• Understand the difference between genetic conditions and genetic disorders.
  • Describe genetic disorders involving autosomal and sex-linked inheritance.
  • Perform laboratory simulations to explore heterozygous advantage.


Alkaptonuria is a condition in which urine is passed as a black inky substance
This is caused by non-functioning genes which normally produce an enzyme that converts the black urine to its usual colour

Tay-Sachs diseases is an autosomal recessive disorder
Children with Tay-Sachs appear normal at birth but at about eight months of age the brain and spinal cord begin to deteriorate causing blindness, mental handicap, and show little muscular activity
Most children with Tay-Sachs die before five years
Individuals with Tay-Sachs lack an enzyme in the lysosomes of their brain cells
The recessive allele does not code for the production of the enzyme responsible for breaking down specific lipids in the lysosomes
As undigested lipids build up the lysosomes become enlarged and eventually destroy the brain cells that house them