PoH: Proteins

Question 1

Name the 7 classes of AAs

Answer 1

Aliphatic
Aromatic
Acidic
Basic
Polar
Sulphur-Containing
Miscellaneous

Question 2

What is the difference between an aliphatic and aromatic AA?

Answer 2

In aliphatic, the R group has hydrocarbon chains. In aromatic, the R group has hydrocarbon rings

Question 3

What characterises sulphur-containing AAs?

(bit more specific than “sulphur”!)

Answer 3

A disulfide bridge - covalently bonded linkages between two sulphide-containing AAs which help increase strength

Question 4

What is a polar AA?

Answer 4

Have a charge at the end of the R group

Question 5

What’s the only miscellaneous AA and what’s special about it?

Answer 5

Proline

It has an unusual ring shape and so is incorporated in many tissues needing strength

Question 6

What’s the primary structure?

Answer 6

Amino Acid Residues

The sequence in which AA monomers are bonded together to form a polypeptide chain

Question 7

What’s the secondary structure?

Answer 7

Alpha-Helix

The local spatial arrangement of a polypeptide’s backbone (main chain) atoms. It relies on hydrogen bonding between amino hydrogen of one AA and carboxyl oxygen of another AA. It can be an alpha helix or beta-pleated sheet

Question 8

What’s the tertiary structure

Answer 8

Polypeptide Chain

The 3D structure of an entire polypeptide chain. They happen when the functional groups of ‘R’ chains in AAs interact with each other. They involve Van der Waals, ionic, hydrogen, disulphide bridges and hydrophobic interactions

Question 9

What’s the quaternary structure?

Answer 9

Assembled subunits

The 3D arrangement of the subunits in a multiunit protein

Question 10

In which structures do denaturation occur? Primary, secondary, tertiary and/or quaternary?

Answer 10

Secondary and tertiary

It leads to loss of biological function

Question 11

Name the 8 functions of proteins

Answer 11

Structure
Enzyme
Receptors
Hormones
Transport
Storage
Defence
Contractile

Question 12

Co-translational modification or post-translational modification results in what sort of proteins?

Answer 12

Conjugated proteins (glycoproteins, lipoproteins, metalloproteins)

Question 13

Name the three types of conjugated proteins

Answer 13

Glycoproteins
Lipoproteins
Metalloproteins

Question 14

What are glycoproteins, and what four things does it achieve?

Answer 14

Proteins with 1 or more covalently attached carbohydrates

Stability
Solubility
Cell signalling
Orientation

Question 15

A glycoprotein with a few monomers in a chain is called what?

Answer 15

Oligosaccharide

Question 16

What are lipoproteins? Where are they found? What do they do?

Answer 16

Proteins combined with lipids

Found in cell membranes

Transport hydrophobic molecules (e.g. cholesterol in blood)

Lipoproteins can also form complexes with other lipoproteins, forming apolipoproteins (they transport fats, fat-soluble vitamins and fat soluble hormones)

Question 17

What are apolipoproteins and what do they do?

Answer 17

When lipoproteins form complexes with other lipoproteins.

They transport fats, fat-soluble vitamins and fat soluble hormones?

Question 18

What are metalloproteins and what do they do?

Answer 18

Proteins with metal ions in their structures (co-factors). They include enzymatic, signal transduction, transport and storage.

Question 19

What two ways can proteins be classed on their functions?

Answer 19

Globular and fibrous

Question 20

What 5 functions do globular proteins do?

Answer 20

Storage
Enzymes
Hormones
Transporters
Structure

Question 21

What 2 anatomical features do fibrous proteins do?

Answer 21

Muscle fibres
Connective tissues

Question 22

What 4 things can membrane proteins be, and what do they do?

Answer 22

Membrane transporter
membrane enzymes
cell adhesion molecules
signalling