[03] Amino Acids, Peptides, and Proteins

Question 1

What are amino acids?

Answer 1

Organic molecules that serve as the building blocks for proteins.

Question 2

How many common amino acids are there?

Answer 2

20

Question 3

What are the three key elements of an amino acid structure?

Answer 3

• Amino group (-NH2)
• Carboxyl group (-COOH)
• Side chain (R group)

Question 4

How are amino acids classified?

Answer 4

Based on the properties of their side chains: nonpolar, polar but uncharged, positively charged, and negatively charged.

Question 5

Give examples of nonpolar amino acids.

Answer 5

• Glycine (Gly)
• Alanine (Ala)
• Valine (Val)
• Leucine (Leu)
• Isoleucine (Ile)

Question 6

Gly - Initials

Answer 6

Glycine

Question 7

Ala - Initials

Answer 7

Alanine

Question 8

Val - Initials

Answer 8

Valine

Question 9

Leu - Initials

Answer 9

Leucine

Question 10

Ile - Initials

Answer 10

Isoleucine

Question 11

What is a peptide bond?

Answer 11

A covalent bond formed between two amino acids when the carboxyl group of one reacts with the amino group of another, releasing a molecule of water.

Question 12

What is a peptide?

Answer 12

A molecule consisting of two or more amino acids linked by peptide bonds.

Question 13

What is a protein?

Answer 13

A large molecule composed of one or more chains of amino acids in a specific order; the order is determined by the base sequence of nucleotides in the gene that codes for the protein.

Question 14

What determines the function of a protein?

Answer 14

Its shape and structure, which is primarily determined by its amino acid sequence.

Question 15

What are the four levels of protein structure?

Answer 15

• Primary structure
• Secondary structure
• Tertiary structure
• Quaternary structure

Question 16

Define the primary structure of a protein.

Answer 16

The sequence of amino acids in a protein; it dictates the protein’s higher-level structures and function.

Question 17

What are the two types of secondary protein structure?

Answer 17

Alpha helix and beta sheet.

Question 18

What is the tertiary structure of a protein?

Answer 18

The three-dimensional shape of a protein, determined by interactions among various side chains (R groups) of amino acids.

Question 19

What is the quaternary structure of a protein?

Answer 19

The structure resulting from the association of two or more polypeptide chains (subunits) into one functional protein.

Question 20

How can a protein lose its function?

Answer 20

If it becomes denatured, which means its structure is altered and it loses its correct shape.