Module 6, Section 1: Cellular control.

What is ‘gene expression’?

The way different proteins are switched ‘on/off’, thus modifying the proteins that specific cell codes for.

How can Gene expression be controlled at the transcriptional level?

Using transcription factors.

How do transcription factors regulate gene expression?

They bind to DNA, and thus decrease/increase the rate of transcription..

What can affect the function of transcription factors?

The presence of molecules such as hormones and sugars.

What are operons?

A section of DNA in prokaryotes that transcription factors bind to and thus prevent or allow a certain gene from being coded for.

How is the lac operon an example of transcriptional level control?

In absence of lactose, the regulatory gene produces the lac repressor, which prevents the protein needed for the respiration of lactose.

However, in the presence of lactose, the lac repressor binds with lactose, and the RNA polymerase can now bind to the gene.

How can gene expression be controlled post-transcriptionally?

By editing the mRNA. There are sections of non-coding DNA in eukaryotes that can be removed without changing structure of the protein, called introns.