3.1.4.1 Proteins

Question 1

What is the monomer of proteins

Answer 1

• amino acid

Question 2

What chemical properties in proteins change

Answer 2

• non-polar (hydrophobic)
• polar (hydrophilic)
• positive charge (hydrophilic)
• negative charge (hydrophilic)

Question 3

What is the polymer of proteins

Answer 3

• polypeptide

Question 4

How is a polypeptide formed

Answer 4

• condensation reaction
• between amine & carboxyl groups
• forms peptide bond
• water released

Question 5

How do you break a polypeptide

Answer 5

• hydrolysis
• requires water

Question 6

Describe the primary structure of proteins

Answer 6

• sequence of a.a joined by peptide bond
• controls the protein shape
• varied:
  . Different length chains
  . Different a.a in chain
  . Amino aids in different sequences

Question 7

Describe the secondary structure of proteins

Answer 7

• folding of parts of chain - alpha helices or beta-pleated sheets
• due to H2 bonding
• between carboxyl & amino residues

Question 8

Describe the tertiary structure of proteins

Answer 8

• folding into complex, specific, shape
• due to IMF between R groups
• H2 bonds - between polar R groups
• ionic forces - between + and - R groups
• disulphide bridges - covalent bond between cysteine R groups
• London forces - between non-polar R groups

Question 9

describe the quaternary structure of proteins

Answer 9

• holds the polypeptide chains together
• due to IMF between R groups

Question 10

What are the 2 groups of structures in proteins

Answer 10

Globular:
- enzymes, signalling molecules, transport molecules. Have a specific shape for binding

Fibrous:
- structural. Strong & flexible

Question 11

What is the test for proteins

Answer 11

• buret test
• positive result: colour change from blue to purple