2.1.2 Biological Molecules - Proteins

Question 1

What are proteins?

Answer 1

proteins are made from long chains of amino acids

Question 2

Monomer to protein?

Answer 2

1 unit = amino acid (monomer)
2 units = dipeptide
2 or more units = polypeptide
1 or more polypeptides = protein

Question 3

What do all proteins contain?

Answer 3

• Amine group (-NH2)

- Carboxyl group (-COOH)

Question 4

What elements do all proteins contain?

Answer 4

carbon, hydrogen, oxygen, and nitrogen

Question 5

What bonds join up amino acids?

Answer 5

Peptide bonds (-CONH-)

Question 6

Primary structure?

Answer 6

the sequence of amino acids in a polypeptide chain

Question 7

Secondary Structure?

Answer 7

Hydrogen bonds form between nearby amino acids in the chain.
This causes the chain to start to coil or fold.
EXAMPLES: alpha helix and beta pleated sheet

Question 8

Tertiary Structure?

Answer 8

The secondary structure is coiled or folded even more.
(more bonds form between the different parts of the polypeptide chains).
Final 3D structure for proteins made from a single polypeptide chain.

Question 9

Quaternary structure?

Answer 9

several different polypeptide chains held together by bonds

e.g. Haemoglobin

Question 10

What are the different bonds? (weakest to strongest)

Answer 10

hydrogen bonds
hydrophilic and hydrophobic bonds
Ionic bonds ( - and + R group attractions)
Disulfide bonds (between sulfur)

Question 11

Globular proteins?

Answer 11

compact, water-soluble, and usually roughly spherical in shape.
e.g. Insulin, Haemoglobin

Question 12

Fibrous proteins?

Answer 12

Fibrous proteins are formed from long, insoluble molecules.

e.g. Keratin, Elastin, Collagen

Question 13

What is a prosthetic group?

Answer 13

a non-protein component of a quaternary structure protein

Question 14

What is a conjugated protein?

Answer 14

globular proteins that contain a non-protein component.

Question 15

Haemoglobin

Answer 15

• Quaternary structure
• Contains a prosthetic group, Haem (which contains Iron II)
• made of 4 subunits / polypeptide chains, 2 of which are different
• each subunit contains a prosthetic haem group
• The iron II ions present in the haem groups are each able to combine reversibly with an oxygen molecule, this enables haemoglobin to transport oxygen around the body. (basically: Haem (prosthetic group contains Fe2+ which oxygen binds to)
• hydrophilic R-groups on the outside, hydrophobic R-groups on the inside which makes globular proteins soluble.

ROLE: to carry/transport oxygen around the body

Question 16

Fibrous proteins example

Answer 16

Collagen - connective tissue, skin and muscles
(strong)
Keratin - skin, hair, nails
(flexible or hard and tough)
Elastin - skin, large blood vessels and some ligaments
(elastic connective tissue)