2. mutations

Question 1

what causes mutations

Answer 1

any change in genetic structure in DNA or chromosome is called a mutation

if a change in genotype results in a change of phenotype then that organism is called an mutant.

it can give rise to brand new alleles & can be a major source of variation within a population.

there are chemical agents & radiation that can induce mutations e.g mustard gas, UV light, gamma rays.

Question 2

chromosome mutations

Answer 2

chromosomes mutations are either changes in the number of chromosomes, or in the structure of individual chromosomes involving more than one gene

Question 3

what causes chromosome mutations

Answer 3

a change in chromosome number is caused by failure of spindle fibres during meosis.

Question 4

what causes chromosome mutations

Answer 4

NON DISJUNCTION - a change in chromosome number is caused by failure of spindle fibres during meiosis.

Question 5

chromosome mutations (change in structure )

( change in chromosome numbers)

Answer 5

deletion - chromosome breaks into two & portion is lost.
e.g deletion of the short arm of chromosome 5 leads to “cri du chat” -> lethal

duplication - segment of one homologous pairs becomes attached to its partner-> genes being repeated.

translocation - section of chromosome breaks off & attaches to another which is not its homologous partner.

inversion - chromosome breaks in two places, the broken segment turns around and reattaches.

polyploidy - gametes with extra sets of chromosomes when fertilised give rise to polyploid individual.

Question 6

alteration of base type or sequence

Answer 6

this involves alterations in the bases of DNA or RNA.

insertion, deletion - called frameshift mutations and these lead to major changes as whole sequences of DNA are misread.
This has a major effect on the protein produced.