32 - MCB 142 Professor Georjana Barnes 11/09/07 Lecture 32...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
MCB 142 Professor Georjana Barnes 11/09/07 Lecture 32 ASUC Lecture Notes Online (formerly Black Lightning) is the only authorized note-taking service at UC Berkeley. Please do not share, copy or illegally distribute these notes. Our non-profit, student-run program depends on your individual subscription for its continued existence. These notes are copyrighted by the University of California and are for your personal use only. Sharing or copying these notes is illegal and could end note taking for this course ANNOUNCEMENTS I want to make two announcements. One is that some of your colleagues have requested that I post on bspace the night before the lectures in whatever shape they are in. I’ll do that as long as you realize that the lectures are not in finalized form and might change. The other thing is that on the website, under Handout section, there’s a handout from Monday lecture and one that covers today and Wednesday with concepts that are critical to understand LECTURE REVIEW OF LAC OPERON This is the lac operon which we talked about on Wednesday. It has stretches of DNA that involve the coding sequences for genes involved in the metabolism of lactose. There’s a regulatory region that’s in cis (connected) to these structural genes. And then there’s a repressor (dotted line, which shows that the repressor is not connected physically to the operon). The repressor binds to the operator site in regulatory region in trans (at a distance) and this action shuts down the expression of those genes. This is an example of a catabolic pathway, which means that it’s usually off because a catabolic pathway involves breaking stuff down into useful subunits and lactose is not always around and not the preferred catabolite. When lactose is present, there is an induction of the expression of the genes regulated by the lac operon. So there’s an inducer that binds to the repressor and the complex of repressor- inducer is no longer able to bind to the operator to prevent transcription and so now, transcription is possible in the presence of the inducer. OTHER POSSIBLE SUBSTRATES AND INDUCERS What is new today are the possible inducers and possible substrates. The reason I’m going into this is because an understanding of the regulation of the lac operon and of the function of the lacZ gene is useful because the lacZ gene and the lac operon are very useful tools in modern genetics and for studying various biology problems. Lactose is an inducer (orange blob) but there are other possible inducers that have been discovered over the years that will induce the lac operon. One of those is IPTG. IPTG mimics the induction capacity of lactose by binding to the repressor; the repressor-bound IPTG won’t bind to the operator and there is induction of the genes connected to the regulatory region. The good thing about IPTG from an
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/04/2008 for the course MCB 142 taught by Professor Slatkin during the Fall '08 term at University of California, Berkeley.

Page1 / 7

32 - MCB 142 Professor Georjana Barnes 11/09/07 Lecture 32...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online