove denaturant first and reductant second. 
B)  Simultaneously remove denaturant and reductant. 
C)  Remove reductant first, denaturant second, and then finally add back reductant. 
D)  Remove reductant first and denaturant second. 
A)  Remove denaturant first and reductant second. 
B)  Simultaneously remove denaturant and reductant. 
C)  Remove reductant first, denaturant second, and then finally add back reductant. 
D)  Remove reductant first and denaturant second.

Question 13

What specific reagents or conditions might be found on the X-axis label of the following figure?

Accepted Answer

Reagents: chaotropic agents such as urea

Question 14

Protein tertiary structures

Accepted Answer

A)  require the formation of disulfide bonds in order to achieve their native state. 
B)  are always irreversibly destroyed by the addition of denaturants, such as urea and salts, even when the denaturants are subsequently removed. 
C)  are often disrupted by the either very low pH or very high pH values as a result of alterations in the ionization states of acidic or basic amino acids. 
D)  are generally poorly defined and cannot be determined experimentally. 
A)  require the formation of disulfide bonds in order to achieve their native state. 
B)  are always irreversibly destroyed by the addition of denaturants, such as urea and salts, even when the denaturants are subsequently removed. 
C)  are often disrupted by the either very low pH or very high pH values as a result of alterations in the ionization states of acidic or basic amino acids. 
D)  are generally poorly defined and cannot be determined experimentally.

Question 15

Which represents the correct arrangement of bonding in a peptide bond?

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 16

What is a difference between parallel and antiparallel   -sheet secondary structures?

Accepted Answer

A)  Antiparallel  -sheets have a larger number of stabilizing H bonds between backbone amides than parallel  -sheets. 
B)  Parallel  -sheets require a larger loop connecting together the individual peptide strands in the sheet. 
C)  Parallel  -sheets are longer than antiparallel sheets. 
D)  Parallel  -sheets have amino acid side chains alternating up and down, whereas antiparallel side chains alternate down and up. 
A)  Antiparallel  -sheets have a larger number of stabilizing H bonds between backbone amides than parallel  -sheets. 
B)  Parallel  -sheets require a larger loop connecting together the individual peptide strands in the sheet. 
C)  Parallel  -sheets are longer than antiparallel sheets. 
D)  Parallel  -sheets have amino acid side chains alternating up and down, whereas antiparallel side chains alternate down and up.

Question 17

Which amino acid side chain from the list below is the most polar?

Accepted Answer

A)  Gln 
B)  Ala 
C)  Leu 
D)  Phe 
A)  Gln 
B)  Ala 
C)  Leu 
D)  Phe

Question 18

Which statement regarding protein secondary structures is correct?

Accepted Answer

A)    -strands allow  -helices to interact with one another. 
B)  Protein  -helices alternate with  -strands in stabilizing protein structure. 
C)  Protein  -helices are left handed, whereas  -sheets are right handed in arrangement. 
D)  Protein  -helices and  -strands differ in that  -helices are stabilized by intrahelical hydrogen bonds, whereas  -strands are stabilized by hydrogen bonds across adjacent strands. 
A)    -strands allow  -helices to interact with one another. 
B)  Protein  -helices alternate with  -strands in stabilizing protein structure. 
C)  Protein  -helices are left handed, whereas  -sheets are right handed in arrangement. 
D)  Protein  -helices and  -strands differ in that  -helices are stabilized by intrahelical hydrogen bonds, whereas  -strands are stabilized by hydrogen bonds across adjacent strands.

Question 19

Trace directly the covalently bonded backbone atoms from the N to C terminus of a dipeptide.Which atoms are found in this trace?

Accepted Answer

A)  NCCNCC 
B)  NCCONCCO 
C)  NCONCO 
D)  CNCCNC 
A)  NCCNCC 
B)  NCCONCCO 
C)  NCONCO 
D)  CNCCNC

Question 20

Use the table below to determine how many possible RNA sequences could code for the dipeptide Pro-Ala.

Accepted Answer

A)  1 
B)  16 
C)  8 
D)  64 
A)  1 
B)  16 
C)  8 
D)  64

Exam 4: Protein Structure

At what point does the isoelectric point or pI occur?

Which gives rise to a favorable enthalpic ( S)driving force for protein folding?

The dipole moment associated with a peptide bond proceeds from which amide?

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

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?

What is the dominant secondary structure found in hair keratin?

Which interaction largely stabilizes protein secondary (2 )structures?

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

Collagen is an important structural protein in biological systems.It is formed by a repeating unit containing glycine,proline,and 4-hydroxyproline (4HyP).The synthesis of 4HyP from proline requires vitamin C.Draw the structure of 4HyP.

How many possible unique triplet codons could there be in a genome?

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

In the Anfinsen experiment with the unfolding of RNaseA,what order could the chemical reagents be removed in order to achieve an inactive protein?

What specific reagents or conditions might be found on the X-axis label of the following figure?

Protein tertiary structures

Which represents the correct arrangement of bonding in a peptide bond?

What is a difference between parallel and antiparallel -sheet secondary structures?

Which amino acid side chain from the list below is the most polar?

Which statement regarding protein secondary structures is correct?

Trace directly the covalently bonded backbone atoms from the N to C terminus of a dipeptide.Which atoms are found in this trace?

Use the table below to determine how many possible RNA sequences could code for the dipeptide Pro-Ala.

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

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