Chromosome structure mutations

Question 1

Chromosome structure mutations

Answer 1

Alteration to the whole sections of chromosomes, affecting several genes as a result of;
Duplication, Deletion, inversion or translocation

Question 2

Chromosome structure mutation - duplication

Answer 2

A section of a chromosomes becomes attached to its matching (homologous) chromosome- leading to repeated genes.
Example - proto-oncogenes can become oncogenes due to gene duplication - these oncogenes have high potential to cause cancer.

Question 3

Evolutionary importance of gene duplication

Answer 3

Duplication of a gene produces a second copy of the gene which is free from selection pressure - it can become altered by single gene mutation without affecting the original genes which produces the protein as normal.
These duplicated genes which could mutate to produce new DNA sequences which could in turn confer a positive advantage to the organism and increase its fitness and chance of survival.

Question 4

Chromosomes structure mutation - deletion

Answer 4

Section of the chromosome is removed as a region of DNA (or multiple) is left out during replication- therefore some genes are deleted.
Example - Cri du Chat syndrome.

Question 5

Chromosome structure mutation - inversion

Answer 5

Chromosome breaks in two places and rotates 180°. The sequence of the genes in this section are reversed.
Often results in non viable gametes since the chromosome pairing cannot occur.

Question 6

Chromosome structure mutation - translocation

Answer 6

A section of a chromosome becomes attached to a different chromosome (not its chromosome homologous partner)
This results in problems pairing chromosomes during gamete formation and lead to non viable gametes.

Question 7

Effect of chromosome mutations

Answer 7

The substantial changes in chromosome mutations often make them lethal.