43 - MCB 142 Professor Georjana Barnes 12/5/07 Lecture 43...

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12/5/07 Lecture 43 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 Office hours today: 12:30-1:30, 301 Barker, Becky’s Wed 11-12pm section will be in 110 Barker today. There will be lecture Friday and next Monday, it’ll be a summarizing lecture. Then I’ll schedule a review session next weekend before the final but I don’t have a room yet so I’ll get that info to you soon. REVIEW Last Monday, we left off at how you can use genetics to understand multi-cellular development. It’s using the same things that we’ve talked about that you already know – altering the cell cycle (lengthening or shortening it), using signal transduction pathways to send messages from one end of the organism to the other, and finally, utilizing how to activate and repress transcription and translation. So it’s just using things we’ve already studied and applying them to looking at how a multi-cellular organism develops. As you know from the beginning of Chapter 20, there are several organisms that people doing genetics prefer to use. Those are Drosophila, worms, zebrafish, plants (Arabidopsis), mice, and yeast is also useful. The reason those organisms are used is because you can do genetics and make mutants that you want to make to ask questions in a way that you couldn’t do with humans. So even though it seems pretty bizarre to think about how Arabidopsis, for example, can give information about human development, all of these organisms can tell us about mammalian development because so much is conserved in the genome from humans down to yeast. The question where we left it last time was ‘how do you know what cells or tissues are affected by the absence of some gene function?’ It’s not always obvious. It’s not the case that if you knock out a gene in this tissue, I’ll see an effect in this tissue. For instance, the pituitary gland has effects on other organs so a mutant in a pituitary gene may not affect the gland at all but the target organ. So in this figure, let’s consider tissue differentiation in Arabidopsis. Here’s a picture of the apical meristem. So these stems will differentiate into flower cells; this is a cross-section. There are three types of cells: L1, L2, L3. There’s a gene called Agamous+ whose wt activity is necessary for L1 cells to differentiate into flower cells. So mutation in Agamous+ will result in lack of flower cells. It turns out when you do the experiment and look at where the Agamous gene function is necessary, it’s not necessary in L1 cells but in L2 cells. Geneticists determined those using mosaic
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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.

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43 - MCB 142 Professor Georjana Barnes 12/5/07 Lecture 43...

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