Homework SoursePredict the level of GAL1 transcription in the presence of g
Solution
1. Effect on GAL1 transcription, in presence of glucose alone of the following mutations.
1. Normal wild- type yeast : activate transcription
2. Deletion of the GAL1 gene from the yeast genome: activatee transcription
3. Deletion of the GAL4 gene from the yeast genome: not activate transcription
4. Deletion of the GAL80 gene from the yeast genome: not activate transcription
5. Deletion of the GAL3 gene from the yeast genome activate transcription
6. Deletion of the MIG1 gene from the yeast genome: not activate transcription
Effect on GAL1 transcription, in presence of galactose alone, of the following mutations.
1. Deletion of GAL1 UAS elements : small active transcription
2. Deletion of the GAL1 promoter : prevent transcription of gene
3. Deletion of the GAL4 gene from the yeast genome: loss of one GAL4 binding site from the GAL1 UAS element may have small effect on GAL4 transcription
4. Deletion of the GAL80 gene from the yeast genome: no effect on transcription of GAL1 in the presence of galactose.
5. Deletion of the GAL3 gene from the yeast genome: not active GAL1 transcription.
6. Deletion of the MIG1 gene from the yeast genome : activate transcription of GAL1
2. Compare the regulation of the lac operon in bacteria and the GAL 1 transcription in yeast:
1. Signal integration: ensures that certain gene are switched on or off only when the proper combination of two or more signals present eg: we have seen the combination of an activator and a repressor used to integrate two signal in bacteria and yeast.
2. Combinatorial control : eg: CAP works on some 200 genes in addition to the lac genes. CAP works with GAL repressor to control transcription of the gal genes in E.coli, the products of which metabolize galactose.
