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 -2

B +2

C 0

D +1

Question #2

The charge of cysteine at pH below 2 is

A 0

B -1

C +1

D -2

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 +3

C +2

D -1

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 Tyrosine

B Glutamic acid

C Histidine

D Leucine

E Cysteine

Question #8

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

A Glutamic Acid

B Lysine

C Asparagine

D Histidine

Question #9

The fully protonated form of histidine has a ____________charge.

A +1

B +4

C +3

D +2

Question #10

Chose the best true statement

A Proteases are involved in anabolism

B Proteases can cleave at specific points in the peptide chain

C Two of the statement are incorrect

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 Cleave peptide bonds

B three of the choices are correct

C Degrade proteins

D cleaves disulfide bonds

E Produce amino acids or short peptides

Question #12

A protease

A is also called a peptidase or proteinase

B All the above statements are correct

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

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

E increases the rate of proteolysis

Question #13

Which of the following is an amino acid?

A Alanine

B Proline

C Glycine

D Serine

Question #14

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

A glycine; is unbranched

B lysine; contains only nitrogen

C alanine; is a simple methyl group

D proline; forms a covalent bond with the amino group

E glycine; is a hydrogen atom

Question #15

How many different standard amino acids are there?

A 20

B 100

C 3

D an infinite number

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 Leucine & Glycine

D Asparagine & Glutamine

Question #17

An essential amino acid is one that

A the body can synthesize under essential conditions

B the body cannot synthesize

C is essential to flagella motion

D is essentially easy to synthesize

Question #18

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

A Glycine

B Methionine

C Leucine

D Phenylalanine

E Arginine

Question #19

A prosthetic group is:

A synonymous with “protomer”

B a nonidentical subunit of a protein with many identical subunits

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

D a subunit of an oligomeric protein

E a fibrous region of a globular protein

Question #20

At the isoelectric pH of a tetrapeptide:

A only the amino and carboxyl termini contribute charge

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

C the amino and carboxyl termini are not charged

D the total net charge is zero

E there are four ionic charges

Question #21

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

A isomerization

B cleavage

C oxidation reduction

D group transfer

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 positive charge

B no net charge

C no charged groups

D a net negative charge

E positive and negative charges in equal concentration

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 —COOH + —NH2 → —COO– + —NH2+

B —NH3+ + OH– → —NH2 + H2O

C —COO– + —NH2+ → —COOH + —NH2

D —COOH + OH– → —COO– + H2O

E —NH2 + OH– → —NH– + H2O

Question #24

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

A neutral molecule or an ion

B acid or a base

C standard or a nonstandard monomer in proteins

D transparent or a light-absorbing compound

E polar or a nonpolar molecule

Question #25

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

A is symmetric

B is bonded to four different chemical groups

C has no net charge

D is a carboxylic acid

E is in the L absolute configuration in naturally occurring proteins

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