Amino Acids and Proteins

Question 1

Name the biological roles of proteins?

Answer 1

1. Transport
2. Storage
3. Enzyme catalysis
4. Motion
5. Skeletal support
6. Immune protection
7. Nerve impulse transmission
8. Control of metabolism, grown and differentiation

Question 2

How many polypeptide chains do proteins consist of?

Answer 2

Can consist of a single chain or several interacting chains

Question 3

What is used to connect polypeptide chains together?

Answer 3

Peptide bond

Question 4

What is the smallest functional protein?

Answer 4

A tripeptide called thyrotropin-releasing hormone

Question 5

How many amino acids are there from which proteins are made?

Answer 5

20

Question 6

What is the structure of an amino acid?

Answer 6

• COOH
• NH2
• H
• R (side chain)

Question 7

Are proteins D or L isomers?

Answer 7

L- amino acids

Question 8

Where are D-isomers found?

Answer 8

In bacterial cell walls

Question 9

What does cationic mean?

Answer 9

Positively charged

Question 10

What does anionic mean?

Answer 10

Negatively charged

Question 11

What does dipolar mean?

Answer 11

No charge

Question 12

Can a neutral AA contribute to buffering?

Answer 12

Cannot contribute to buffering as cannot ionise

Question 13

Can acidic and basic AA contribute to buffering?

Answer 13

Can contribute to buffering as they can ionise

Question 14

What is electronegativity?

Answer 14

The power of an atom to attract electrons towards itself

Question 15

What are polar R groups?

Answer 15

Hydrophilic due to presence at pH7 of full positive or negative charge in R group (polar, CHARGED) or partial changes in permanent-dipole bonds in non ionisable R groups (polar, UNCHARGED)

Question 16

What are hydrophobic AA?

Answer 16

Many non-polar bonds, so equal share of electrons so no positive or negative charges

Question 17

What are post-synthetic modifications of amino acid side chains?

Answer 17

Can add a hydroxyl group, carboxylic group or a phosphate

Question 18

What is the primary structure of a protein?

Answer 18

The AA sequence

Question 19

What is the secondary structure of a protein?

Answer 19

• Arrangement in space of AA close to one another

- Interaction between the hydrogens in the polypeptide chain

Question 20

What is the tertiary structure of a protein?

Answer 20

Interactions between R groups which fold the protein into a compact 3D-shape

Question 21

What is the quaternary structure of a protein?

Answer 21

Interactions between multiple polypeptide chains acting together