Amino acids 48-49

Question 1

Define the term peptide

Answer 1

A peptide is a compound made of amino acids linked by peptide bonds.

Question 2

What are amino acids the building blocks of?

Answer 2

Amino acids are the building blocks for two important groups of biological molecules-peptides and proteins.

Question 3

Give some examples of some proteins and explain their functions.

Answer 3

Proteins act as enzymes, hormones and antibodies. Proteins(polypeptides) transport substances such as oxygen, vitamins and minerals to cells throughout the body. Structural proteins, such as collagen and keratin, are responsible for the formation of bones, teeth, hair and the outer layer of skin, and they help to maintain the structure of blood vessels and other tissues.

Question 4

How man amino acids does the body have?

Answer 4

The body has 20 different amino acids that can be assembled into proteins.

Question 5

What characteristics do σ-amino acids have?

Answer 5

They have a basic amine group and an acidic carboxyl group connected to the same carbon.

Question 6

What are amino acids soluble in?

Answer 6

Amino acids are soluble in both acids and bases.

Question 7

What is the general formula for a-amino acid?

Answer 7

RCH(NH₂)COOH

Question 8

Draw the amino acid glycine.

Answer 8

HCH(NH₂)COOH

Question 9

Draw the structure of 2-aminopropanoic acid (alanine)

Answer 9

(CH₃)H(NH₂)COOH

Question 10

Draw the structure of 2-aminopentanedioic acid(glutamic acid).

Answer 10

(CH₂CH₂COOH)C(H₂N)HCOOH

Question 11

Draw the structure of 2-amino-3-hydroxypropanoic acid (serine)

Answer 11

(CH₂OH)C(H₂N)HCOOH

Question 12

Define zwitterion

Answer 12

A zwitterion is a dipolar ionic form of an amino acid that is formed by the donation of a hydrogen ion from the carboxyl group to the amino group. Because both charges are present, there is no overall charge.

Question 13

Define the term isoelectric point.

Answer 13

The isoelectric point is the pH value at with the amino acid exists as a zwitterion.

Question 14

Draw the formation of a zwitterion from general a-amino acid.

Answer 14

Question 15

What does the term amphoteric mean when applied to amino acids?

Answer 15

Amino acids are amphoteric, which means that they can react with both acids and bases.

Question 16

What happens at a pH more acidic that the isoelectric point to amino acids?

Answer 16

• The amino acid behaves as a base and accepts a proton from the acid.
• The amino acid forms a negatively charged ion.

Question 17

What happens at a pH more alkaline than the isoelectric point of an amino acid?

Answer 17

• The amino acid behaves as an acid and donates a proton to the base.
• The amino acid forms a negatively charged ion.

Question 18

Draw the positive ion formed from an amino acid in acid and the negation ion in alkaline solution.

Answer 18