Checking your understanding of operons

All classes are registering for AP tests at the computer lab during the block day.

Class began with a short check of your understanding of operons.  This was followed by an assessment to see how students manipulated their lac operon models in response to environmental conditions.

We discussed the positive regulation of the lac operon, as described in 18.4.  Key points:

• Lactose is a secondary energy source that will only be used when glucose is low.
• CAP is an activator of the lac operon.
• CAP will only work if cAMP is bound to it.
• Low levels of glucose lead to high levels of cAMP and therefore, high levels of active CAP.
• Without CAP, even if the repressor is inactive, the lac operon will transcribe only in very small amounts.

HOMEWORK
Classes were split into groups of four.  Group members then numbered off 1-4.  Based on your number you are to read a section of 19.2 to read and then teach to your group in class on Friday.  If you were ABSENT for class, please read the section for group member 2.

Student number 1: Regulation of chromatin structure.  Special focus on histone modifications and DNA methylation.

Student number 2: Regulation of transcription initiation.  Special focus on transcription factors, enhancers/activators/repressors and coordinately controlled genes.

Student number 3: RNA processing and mRNA degradation

Student number 4: Initiation of translation and protein processing and degradation