* Forward genetic: method to see which genes are responsible for which phenotype.
- How it’s done:
1. Choose mutant phenotype.
2. Perform mutagenesis (simple F2, suppressor, enhancer screen).
3. Look for mutants with desired phenotype.
4. Identify gene sequence targeted by mutation.
- Reverse genetic: method to see which phenotype(s) are responsible for which genes.
How it’s done:
1. Choose gene sequence.
2. Disrupt gene function by a variety of approaches (RNAi, ectopic expression,
CRISPR).
3. Characterize mutant phenotype.
- Pleiotropy: creation of ≥ 2 phenotypic traits that are not related from 1 gene.
Consequences of pleiotropy in forward genetics: not all genes can be identified.
Strategy to overcome pleiotropy for reverse genetic: perform multiple tests. When doing
multiple tests, make sure they’re the same as in same gene(s) and method. Then, alter the
new, same tests just a little bit to see if anything changes.
* How to infer WT gene function given a LOF mutant phenotype: compare the WT and mutant
to look for any difference(s). If any are found, make a conclusion.
Ex: WT: , mutant: , (par-)
WT par genes promote asymmetric cell division. NOT par null genes promote symmetric cell
division.
- How it’s done:
1. Choose mutant phenotype.
2. Perform mutagenesis (simple F2, suppressor, enhancer screen).
3. Look for mutants with desired phenotype.
4. Identify gene sequence targeted by mutation.
- Reverse genetic: method to see which phenotype(s) are responsible for which genes.
How it’s done:
1. Choose gene sequence.
2. Disrupt gene function by a variety of approaches (RNAi, ectopic expression,
CRISPR).
3. Characterize mutant phenotype.
- Pleiotropy: creation of ≥ 2 phenotypic traits that are not related from 1 gene.
Consequences of pleiotropy in forward genetics: not all genes can be identified.
Strategy to overcome pleiotropy for reverse genetic: perform multiple tests. When doing
multiple tests, make sure they’re the same as in same gene(s) and method. Then, alter the
new, same tests just a little bit to see if anything changes.
* How to infer WT gene function given a LOF mutant phenotype: compare the WT and mutant
to look for any difference(s). If any are found, make a conclusion.
Ex: WT: , mutant: , (par-)
WT par genes promote asymmetric cell division. NOT par null genes promote symmetric cell
division.
