Chapter 2: Genes and Health

Question 1

Making a dipeptide bond

Answer 1

Condensation reaction- two amino acids join together to release a H2O molecule and a peptide bond is formed

Hydrolysis- addition of water causing the amino acids to spilt

Question 2

Primary Structure of a protein

Answer 2

A linear sequence of amino acids in a protein

Question 3

Secondary structure of a protein

Answer 3

A regular 3D structure formed due to H bonds between H and O of peptide bonds

Alpha helix- polypeptide chain wound to form helix, H bonds run parallel with long helical axis, stable many bonds

Beta sheet- polypeptide chain zig zags back/ forward forming sheets of anti parallel strands, not as strong not as many bonds

Question 4

Amino acid structure

Answer 4

Amino group
Carboxyl group
Residual group

In water H is + and O is - groups ionise

Question 5

Tertiary structure of protein

Answer 5

3D structure of the whole of a peptide chain formed by hydrophobic interactions, hydrogen bonds, ionic bonds and disulphide bonds between R GROUPS

Disulphide (covalent) two cysteine groups

Question 6

Quaternary structure of protein

Answer 6

3D structure of several polypeptide chains joined together

Question 7

Conjugated proteins

Answer 7

Proteins joined together to other non-protein molecules (prosthetic group) eg.haem in HB

Haemoglobin, glycoprotein

Question 8

Globular protein

Answer 8

Complex tertiary structures 
Folded into spherical shapes - hydrophobic outside 
Soluble- hydrophilic on inside 
Often small 
Enzymes, anti bodies, hormones (insulin)

Question 9

Fibrous protein

Answer 9

Very little/ no tertiary structure 
Form long fibres of polypeptide chains 
Insoluble 
Often large 
Very strong 
Structural role- collagen in bones cartilage and tendons