1. Phenotype affected by
mutations
• Mutation – an unpredictable change in
the genetic material of an organism
• Gene mutation – change in the structure
of a DNA molecule, producing a different
allele of a gene
• Chromosome mutation – changes in
the structure or number of whole
chromosomes in a cell
ALBIO9700/2006JK

2. Mutation factors
(mutagen):
• Ionising radiation (alpha, beta and gamma
radiation)
• Ultraviolet radiation
• Chemicals (mustard gas)
ALBIO9700/2006JK

3. Types of mutations
• Base substitution
Silent mutation
eg. CCT GAG GAG to CCT GTG GAG
• Base addition
eg. CCT GAG GAG to CCA TGA GGA G
Frame shift
• Base deletion
eg. CCT GAG GAG to CCG AGG AG
ALBIO9700/2006JK

4. ALBIO9700/2006JK

5. Examples of phenotype
change caused by mutation
• Sickle cell anaemia
• Phenylketonuria
ALBIO9700/2006JK

6. ALBIO9700/2006JK

7. Phenotype affected by
environment
• Genotype of the organism does not always
affect its phenotype in the same way
• Eg. i) Human height
ii) Dark tips to ears, nose, paws and tail in
the Himalayan colouring in rabbits
iii) lac operon in Escherichia coli
ALBIO9700/2006JK

8. ALBIO9700/2006JK

9. ALBIO9700/2006JK

10. ALBIO9700/2006JK