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  • [ Silence ]

  • >> Okay, welcome back.

  • Quick sound check.

  • Everything okay?

  • Great, thank you.

  • Welcome back.

  • Today, we're going to be finishing up the topic

  • that we were talking about last time.

  • Last time, we were talking about combinatorial approaches

  • in chemistry and then we'll talk a little bit more

  • about combinatorial approaches in biology.

  • And I'll show you a couple of examples of this.

  • All right.

  • Okay, that's interesting.

  • All right.

  • Okay, so again we're here.

  • We just completed our survey of biomolecules.

  • I'm going to complete the topic of making combinations

  • of biomolecules and then we'll talk

  • about tools for chemical biology.

  • And this is really important because these are the tools

  • that you're going to be using when you write your proposals.

  • So I'm glad you're all here today

  • because you absolutely need to hear this to be able

  • to write a good chemical biology proposal which recall last time,

  • I told you was going to substitute

  • for the final exam in this class.

  • There is no final exam in this class.

  • We will not have a final.

  • Instead on the very last day of class,

  • you will hand me a 10-page or so proposal, a written proposal

  • with figures and it'll be an original idea,

  • something that no one in the planet has thought of before.

  • You will be the first.

  • And it's going to be really fun because it's really great

  • to come up with creative ideas

  • and that's really the ultimate goal of science.

  • Science is really a creative enterprise.

  • Our goals are to invent new concepts,

  • to tell people new visions of the universe and to do this;

  • we have to somehow invent these new experiments to do.

  • Okay, so I'm going to be talking to you today about the tools

  • in your toolkit that you're going to be using

  • to do this assignment.

  • Okay, I already talked about these announcements.

  • I'm skipping some stuff.

  • Oh, office hours.

  • I had office hours yesterday that got derailed

  • by a student emergency and I know at least one

  • of you sent me an email about that.

  • I apologize.

  • I will have office hours today and in addition,

  • I sent an email back to that student.

  • So I apologize if you came by yesterday.

  • There was a student health emergency

  • that absolutely needed my attention and so I had

  • to close my door to deal with that.

  • Okay, so apologies there.

  • Other office hours, tomorrow, Mariam will have her office hour

  • on Friday and I'm hoping Kritika will be back next week

  • and I'll introduce you to her

  • and she'll have office hours next Tuesday.

  • Okay, so all right, any questions about any

  • of the announcements, things like that,

  • things that we talked about last time?

  • Questions about the course structure?

  • Oh, I got an email from someone

  • and I apologize for not replying.

  • The email was, "When are you going to post online the slides

  • that I'm flicking through?"

  • And the answer is I'm going to try to get to that today.

  • And then my plan is to basically post all of my slides

  • from the previous year and so that way,

  • then at least you'll have a guideline

  • for what the slides will look like.

  • Chances are, I'll heavily modify these

  • or slightly modify these depending

  • on how much time I have before each lecture.

  • I mean, literally five minutes before the lecture,

  • I was making changes to the slides.

  • It's almost impossible to stop me from doing that.

  • I just love this too much.

  • So because of that, I'll be posting kind of a guideline

  • for what the slides will look like in advance.

  • And then I'll come back

  • with something that's more definitive.

  • Okay, so at the end of today's lecture, then I'll post all

  • of the week one slides in a definitive way

  • but I'm also going to post last year's week two,

  • week three, week four, et cetera.

  • Okay, sound good?

  • Okay, any questions about that?

  • Okay, great.

  • Okay so let me review what we talked about last time.

  • If there are no questions about any announcements or things

  • like that, we're going to go straight into the material.

  • Okay, good.

  • So what we talked about last time was the definition

  • of chemical biology.

  • Chemical biology uses techniques from chemistry,

  • often new techniques from chemistry, often techniques

  • that had been invented specifically to answer problems

  • of biology but not always.

  • And then these techniques from chemistry are used

  • to address understanding biological systems

  • at the level of atoms and bonds.

  • That's the goal of chemical biology,

  • to really understand how organisms are living,

  • how they do the things they do at the level of atoms and bonds.

  • Okay, so I'm really fascinated to know

  • about that hydroxide functional grid

  • that donates a key hydrogen bond or provides a key Bronsted acid

  • to some mechanism in an enzyme-active site.

  • That's the part that makes run to work,

  • the sort of the details of this.

  • I basically want to use the arrow pushing that you learned

  • in sophomore organic chemistry to explain biology

  • and that's the goal of this class

  • and that's the definition of chemical biology.

  • So last time, we learned about two key principles

  • that organized biology.

  • The first of these is essential dogma which provides the roadmap

  • for all biosynthesis taking place inside the cell.

  • Everything that the cell has to synthesize will flow

  • through this central dogma.

  • This is the flow of information for biosynthesis by the cell.

  • So everything that your cells will synthesize is going

  • to be encoded in some way by the DNA inside your cells.

  • Oh, and can I ask you if you have an empty seat next to you

  • to move over to the right just to open

  • up some seats on the edges.

  • Some people I know are coming in from other classes so you know,

  • so other classes that are ending

  • about when our class is starting.

  • So if you have an empty seat on your right,

  • if you can just scooch over and leave seats on the edge,

  • that would be really appreciated.

  • Okay, thank you.

  • Okay, so the second key principle

  • that we discussed was evolution.

  • Evolution provides a principle

  • that helps us organize vast amounts of knowledge and really

  • in the end simplifies biology enormously.

  • And it's actually a principle that all of you are going

  • to be applying when you design your chemical

  • biology experiments.

  • Because I will tell you in advance

  • that I will not accept any proposals

  • that involve experiments on humans, okay?

  • So experimenting on humans has its own special topic

  • that I can actually teach a whole quarter on.

  • Okay, it requires ethical considerations.

  • It requires tremendous design considerations.

  • It's not nontrivial to sample, for example,

  • a diverse population of humans and ensure

  • that you're getting diversity.

  • So all of those considerations are beyond the realm

  • of this class.

  • So instead, what I'm going to ask you to do is experiment

  • on non-human organisms.

  • You might for example choose cells from humans

  • or you might choose model organisms.

  • And by choosing those model organisms,

  • you're applying a key principle from evolution which is

  • that that model organism descended

  • from some common ancestor that we share and in doing so,

  • acquired the same mechanisms that govern its chemistry

  • and its chemical biology.

  • And so that means, if we learn something

  • about this model organism, we can then apply that knowledge

  • to understanding how humans work.

  • Now naturally, there's limits to this, right?

  • If your model organism is a salamander and you're interested

  • in understanding how the salamander regenerates its arms

  • when you cut them off,