L4 Amino Acids and Proteins

Navigation » List of Schools » West Los Angeles College » Chemistry » Chem 221 – Biochemistry for Science Majors » Fall 2021 » L4 Amino Acids and Proteins

Need help with your exam preparation?

Existing Quiz Clients Login here

Below are the questions for the exam with the choices of answers:

Try The Exam

Question #1

The charge of glutamic acid at pH > 10 is

A +1

B +2

C -2

D 0

Question #2

The charge of cysteine at pH below 2 is

A -2

B +1

C -1

D 0

Question #3

The lowest charge possible for glutamic acid is

A -1

B -2

Question #4

What is the charge of the dipeptide Ala-Lys a pH = 12?

A +2

B 0

C -1

D +1

Question #5

At pH = 13, the net charge on lysine is:____________

A +1

B -1

C +3

D +2

Question #6

At pH = 0, the net charge on glutamic acid is:____________

A 0

B +1

C +2

D -1

Question #7

Based on the pKa values given in the attached table (see canvas tables), in there any amino acid among the ones in the list below that could serve as a buffer at pH 8.0?

A Histidine

B Glutamic acid

C Leucine

D Cysteine

E Tyrosine

Question #8

Which of the following amino acids has a net negative charge at physiologic pH (~7.4)?

A Glutamic Acid

B Asparagine

C Histidine

D Lysine

Question #9

The fully protonated form of histidine has a ____________charge.

A +1

B +2

C +3

D +4

Question #10

Chose the best true statement

A Proteases are involved in anabolism

B Two of the statement are incorrect

C Proteases can cleave at specific points in the peptide chain

D Proteases are involved in many biological functions, including digestion of eaten proteins, and protein catabolism

E Cleave all peptide bonds

Question #11

Proteases

A Degrade proteins

B three of the choices are correct

C Produce amino acids or short peptides

D cleaves disulfide bonds

E Cleave peptide bonds

Question #12

A protease

A increases the rate of proteolysis

B cleaves proteins by the addition of a molecule of water to a peptide bond

C All the above statements are correct

D is an enzyme that catalyzes proteolysis, the breakdown of proteins into smaller polypeptides or single amino acids

E is also called a peptidase or proteinase

Question #13

Which of the following is an amino acid?

A Proline

B Serine

C Glycine

D Alanine

Question #14

Of the 20 standard amino acids, only ___________ is not optically active (nonchiral). The reason is that its side chain ___________.

A alanine; is a simple methyl group

B proline; forms a covalent bond with the amino group

C glycine; is a hydrogen atom

D glycine; is unbranched

E lysine; contains only nitrogen

Question #15

How many different standard amino acids are there?

A an infinite number

B 3

C 20

D 100

Question #16

Which of the following pairs of amino acids would carry a negative charge on their side chain at pH 8.0?

A Aspartate & Glutamate

B Histidine & Lysine

C Asparagine & Glutamine

D Leucine & Glycine

Question #17

An essential amino acid is one that

A is essentially easy to synthesize

B is essential to flagella motion

C the body cannot synthesize

D the body can synthesize under essential conditions

Question #18

Which one of the following amino acids contains an aromatic group?

A Arginine

B Glycine

C Methionine

D Phenylalanine

E Leucine

Question #19

A prosthetic group is:

A synonymous with “protomer”

B a fibrous region of a globular protein

C a part of the protein that is not composed of amino acids

D a subunit of an oligomeric protein

E a nonidentical subunit of a protein with many identical subunits

Question #20

At the isoelectric pH of a tetrapeptide:

A two internal amino acids of the tetrapeptide cannot have ionizable R groups

B the total net charge is zero

C only the amino and carboxyl termini contribute charge

D there are four ionic charges

E the amino and carboxyl termini are not charged

Question #21

The formation of a peptide bond between two amino acids is an example of a(n) ______________ reaction.

A isomerization

B oxidation reduction

C group transfer

D cleavage

E condensation

Question #22

For amino acids with neutral R groups, at any pH below the pI of the amino acid, the population of amino acids in solution will have:

A a net negative charge

B a net positive charge

C no charged groups

D positive and negative charges in equal concentration

E no net charge

Question #23

Titration of valine by a strong base, for example NaOH, reveals two pK’s. The titration reaction occurring at pK2 (pK2 = 9.62) is:

A —NH3+ + OH– → —NH2 + H2O

B —COOH + —NH2 → —COO– + —NH2+

C —NH2 + OH– → —NH– + H2O

D —COOH + OH– → —COO– + H2O

E —COO– + —NH2+ → —COOH + —NH2

Question #24

Amino acids are ampholytes because they can function as either a(n):

A polar or a nonpolar molecule

B acid or a base

C transparent or a light-absorbing compound

D standard or a nonstandard monomer in proteins

E neutral molecule or an ion

Question #25

The chirality of an amino acid results from the fact that its α carbon:

A is symmetric

B is in the L absolute configuration in naturally occurring proteins

C has no net charge

D is bonded to four different chemical groups

E is a carboxylic acid

Try The Exam

Fresh Grad Lands Job as Real Estate Agent With Help from Professional Writers

L4 Amino Acids and Proteins

Need help with your exam preparation?

Below are the questions for the exam with the choices of answers:

Christian S.

Tyra

Linda

Manush

We accept payment