Question

a) Explain different types of gene and chromosome mutation

b) Explain the possible causes of gene and chromosome mutation

c) Judge why gene mutations are often less severe than chromosome mutations.

Answer 1

a) The different types of chromosome mutations are deletions (deletion of DNA segment), duplications (formation of duplicate copies of DNA piece), inversion (a chromosome segment gets reversed) and translocation (rearrangement of parts between non-homologous chromosome) of chromosome. Gene mutation can be missense (change in one DNA base pair) and nonsense (a sense codon is changed to a chain terminating codon).

b) Environmental factors such as UV radiation or cemical mutagens can cause mutation. Error in DNA copying and error in rearrangement of chromosome parts at the time of meiosis also cause gene and chromosome mutations.

c) Chromosome mutations affect several genes whereas gene mutation affects a single gene. Chromosome mutations are structural or numerical changes in the entire DNA. Hence, chromosome mutations are more severe as compared to gene mutations.