Key Area 1.4: Essay Questions

Question 1

Describe the effects of names single gene mutations on the amino acid sequences in proteins they code for

Answer 1

• substitution invoked swapping one nucleotide for another
• substitutions can be missense in which a change in one codon results in a different amino acid being used
• substitutions can be nonsense in which a codon is changed to a stop codon making the protein shorter
• deletion incomes the removal of a nucleotide from the sequence
• insertion involves the addition of a nucleotide to the sequence
• deletion/insertion give frameshift effects to amino acid sequence in the protein
• frameshift mutations lead to many amino acids being changed, which has a major effect on protein structure

Question 2

Give an account of the types of structural mutation to chromosomes and their effects

Answer 2

• deletion
• involves loss of a section from a chromosome
• translocation
• involves a section from one chromosome joining to another
• duplication
• invoked a section from one chromosome being copied within the chromosome

Question 3

Give an account of mutation on health under the following headings:

a) Sickle cell disease
b) Haemophilia

Answer 3

a) - caused by substitution in the gene coding for haemoglobin
- abnormal haemoglobin produced causes blood cells collapse during exercise
- collapsed cells can’t carry oxygen, leading to breathlessness
- collapsed cells become trapped in capillaries, producing pain
b) - caused by mutation in the gene coding for blood clotting factor
- absence of normal clotting factor causes failure of blood to clot
- excessive bleeding occurs from cuts
- excessive blood loss can be fatal