Lecture 6. Proteins

Question 1

What do proteins consist of ?

Answer 1

Amino acids

Question 2

Name the amino acids who are polar, with uncharged R groups

Answer 2

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

Question 3

Name the amino acids which are nonpolar and have aliphatic R groups

Answer 3

1. Glycine
2. Alanine
3. Proline
4. Valine
5. Leucine
6. Isoleucine
7. Methionine

Question 4

Which amino acid has a disulfide bond ?

Answer 4

Cysteine

Question 5

Which amino acids have negatively charged R groups.

Answer 5

1. Aspartate

2. Glutamate

Question 6

Which amino acids have aromatic R groups ?

Answer 6

1. Phenylalanine
2. Tyrosine
3. Tryptophan

Question 7

Which amino acids have positively charged R groups ?

Answer 7

1. Lysine
2. Arginine
3. Histidine

Question 8

What is the pI of a molecule ?

Answer 8

The pH at which a molecule carries no electrical charge.

Question 9

What is the Henderson - Hasselbach equation ?

Answer 9

pH = pKa + log(conc. of the conjugate base/conc. of the weak acid)

Question 10

What happens when amino acids dissolve in water ?

Answer 10

They exist as dipolar ions

Question 11

What is a dipolar ion ?

Answer 11

An ion with both a positive and negative charge

Question 12

Give two examples of dipolar ions forms.

Answer 12

1. Nonionic form

2. Zwitterionic form

Question 13

What is the isoelectric point of pepsin ?

Answer 13

Less than 1

Question 14

What is the isoelectric point of egg albumin ?

Answer 14

4.6

Question 15

What is the isoelectric point of serum albumin ?

Answer 15

4.9

Question 16

What is the isoelectric point of urease ?

Answer 16

5

Question 17

What is the isoelectric point of B-lactoglobulin ?

Answer 17

5.2

Question 18

What is the isoelectric point of hemoglobin ?

Answer 18

6.8

Question 19

What is the isoelectric point of myoglobin ?

Answer 19

7

Question 20

What is the isoelectric point of chymotrypsinogen ?

Answer 20

9.5

Question 21

What is the isoelectric point of cytochrome c ?

Answer 21

10.7

Question 22

What is the isoelectric point of lysozyme ?

Answer 22

11

Question 23

What are the four types of protein structure ?

Answer 23

1. Primary structure
2. Secondary structure
3. Tertiary structure
4. Quaternary structure

Question 24

What is the primary structure of a protein made of ?

Answer 24

Amino acid residues

Question 25

What is the secondary structure of a protein composed of ?

Answer 25

Alpha helix

Question 26

What is the tertiary structure of a protein composed of ?

Answer 26

Polypeptide chains

Question 27

What is the quaternary structure of a protein composed of ?

Answer 27

Assembled subunits

Question 28

Describe the peptide bond

Answer 28

Rigid and planar

Question 29

Why is the peptide bond planar ?

Answer 29

It contains partial double bond characters, preventing rotation

Question 30

What does an an alpha helix have (4) ?

Answer 30

1. spiral structure 2. R groups on the outside 3. intramolecular hydrogen bonding 4. a uniform diameter

Question 31

What does the beta conformation do ?

Answer 31

Organises the polypeptide chains into sheets

Question 32

In a beta sheet, what do R groups of adjacent amino acids do ?

Answer 32

They protrude in an alternating pattern

Question 33

What does 2^_0 refer to

Answer 33

spatial arrangement of amino acids in the primary structure

Question 34

What does the tertiary structure refer to ?

Answer 34

Long range aspects of amino acid sequence