Chapter 4 - Gene expression and Regulation Flashcards
What is gene regulation?
The process of controlling which genes are expressed and the rate of which they are expressed
What are the two types of gene?
Regulatory genes and structural genes
What do regulatory genes code for?
transcription factors needed for transcription to occur
What do structural genes code for?
codes for proteins that aren’t used in gene regulation
What is an example of gene regulation?
lac operon model
What does the lac operon model contain?
- three different genes
- a single promotor region
- an operator
What is the lac operon model responsible for?
responsible for breaking down lactose into glucose and galactose
What does lacL code for?
it codes for the repressor protein
What is the operator region responsible for?
it is the binding sit for the repressor protein. the repressor protein acts like and on and off switch
What are the structural genes?
- code for different enzymes involved in digestion of lactose
- share the same promotor region
- transcription of these genes can be switched on and off
Why are structural genes switched on and off?
synthesising proteins that aren’t needed by the cell is a waste of energy
What happens when lactose is not present?
structural genes are repressed (switched off)
What happens when lactose is present?
structural genes are induced (switched on)
What does the repressor protein do?
It binds to the operon and blocks RNA polymerase from transcribing the genes
How does the lac operon model function when lactose is present?
the repressor protein binds to any lac repressor protein which stops the lac repressors from binding to the operator
