Case 10

Case 10
Learning goals:
1. Different types of mutation
2. How are mutations caused?
3. Methods to make a phylogenetic tree




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, 1. Different types of mutations
Three types of mutations:
1. Point mutations: change in one or a few base pairs
2. Chromosomal mutations: change in a whole chromosome or sections
of them
3. Gene mutations: affects the function of genes and so the
phenotype.


Point mutations
Types:
- Insertion
- Deletion
- Substitution
- Inversion


Effects of substitutions:
- Transition: a purine-pyrimidine base pair  another purine-
pyrimidine base pair
o A-T  G-C OR G-C  A-T
- Transversion: a purine-pyrimidine base pair  pyrimidine-purine
base pair
o A-T  C-G OR G-C  T-A
- Missense: different amino acid is inserted into the polypeptide
- Nonsense: an mRNA codon is changed into a stop codon
- Neutral (conservative): a change in a codon, but results in no
change in the function of the protein
- Silent: a change in a codon, but that codon results in the same
amino acid as the first one


Effects of insertions/deletions:
- Frameshift: there is an addition or selection which results in a
change in the reading frame




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