Amino Acids and Protein Structure

Question 1

What four groups are attached to alpha Carbon in an amino acid?

Answer 1

1. Carboxyl group
2. Amino group
3. Hydrogen
4. Variable R group

Question 2

Acidic R-groups carry what charge?

Answer 2

Negative

Question 3

Basic R-groups carry what charge?

Answer 3

Positive

Question 4

What 3 nonpolar amino acids have bulky side chains?

Answer 4

Proline (secondary amino group), Tryptophan; Phenylalanine

Question 5

Which three uncharged polar amino acids have a hydroxyl group in thier side groups

Answer 5

1. Serine
2. Threonine
3. Tyrosine

Question 6

What is the important of having an -OH group in the side chain of an amino acid?

Answer 6

1. Highly reactive
2. Binds with sugar chains of glycoproteins
3. Binds with phosphate group of phosphorylated proteins

Question 7

Name the 6 amino acids with uncharged polar side chains?

Answer 7

1. Cystiene (S in side group)
2. Serine
3. Threonine
4. Tyrosine
5. Asparagine
6. Glutamine

Question 8

Methionine contains what in its R group?

Answer 8

Sulfur

Question 9

Methionine is encoded by what start codon?

Answer 9

AUG

Question 10

What is a significance of Asparagine having a amide group (CONH2)

Answer 10

N is the attachment for sugar chains of glycoproteins

Question 11

What type of bond is formed between the sulfhydryl groups of two cystine residues?

Answer 11

Disulfide bond

Question 12

What are the two acidic amino acids and what does thier side group contain?

Answer 12

1. Asparate and Glutamate
2. side group contain -COOH groups

Question 13

List the basic amino acids

Answer 13

1. Arginine
2. Lysine
3. Histidine

Question 14

Charged amino acids can form what types of bonds and what do these bonds depend on?

Answer 14

1. Ionic bonds: Depend on both groups remaining charged; so pH changes might disrupt the bond
2. Hydrogen bonds

Question 15

Primary structure of Proteins

Answer 15

Linear sequence of amino acids; covalently linked together by peptide bonds

Question 16

Amide bond

Answer 16

1. formed between a-carboxyl group of one amino acids and a-amino group of another amino acid
2. Also known as peptide bond

Question 17

Amino acid sequences are read from…

Answer 17

N- to the C-terminal end

Question 18

Sickle cell anemia is caused by what?

Answer 18

1. The substitution of Glutamic Acid by Valine in the sixth position of a subunit of hemoglobin protein
2. At low oxygen, mutated protein polymerizes into a long rope fiber which distorts shape of RBC -> block flow of blood in narrow capillaries

Question 19

Secondary Structure of Proteins

Answer 19

1. Local folding as a result of Hydrogen bonds between backbone amino and carboxyl groups (R-Groups NOT INVOLVED)

Question 20

What are the three types of secondary structures that are commonly found?

Answer 20

1. a-helix
2. b-sheets
3. loop

Question 21

What causes Prion disease?

Answer 21

1. Diseased prion protein is misfolded due to change from a-helix into B-sheet

Question 22

Prion disease forms what in the CNS

Answer 22

Amyloid Plaques

Question 23

What is the name for Prion disease in humans? in cattle?

Answer 23

1. Humans: Creutzfeld-jacob disease
2. Cattle: Mad-cow disease

Question 24

Tertiary Structure of Proteins

Answer 24

1. Folding and packing of secondary structures so that interior of protein contains non-polar residues and exterior contains polar residues
2. Forms DOMAINS

Question 25

Domains

Answer 25

stable structural elements within a protein that have a specific function by themselves

Question 26

Monomeric protein

Answer 26

Protein that consists of a single polypeptide chain

Question 27

Quaternary Structure of Proteins

Answer 27

arrangement of multiple polypeptide subunits of a proteins held together by NONCOVALENT interactions (H-bonds; Ionic bonds; hydrophobic interactions)