Question 1

Given the following pK's what is the principal form of serine at pH 5?
PKa1 = 2.21 pKa2 = 9.15 pKR  = 13

Accepted Answer

A)   a1 = 2.21 pKa2 = 9.15 pKR  = 13 
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G) B) and C)

Question 2

Arginine has the following pKa values
pK1 = 2.17 , pK2 = 9.04 pKR = 12.48
Give the net charge at the following pH's 1, 2, 4, 7, 10

Accepted Answer

pH = 1, charge = +1 ...

Question 3

The major component of the dry weight of cells is _______.

Accepted Answer

A)   Carbohydrate
B)   Protein
C)   Fats
D)   Minerals
E)   The major component will vary from organism to organismF) D) and E)
G) B) and D)

Question 4

The identity and arrangement of amino acids on the surface of a globular protein are important because they may:

Accepted Answer

A)   Interact to form specific binding cavities
B)   Stabilize the tertiary structure of the protein
C)   Bind regulatory molecules
D)   Both A and C are correct
E)   All of the above are correctF) All of the above
G) None of the above

Question 5

Consider the following tripeptide
Gly-Ala-Val
Glycine pKS1U1B11S1U1B0 = 2.34 pKS1U1B12S1U1B0 = 9.60 Alanine pKS1U1B11S1U1B0 = 2.34 pKS1U1B12S1U1B0 = 9.69
Valine pKS1U1B11S1U1B0 = 2.32 pKS1U1B12S1U1B0 = 9.62
-What is its approximate isoelectric point of this molecule?

Accepted Answer

The pI is calculated by taking the average of the pK₂ of glycine and the pk₁ of Valine (2.32 + 9.60)/2 = 5.97

Question 6

What is a Schiff base? Give an example of a reaction involving a Schiff base.

Accepted Answer

A Schiff base is the imine product of the reaction between amine and carbonyl groups. Schiff bases are intermediates that form during a transamination reaction.
  A Schiff Base

Question 7

Invariant amino acids in a protein are presumed:

Accepted Answer

A)   To be unimportant in the structure and function of the protein
B)   To be essential to the structure and function of the protein
C)   Always to occur at the beginning of the amino acid sequence of an enzyme
D)   Always to occur at the end of the amino acid sequence of an enzyme
E)   To be part of the prosthetic groupF) C) and D)
G) All of the above

Question 8

Proteins containing L-amino acids form right-handed helices, whereas proteins containing D-amino acids form left-handed helices. Would a racemic mixture (equal amounts of D and L-amino acids) form a helix?

Accepted Answer

In order to form a helix, a pr...

Question 9

A polypeptide has a high pI value. Which of the following amino acids are likely to be present?

Accepted Answer

A)   Glycine
B)   Serine
C)   Valine
D)   Aspartic acid
E)   ArginineF) B) and C)
G) All of the above

Question 10

The initial estimate for protein coding genes in humans was 100,000 instead of the approximately 20,000 genes that have been confirmed. What factors explain this discrepancy?

Accepted Answer

Several protein products (proteoforms) c...

Question 11

Which of the following amino acids would be classified as a nonstandard amino acid?

Accepted Answer

A)   Tyrosine
B)   Lysine
C)   Cystine
D)   Glycine
E)   ArginineF) A) and C)
G) All of the above

Question 12

The total number of proteins that can be produced from any 10 amino acids is?

Accepted Answer

A)   1020
B)   2010
C)   100
D)   200
E)   1010F) A) and B)
G) A) and C)

Question 13

Detergents denature proteins by disrupting which of the following?

Accepted Answer

A)   Hydrogen bonds
B)   Disulfide bridges
C)   Hydrophobic interactions
D)   Salt bridges
E)   Both A and B are correctF) B) and E)
G) None of the above

Question 14

Which of the following statements is true of the Bohr effect?

Accepted Answer

A)   Oxygen is delivered to cells in proportion to their needs
B)   Binding of protons to hemoglobin molecules facilitates the binding of oxygen
C)   Metabolic waste products bond to oxyhemoglobin
D)   A and B are both true
E)   All of the above are trueF) B) and E)
G) B) and C) A

Question 15

-pleated sheets are associated with what level of protein structure?

Accepted Answer

A)   Primary
B)   Secondary
C)   Tertiary
D)   Quaternary
E)   SuperquaternaryF) C) and D)
G) B) and E)

Question 16

Which amino acid is the precursor of the following molecule called serotonin?

Accepted Answer

Serotonin ...

Question 17

Phosphoserine is a modified amino acid. How many inflection points would there be in a titration of this molecule?
  Phosphoserine

Accepted Answer

There would be an inflection p...

Question 18

What is a zwitterion?

Accepted Answer

A zwitterion is a mo...

Question 19

Is it possible for a multifunctional protein to improve its activity for one function without affecting the activity of another function?

Accepted Answer

Improvement of one function may not affe...

Question 20

Consider the following dipeptide. Which letter indicates an amide bond?

