04 Phenotype Change Mutation and Environment
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Mutations are changes in genetic material that can occur at the gene or chromosome level. They can be caused by mutagens like radiation or chemicals and result in changes like base substitutions, additions, or deletions. Different types of mutations can lead to silent changes or shift the reading frame, resulting in different phenotypes like sickle cell anemia or phenylketonuria. However, the environment can also influence the phenotype even with the same genotype, as seen with factors affecting human height, rabbit fur color, and gene expression in E. coli.
04 Phenotype Change Mutation and Environment
- 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
- 5. Examples of phenotype change caused by mutation Sickle cell anaemia Phenylketonuria 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
- 10. ALBIO9700/2006JK