Third lecture

Our third lecture with Prof Katty was on mutation. Mutation is any inheritable change in the base sequence of DNA. It can be spontaneous (occurs without a mutagen)  or induced (chemical and physical agents to induced the mutation) .

Types of Mutations:

Base substitutions (a single base at one point in the DNA sequence is replace with a different base) There are three types under this mutation which are silent, missense, nonsense.

Frameshift mutation: insertion or deletion, shift in the reading frame

Types of mutagens: base analogues, chemical mutagen, radiation, intercalating agents.

To identify mutants, detection by selecting or testing for an altered phenotype. Two kinds which are nonselectable and selectable ( positive selection and negative selection).  

Positive (direct) selection- isolate mutants that require amino acids or other growth factors (parent cannot grow)

Negative(indirect selection)- nutritional mutant, inability to grow in agar plate lacking the nutrient (parent grow). 

Well basically this is the summary of this morning class.