Amino Acids, Proteins and DNA: Amino Acids

Question 1

What functional groups do amino acids contain?

Answer 1

• Carboxyl group

- Amine/amino group

Question 2

Do amino acids have acidic or basic properties?

Answer 2

• Amino acids have both acidic and basic properties

- Known as amphoteric

Question 3

Why can amino acids act as acids?

Answer 3

• Carboxyl group is acidic

- RCOOH

Question 4

Why can amino acids act as bases?

Answer 4

• Amine/amino group is basic

- RNH2

Question 5

Write an equation to demonstrate how amino acids are acidic

Answer 5

• RCOOH ⇌ RCOO- + H+

Question 6

Write an equation to demonstrate how amino acids are basic

Answer 6

• RNH2 +H+ ⇌ RNH3^+

Question 7

Define the term zwitterion

Answer 7

• Dipolar ion

- Molecule has both a positive and negative charge in different parts of the molecule

Question 8

Can amino acids exist as zwitterions?

Answer 8

• Yes

Question 9

When can amino acids exist as zwitterions?

Answer 9

• Near an amino acid’s isoelectric point

Question 10

Define the term isoelectric point

Answer 10

• pH where there is no net charge

Question 11

Does the isoelectric point of different amino acids differ and why?

Answer 11

• Different for different amino acids

- Depends on R-group

Question 12

Draw an amino acid in zwitterion form

Answer 12

• N in NH3 is positive

- O in C-O is negative

Question 13

Draw an amino acid in acidic solution

Answer 13

• N in NH3 is positive

- O in C-O has no charge

Question 14

Draw an amino acid in basic solution

Answer 14

• O in C-O has negative charge

- N in NH2 has no charge