BIOLOGY 1A03 Lecture 1: Theme 3: Module 1 - Modulating Transcription

• School: McMaster University
• Department: Biology
• Course: BIOLOGY 1A03
• Professor: Dr.Da Silva

Document Summary

This is where gene regulation becomes important to help prokaryotes respond to their environments. Housekeeping genes: constitutively expressed, they are always being transcribed and translated. Glucose is the carbohydrate that is the preferred energy source of: coli. If we were to expose a bacteria culture to only a limited amount of glucose, we will find that once the glucose is used up, bacterial growth is arrested. 1: since bacteria only metabolize lactose when it is available, it would be a waste of resources to synthesize lactose-metabolizing enzymes in the absence of lactose. However, when lactose is an available nutrient source in the environment and glucose is not available, bacteria are able to quickly upregulate the expression of genes that produce lactose-metabolizing enzymes. As a result, changes in bacterial growth occur over time when bacteria are growing in an environment containing both glucose and lactose. The cell needs to make the enzyme b-galatosidase.