GENE20001 Lecture Notes - Lecture 16: Base Pair, Phosphodiester Bond, Escherichia Coli
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He took a mutant and crossed with a small collection of ordered deletion strains. e. g. he crossed the single mutant with del1 and he got wt. This means mutation is outside this deletion region. Now he was able to narrow down where each of the point mutations were. Could just do a 3 factor cross to work them out. Cold spot is a region where changing the amino acid doesn"t really affect phenotype. Hot spots indicate that mutagens are not random. Mutagens used in the experiment would preferentially mutate certain regions on the dna. e. g. uv tends to dimerise two ts. When this is repaired it needs to be cut out and the incorrect bases may be replaced. Ngt is a mutagen that tends to cause deletions (?) Each mutation that he mapped was the smallest region between which he could separate two mutations. Suggested to him that this was the smallest unit of recombination.
