1. Pleiotropy

2. Definition
The ability of a gene to affect more than one characteristic. A
Several characteristics are affected
by the single gene B C

3. Sickle cell disease The gene Hb codes for production of haemoglobin.
Hbs is a mutation.
Mutant haemoglobin results in:
Brain damage
Heart and blood vessel damage
Spleen enlargement then atrophy
Kidney damage leading to blood in urine

4. PKU (phenylketonuria)
The PKU gene codes for the enzyme phenylalanine hydroxylase.
This enzyme converts the phenylalanine to tyrosine. Both are amino acids.
Mutations to the gene result in:
Mental retardation
Reduced hair and skin pigmentation
Damage to body parts from toxic levels of phenylalanine
PKU is totally benign if a diet free from phenylalanine is maintained.

5. Fruit fly and vestigial wing
The vestigial gene plays a critical role in wing development.
vv will develop short wings
The affects are:
Cannot fly
Number of egg strings in a fly's ovaries changes
Position of bristles on a fly's scutellum alters,
Length of a fly's life decreases

6. Pigmentation and deafness in cats
About 40% of cats with white fur and blue eyes are deaf
The gene affects pigmentation as well as ability to hear
Pigmentation may play a role in maintaining fluid in ear canals