Amino Acids

Question 1

what are the building blocks of proteins called? Describe the structure.

Answer 1

Amino acids (tetrahedral structure, alpha carbon bounded to amino, carboxy group, H, and R group (side chain).

Question 2

What are the functions of amino acids?

Answer 2

signal molecules (like neurotransmitters), precursors to other biomolecules (like hormones, nucleic acids, lipids)

Question 3

List 2 ways of visualizing biomolecules

Answer 3

Fisher Projection used to view constituent atoms (H and and C) with horizontal and vertical lines. and stereochemical rendering to view shape (solid wedge- bond toward viewer; dash- bond away from viewer)

Question 4

What is an R group?

Answer 4

Side chain or structure that provides amino acid with it’s own identity.

Question 5

What is term to describe molecule with alpha carbon bonded to 4 different groups? provide examples.

Answer 5

Chiral (2 mirror-image forms) like L isomer and D isomer. only L isomers are found in proteins.

Question 6

What is the important property of amino and carboxy groups in amino acids

Answer 6

They are ionizable (able to pick up or release protons), and change charge.

Question 7

what alters ionization state of amino acids?

Answer 7

changes in pH

Question 8

What is a zwitterion (dipolar ion)?

Answer 8

An ion carrying a negative and positive charge (net charge= 0)

Question 9

Describe the structure of an amino acid in its dipolar form.

Answer 9

amino group protonated (NH3+) and carboxyl group is deprotonated (COO-)

Question 10

what happens to structure of amino acid when pH is low (pH of 1)? pH increases a little (around 3-7)

Answer 10

pH low- carboxyl group (COOH) not dissociated, and amino group protonated (NH3+)
pH increases- carboxyl group gives up its H. (COO-) and amino still protonated.

Question 11

At what pH does an amino group lose a proton (NH2)

Answer 11

pH of 9

Question 12

List the 4 classification of amino acids.

Answer 12

Hydrophobic amino acids (nonpolar R group), polar (r group neutral charge), negatively charged amino acids, and positively charge amino acids

Question 13

how many amino acids are found in proteins? Describe how their side chains vary.

Answer 13

20 amino acids. side chains vary by size, shape, charge and h-bonding capacity, hydrophobic character, chemical reactivity.

Question 14

List the amino acids that are hydrophobic? Polar? Negatively charged? positively charged?

Answer 14

Hydrophobic- Glycine, alanine, Methionine, valine, leucine, isoleucine, proline.
Polar- serine, threorine, tyrosine, cysteine, asparigine, glutamine
postively charged- lysine, arginine, and histidine
negatively charged- Aspartate and glutamate.

Question 15

Describe the hydrophobic effect? Why is it important

Answer 15

Hydrophobic effect- describes the tendency of hydrophobic molecules to cluster together in an attempt to get away from aqueous environment. hydrophobic effect is driving force for forming unique 3d architecture of proteins .

Question 16

What amino acid has a guanidinium group?

Answer 16

Arginine

Question 17

which amino acids have ionizable side chains?

Answer 17

Cysteine, tyrosine, arginine, lysine, histidine, aspartic and glutamic acid. Ionizable - can make ionic bonds, accept or donate protons.

Question 18

What are essential amino acids? List them.

Answer 18

The amino acids that humans cannot make themselves and must be applied through diet. The essential amino acids are histidine, isoleucine, leucine, valine, methionine, phenylalanine, threonine and tryptophan, lysine, arginine

Question 19

Kwashiorkor is a condition of malnutrition. How does this condition manifest itself? What is the
cure

Answer 19

j

Question 20

What are the four groups of amino acids? How are these groups defined?

Answer 20

f

Question 21

What is the ionization state of an amino acid? What does pH have to do with this state?

Answer 21

Ionization state of aa- in acidic environment, pH is low, amino group is protonated NH3+ and carboxylic group is normal (COOH). When the pH is raised, COOH is the first to give up its proton, deprotonate and from COO-, meanwhile, NH3 will deprotonate and form NH2.

Question 22

Understand the general structure of an amino acid. What is the alpha (α) carbon? Which isomer
is used in the synthesis of proteins?

Answer 22

n