Amino Acids (Serwer 2)

Question 1

Proteins are polymers of ______.

Answer 1

Amino acids

Question 2

Common structure of amino acids

Answer 2

Question 3

Exception to the common structure of amino acids

Answer 3

Proline - an imino acid

Question 4

______ are compounds related by a mirror image (cannot superimpose).

Answer 4

Opical isomers

Question 5

Amino acids have one chiral center except for _______.

Answer 5

Glycine - the R group is a second H atom

Question 6

Electrical Charging of Amino Acids:

1. A base binds a hydrogen ion produced by dissociation of water. In water, the amino group acts as a _____ and acquries a _______ charge.

Answer 6

• Base
• Positive charge

Question 7

Electrical Charging of Amino Acids:

1. An acid releases a hydrogen ion that associates with water. In water, the carboxyl group acts as an _____ and acquries a _______ charge.

Answer 7

• Acid
• Negative

Question 8

Features that differ among the 20 common amino acids

Answer 8

Side chains

Question 9

Aliphatic (hydrophobic) amino acids

Answer 9

• Glycine (gly)
• Alanine (ala)
• Valine (val)
• Leucine (leu)
• Isoleucine (ile)

Question 10

Aromatic amino acids

Answer 10

• Phenylalanine (phe)
• Tyrosine (tyr)
• Tryptophan (trp)

Question 11

Acidic amino acids

Answer 11

• Aspartic acid (asp) (pH 4.1)
• Glutamic acid (glu) (pH 4.1)

Question 12

Basic amino acids

Answer 12

• Histidine (his) (pH 6.0)
• Lysine (lys) (pH 10.8)

Arginine (arg) (pH 12.5)

Question 13

Aliphatic hydroxyl amino acids

Answer 13

• Serine (ser)
• Threonine (thr)

Question 14

Aliphatic amide

Answer 14

• Asparagine (asn)
• Glutamine (gln)

Question 15

Sulfur-containing amino acids

Answer 15

• Cysteine (cys)
• Methionine (met)

Question 16

Imino acid

Answer 16

Proline (pro)

Question 17

Post-translational modification of amino acids: Hydroxyproline/Hydroxylysine

Answer 17

• Prolyl and lysyl hydroxylases: cofactor = Vitamin C (ascorbate)
• Need hydroxylated forms for collagen

Question 18

________ is the separation of molecules achieved by exposing them to an electrical field.

Answer 18

Electrophoresis

Question 19

_______ is electrophoresis through a medium that has both buffer and gel.

Answer 19

Gel electrophoresis

Question 20

For electrophoresis without the gel, the speed of migration is governed by the _________.

Answer 20

Average electrical charge per unit area of a particle

Question 21

In gel electrophoresis the _____ of the particle is an additional factor.

Answer 21

Size (surface area)

Question 22

The anode is ______ charged, while the cathode is _______ charged. Negatively charged ions, called ______, move toward the _______. Positively charged ions, called ______, move toward the _______.

Answer 22

• Positively
• Negatively
• Anions; anode
• Cations; cathode

Question 23

Post-translational modification of amino acids: Phosphoserine (also: phosphothreonine and phosphotyrosine - signal functions)

Answer 23

• Kinase
• Results from cellular signaling from hormones and can lead to activation of target enzymes

Question 24

Post-translational modification of amino acids: gamma-carboxyglutamic acid

Answer 24

• Carboxylase - Requires Vitamin K cofactor
• Post-translational modification of blood clotting factors (prothrombin)

Question 25

Hydrophobic amino acid residues are most often in the _____ of water soluble proteins and includes…

Answer 25

Interior

Question 26

Hydrophilic amino acid residues are most often on _____ of water soluble proteins and include…

Answer 26

The surface

Question 27

Structure breaking amino acids

Answer 27

1. Glycine - no side chain, which causes high thermal motion in the neighborhood of glycines (room to jiggle; collagen triple helix needs glycine, about 1/3)
2. Proline - Rigidly in a conformation inconsistent with either alpha helix or beta sheet (too rigid in wrong conformation)

Question 28

Difference between normal hemoglobin and sickle cell

Answer 28

Charged residue (glutamate) is replaced with a hydrophobic residue (valine)

Question 29

What does chirmal mean when referring to an amino acid?

Answer 29

Mirror image cannot be superimposed

Question 30

What is the only amino acid found in proteins that does not exist as D-, L- isomers?

Answer 30

Glycine

Question 31

Which of the following amino acid side chains ahve the same carbon skeleton?

-Ala, Gly, Thr, Leu, Trp, Cys

Answer 31

Ala, Thr, Cys

Question 32

The disease scurvy is caused by dietary deficiency of vitamin C. Why is loss of teeth a symptom of this disease?

Answer 32

Affects the collagen; ligaments holding teeth fall apart

Question 33

Which are the structure breaking amino acids?

Answer 33

Glycine and Proline

Question 34

Which form of the cysteine side-chain funcational group is depticted? Is it protonated acidic form or the unprotonated form? What would the other form look like and what would its charge be in comparison to the form shown?

Answer 34

• Protonated
• S-

Question 35

If normal hemoglobin moves to the anode (+pole) during electrophoresis, and is converted to sickle cell hemoglobin by replacement of glutamic acid with a valine, then what effect will this change in charge have on the speed of sickle cell hemoglobin during electrophoresis?

Answer 35

Move less rapidly