3.1 GENES

Question 1

Gene

Answer 1

A sequence of DNA that encodes for a specific trait

It is a heritable factor that consists of a length of DNA and influences a specific characteristic of an organism

Question 1

Locus

Answer 1

The position of a gene on a particular chromosome

Question 2

Allele

Answer 2

variations of the same gene

they are formed by mutations

Question 3

Mutation

Answer 3

is a permanent change in the base sequence of DNA

Question 4

Genome

Answer 4

is the whole of the genetic information of an organism

Question 5

Sickle cell mutation - malaria

Answer 5

It is a base-substitution mutation where the change in a single base results in a different amino acid being produced in the polypeptide

1. The DNA sequence changes from GAG to GTG on the non-transcribed strand
2. The mRNA sequence changes from GAG to GUG at the 6th codon position
3. The sixth amino acid for the beta chain of haemoglobin is changed from glutamic acid to valine (Glu to Val)
4. The amino acid change (Glu → Val) alters the structure of haemoglobin, causing it to form insoluble fibrous strands changing the shape of the red blood cell to a sickle shape
5. The sickle cells may form clots within the capillaries, blocking blood supply to vital organs and causing myriad health issues
6. The sickle cells are also destroyed more rapidly than normal cells, leading to a low red blood cell count (anaemia)