Proteins

Question 1

Name 7 types of Amino Acid

Answer 1

• Aliphatic
• Aromatic
• Uncharged Polar
• Other (Proline)
• Sulphur containing
• Acidic
• Basic

Question 2

Explain an Aliphatic Amino Acid

Answer 2

R group is made up of straight or branched carbon chains

Question 3

Explain an aromatic Amino Acid

Answer 3

R group contains Phenyl (benzene) groups

Question 4

Explain an uncharged Polar Amino Acid

Answer 4

R group is uncharged but polar so has a localised charge making them capable of hydrogen bonding and hydrophilic

Question 5

Explain Acidic Amino Acids

Answer 5

Contains COOH groups which can lose protons making them acidic

Question 6

Explain Basic Amino Acids

Answer 6

Contain Nitrogen groups that resemble ammonia and can accept protons making them basic

Question 7

Define Primary Protein Structure

Answer 7

The sequence of amino acid residues in a linear polypeptide chain

Question 8

Define Secondary Protein Structure

Answer 8

The spatial arrangement of amino acid residues close to eachother in the linear polypeptide chain.

Question 9

Name two structures created by arrangement of the secondary structure

Answer 9

The Alpha Helix and Beta Pleated sheets

Question 10

What links amino acid residues in the secondary structure?

Answer 10

Hyrdogen Bonds

Question 11

Define Tertiary Structure

Answer 11

The spatial arrangement of amino acid residues far apart in the linear polypeptide chain.

Question 12

What forces hold the tertiary structure in place?

Answer 12

• Numerous, weak van der waals forces
• Hydrogen Bonds
• Rare but strong ionic interaction between oppositely charged ions
• Disulphide bridges, covalent bonds between sulphur ions in two cysteine residues
• Hydrophobic interactions, intra-polypeptide interactions which occur in an enviroment within proteins in which water is excluded. Cause the protein to coil up so the hydrophobic residues face inward and teh hydrophilic outward.

Question 13

Define Quaternary Structure

Answer 13

The spatial arrangement of individual polypeptide chains in a multi-subunit protein

Question 14

How does denaturation affect protein stucture?

Answer 14

It can disrupt or break bonds in the secondary and tertiary structures, changing the shape and function of the protein. However it is not strong enough to break peptide bonds so the primary structure is unaffected.

Question 15

Name 6 causes of Denaturation

Answer 15

Heat
Acid
Solvents
Crosslinking reagents (formaldehyde)
Chaotropic agents (Urea)
Disulphide bond reducers.

Question 16

Name 4 effects of Denaturation

Answer 16

Improved Digestibility
Reduced water binding capability
Loss of biological activity
Decreased Solubility

Question 17

Define a Glycoprotein

Answer 17

A compound composed of a protein and a carbohydrate. Glycosylation where a sugar molecule binds to an amino acid in the protein.

Question 18

What are the 5 roles of Glycoproteins?

Answer 18

Protein Stabilisation
Signalling
Cell recognition
Affects Solubility
Protein Orientation

Question 19

Define a metalloprotein

Answer 19

A protein molecule with a bound metal ion such as haemoglobin

Question 20

Name 4 roles of metalloproteins

Answer 20

Transport
Enzymes
Signalling
Storage

Question 21

Define a Lipoprotein

Answer 21

A protein bound covently or non-covently to lipids.

Question 22

Whats the function of lipoproteins?

Answer 22

To transport not water soluble fats and cholestorol around the blood stream.

Question 23

Define Co-operative binding

Answer 23

In a multi-subunit protein binding to one of the chains causes the shape of the others to alter making it easier for them to bind.

Question 24

Name the 5 functions of globular Proteins

Answer 24

• Enzymes
• Hormones
• Transporters
• AMino acid stocks
• Structural

Question 25

Name the 4 structural functions of fibrous proteins

Answer 25

Bone Matrices
Muscle Fibre
tendons
Connective Tissue

Question 26

Compare the structures of Globular and Firbous proteins

Answer 26

Globular proteins are made up of interwoven polypeptide chains.
Fibrous proteins are made up of helixes formed from polypeptide chains wound round more helixes to form strong fibres and held together by H bonds.

Question 27

Explain 4 Properties of Collagen

Answer 27

• Fibrous Protein
• Makes up 25% of our prtein
• High tensile Strength
• is made from a glycine-X-proline repeating unit