Proteins

Question 1

Name the various classes of amino acids

Answer 1

Aliphatic e.g Alanine
Aromatic e.g Phenylalanine
Sulfur containing e.g Methionine

Basic e.g Arginine
Acidic e.g Aspartate
Polar e.g Serine

Miscillaneous e.g Proline

Question 2

Describe the functions of proteins

Answer 2

Structural
Enzymatic
Contractile
Receptor
Defensive
Hormonal
Storage
Transport

Question 3

What is meant by primary structure?

Answer 3

The first level of structure in which amino acids are bonded together to form a polypetide chain

Question 4

What kind of bonds are found in the primary structure?

Answer 4

Peptide

Question 5

What is meant by secondary structure?

Answer 5

The second level of structure referring to the 3D arrangement of amino acids located near each other in the polypeptide chain

Question 6

What kind of bonds are found in the secondary structure?

Answer 6

Hydrogen bond

…between the amino hydrogen of one amino acid and the carboxyl oxygen of another

Question 7

State the two types of secondary structures

Answer 7

Alpha helix e.g troponin
Beta pleated sheet e.g porins

Question 8

What is meant by tertiary structure

Answer 8

The third level of structure in which the R chains of amino acids interact with one another

Question 9

Why is tertiary structure significant?

Answer 9

A protein must exist as atleast a tertiary structure to be functional

Question 10

What is meant by quaternary structure?

Answer 10

The fourth level of structure in which multiple polypeptides interact with one another to form a quaternary structure

e.g haemoglobin

Question 11

Name the 3 types of conjugated proteins

Answer 11

Glycoproteins
Lipoproteins
Metalloproteins

Question 12

Describe the function of a glycoprotein

Answer 12

Proteins with one or more carbohydrate molecules attached

Most commonly used for cell signalling but also useful in stability, solubility and orientation

Question 13

Describe the function of a lipoprotein

Answer 13

Proteins that combine with lipids

Found in cell membranes and transport hydropobic molecules

Question 14

Describe the function of a metalloprotein

Answer 14

Proteins with a metal ion in their structure

They can be used as enzymes, signal transductors or for transport and storage

e.g haemoglobin

Question 15

Describe the difference in structure between firbous and globular proteins

Answer 15

Fibrous proteins are composed of long narrow strands

Globular proteins are more round and compact

Question 16

Describe the difference in function between firbous and globular proteins

Answer 16

Firbrous proteins have a structural role
e.g muscle, connective tissue

Globular proteins habe a functional role
e.g enzymes, transport, storage