Proteins

Question 1

What are the main classes of protein?

Answer 1

1. Enzyme
2. Signal and Binding
3. Structural
4. Storage

Question 2

What are amino acids?

Answer 2

Monomers that make up protein

Question 3

What makes up amino acids?

Answer 3

amine and carboxyl group with a side chain

Question 4

How many types of amino acids are there?

Answer 4

20

Question 5

What are the charges of all the groups in an amino acid?

Answer 5

amine group - basic, can be protonated to form a positive charge
carboxyl group - can be deprotonated to form a negative charge
side chains - can be deprotonated or protonated

Question 6

What are the amino acids that humans can’t synthesize?

Answer 6

PVT TIM HALL

Phenylaline, Valine, Threonine, Tryptophan, isoleucine, methionine, histidine, leucine, lysine

Question 7

How are peptide bonds formed?

Answer 7

The amine group reacts with the carboxyl group of another amino acid

Question 8

What is a polypeptide

Answer 8

a polymer made up of more than one amino acid

also known as protein

Question 9

What are N-terminus and C-terminus, and what’s the significance of them?

Answer 9

N-terminus refers to the amine group end
C-terminus refers to the carboxyl end
It is to show the directionality of the peptide

Question 10

What is the primary structure of protein?

Answer 10

Linear sequence of amino acids

Question 11

What is the secondary structure of protein, and how is it formed?

Answer 11

• Formed when amino acid side chains interact through hydrophobic or hydrobonding
• alpha helices
• beta strand/sheet

Question 12

Describe the secondary structures of protein

Answer 12

Alpha helices - formed through hydrobonding between N-H group and carboxyl group
- peptide backbone forms the inside of the helix
- side chains face outside
Beta strands/sheets - formed through hydrobonding
- can be parallel or anti parallel
- multiple beta strands form sheets

Question 13

What is the tertiary structure of protein, and how are they formed?

Answer 13

• When a-helix or b-sheets fold into 3d structures
• formed due to distant groups interacting with each other through hydrogen bonding, ion pairing, and disulfide bridges
• driven by the burial of hydrophobic side chains (since cells are aqueous)

Question 14

What are disulfide bonds?

Answer 14

occurs between thiol and cysteine groups where two hydrogen atoms react with an oxygen atom to form water

Question 15

What are quarternary structures

Answer 15

when two or more polypeptide chain come together

Question 16

How are the subunits of the quarternary structures named?

Answer 16

• 2 subunits - dimer
• 3 subunits - trimer
• 4 subunits - tetramer

Question 17

How do you describe a protein made up of same subunit? How do you describe one made up of different subunits?

Answer 17

Same - homodimer

Different - heterodimer

Question 18

What are some factors that denaturizes protein?

Answer 18

• temperature changes
• salt concentration (ion strength
• pH
• presence of redox modulators