Accepted Answer

A)   A
B)   B
C)   C
D)   D
E)   EF) B) and D)
G) None of the above

Exam 5: Amino Acids, Peptides, and Proteins

Given the following pK's what is the principal form of serine at pH 5? PKa1 = 2.21 pKa2 = 9.15 pKR = 13

Correct AnswerverifiedShow Answer

Arginine has the following pKa values pK1 = 2.17 , pK2 = 9.04 pKR = 12.48 Give the net charge at the following pH's 1, 2, 4, 7, 10

Correct AnswerverifiedpH = 1, charge = +1 ...View AnswerShow Answer

The major component of the dry weight of cells is _______.

Correct AnswerverifiedShow Answer

The identity and arrangement of amino acids on the surface of a globular protein are important because they may:

Correct AnswerverifiedShow Answer

Consider the following tripeptide Gly-Ala-Val Glycine pK1 = 2.34 pK2 = 9.60 Alanine pK1 = 2.34 pK2 = 9.69 Valine pK1 = 2.32 pK2 = 9.62 -What is its approximate isoelectric point of this molecule?

Correct AnswerverifiedThe pI is calculated by taking the average of the pK2 of glycine and the pk1 of Valine (2.32 + 9.60)/2 = 5.97

What is a Schiff base? Give an example of a reaction involving a Schiff base.

Correct AnswerverifiedA Schiff base is the imine product of the reaction between amine and carbonyl groups. Schiff bases are intermediates that form during a transamination reaction. 11ed58ed_cbce_94d6_b814_494ce243b09d_TBO1045_00 A Schiff Base

Invariant amino acids in a protein are presumed:

Correct AnswerverifiedShow Answer

Proteins containing L-amino acids form right-handed helices, whereas proteins containing D-amino acids form left-handed helices. Would a racemic mixture (equal amounts of D and L-amino acids) form a helix?

Correct AnswerverifiedIn order to form a helix, a pr...View AnswerShow Answer

A polypeptide has a high pI value. Which of the following amino acids are likely to be present?

Correct AnswerverifiedShow Answer

The initial estimate for protein coding genes in humans was 100,000 instead of the approximately 20,000 genes that have been confirmed. What factors explain this discrepancy?

Correct AnswerverifiedSeveral protein products (proteoforms) c...View AnswerShow Answer

Which of the following amino acids would be classified as a nonstandard amino acid?

Correct AnswerverifiedShow Answer

The total number of proteins that can be produced from any 10 amino acids is?

Correct AnswerverifiedShow Answer

Detergents denature proteins by disrupting which of the following?

Correct AnswerverifiedShow Answer

Which of the following statements is true of the Bohr effect?

Correct AnswerverifiedA

-pleated sheets are associated with what level of protein structure?

Correct AnswerverifiedShow Answer

Which amino acid is the precursor of the following molecule called serotonin?

Correct AnswerverifiedSerotonin ...View AnswerShow Answer

Phosphoserine is a modified amino acid. How many inflection points would there be in a titration of this molecule? Phosphoserine

Correct AnswerverifiedThere would be an inflection p...View AnswerShow Answer

What is a zwitterion?

Correct AnswerverifiedA zwitterion is a mo...View AnswerShow Answer

Is it possible for a multifunctional protein to improve its activity for one function without affecting the activity of another function?

Correct AnswerverifiedImprovement of one function may not affe...View AnswerShow Answer

Consider the following dipeptide. Which letter indicates an amide bond?

Correct AnswerverifiedShow Answer

Given the following pK's what is the principal form of serine at pH 5? PK_a1 = 2.21 pK_a2 = 9.15 pK_R = 13

Correct Answer
verified

Arginine has the following pKa values pK₁ = 2.17 , pK₂ = 9.04 pK_R = 12.48 Give the net charge at the following pH's 1, 2, 4, 7, 10

Correct Answer
verified
pH = 1, charge = +1 ...
View Answer

Correct Answer
verified

Correct Answer
verified

Consider the following tripeptide Gly-Ala-Val Glycine pK₁ = 2.34 pK₂ = 9.60 Alanine pK₁ = 2.34 pK₂ = 9.69 Valine pK₁ = 2.32 pK₂ = 9.62 -What is its approximate isoelectric point of this molecule?

Correct Answer
verified
The pI is calculated by taking the average of the pK₂ of glycine and the pk₁ of Valine (2.32 + 9.60)/2 = 5.97

Correct Answer
verified
A Schiff base is the imine product of the reaction between amine and carbonyl groups. Schiff bases are intermediates that form during a transamination reaction. 11ed58ed_cbce_94d6_b814_494ce243b09d_TBO1045_00 A Schiff Base

Correct Answer
verified

Correct Answer
verified
In order to form a helix, a pr...
View Answer

Correct Answer
verified

Correct Answer
verified
Several protein products (proteoforms) c...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
A

Correct Answer
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Correct Answer
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Serotonin ...
View Answer

Correct Answer
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There would be an inflection p...
View Answer

Correct Answer
verified
A zwitterion is a mo...
View Answer

Correct Answer
verified
Improvement of one function may not affe...
View Answer

Correct Answer
verified