Classification

Question 1

AAs with uncharged polar side chains

Answer 1

1. Serine
2. Threonine
3. Tyrosine
4. Asparagine
5. Glutamine
6. Cysteine

Question 2

AAs with acidic side chains

Answer 2

1. Aspartic Acid

2. Glutamic Acid

Question 3

AAs with basic side chains

Answer 3

1. Histidine
2. Lysine
3. Arginine

Question 4

AAs with nonpolar side chains

Answer 4

1. Glycine
2. Alanine
3. Valine
4. Leucine
5. Isoleucine
6. Phenylalanine
7. Tryptophan
8. Methionine
9. Proline

Question 5

Properties of nonpolar side chains

Answer 5

• do not gain or lose protons or participate in H or ionic bonds
• oily, promoting hydrophobic interactions
• in aqueous solutions: cluster together in interior of protein (hydrophobic effect)
• in hydrophobic environments (i.e. a membrane): found on outside surface of protein interacting with lipid environment

ex: Sickle Cell is result of substitution of polar Glu by nonpolar Val

Question 6

Properties of uncharged polar side chains

Answer 6

• zero net charge at neutral pH
• Ser, Thr, and Tyr each have a polar OH group that can participate in H bonding
• Asp and Glu each have a carbonyl group and amide group that can participate in H bonding

Question 7

Properties of acidic side chains

Answer 7

• proton donors

- side chains are fully ionized at physiologic pH, containing a COO-

Question 8

Properties of basic side chains

Answer 8

• Lys and Arg side chains are fully ionized at physiologic pH and positively charged
• His is weakly basic and largely uncharged at pH 7 but can be pos or neg charged when incorporated into a protein

Question 9

AAs found in interior of proteins

Answer 9

Leucine
Isoleucine
Alanine
Valine
Methionine