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JASON: I can still
smell it on me.

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I took two showers.

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00:00:04,270 --> 00:00:06,582
JULIE: I don't think I ever
smelled bad, so you must have

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00:00:06,582 --> 00:00:08,672
something really wrong.

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[MUSIC PLAYING]

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GUEST SPEAKER: Last time on
5.301, the students made seven

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slightly different versions
of penicillin.

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Today and tomorrow, they'll be
testing which one is best at

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00:00:50,370 --> 00:00:52,070
killing bacteria.

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00:00:52,070 --> 00:00:54,710
They do this by adding seven
different amounts of

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penicillin to a constant
number of E.

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00:00:56,980 --> 00:00:59,320
coli in seven tubes.

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The bacteria will be incubated
for 24 hours, and then the

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students will measure how much
bacteria is left in each tube.

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They'll plot a graph of
bacterial concentration versus

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penicillin concentration.

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This is called a
killing curve.

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The steeper the killing curve,
that better the antibiotic.

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GUEST SPEAKER: Don't
sneeze or anything.

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ETHAN: 7.0 milligrams of
this, and I don't want

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to lose any of it.

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LINA: I think we're
doing really well.

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We're being so careful.

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Everything's working
out perfectly.

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00:01:31,435 --> 00:01:35,610

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GUEST SPEAKER: After a bitter
battle over the biggest

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crystal, Jason and Julie
have made up.

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JASON: She did it.

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She probably spilled it so like,
OK, I have an excuse to

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clean up this and get
away from Jason.

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I didn't say anything.

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JULIE: What did he just
say about me?

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JASON: She hates me.

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She loves me!

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Well, she didn't want
me to say that.

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LEALIA: I think we're
almost done.

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YI-SHIUAN: We're done.

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ANTHONY: You're an
awesome partner.

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TENGFEI: So tomorrow, we're
going to see which tube the

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bacteria grows and which
tube the bacteria dies.

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If they grow, the culture
will become cloudy.

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GUEST SPEAKER: The next day, all
the students have to do is

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measure how many bacteria
are in each tube.

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PROFESSOR: This is how, when you
make a drug candidate, you

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can gauge how effective your
drug candidate is.

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GUEST SPEAKER: To do that, they
use a spectrophotometer,

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which shoots light through the
sample at a detector on the

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other side.

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If there are a lot of bacteria,
most of that light

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is scattered in random
directions and never reaches

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the detector.

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If there are very few bacteria,
most of the light

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makes it through.

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GUEST SPEAKER: Trying to
find the line that

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fits the data well.

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LINA: It feels great, because
I actually know what some of

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these things are.

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At the beginning I had no idea,
so I was asking around

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the entire time.

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So I've learned something
during three weeks.

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ANTHONY: 0.45.

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GUEST SPEAKER: The students plot
the results on the white

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board and discuss whose
penicillin is best.

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00:03:14,001 --> 00:03:17,090

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GUEST SPEAKER: How
are the results?

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ANTHONY: Did I win?

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GUEST SPEAKER: You
tell me who wins.

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GUEST SPEAKER: I win!

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GUEST SPEAKER: Which
is the best?

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GUEST SPEAKER: Yeah,
Anthony's.

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ANTHONY: Mine.

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GUEST SPEAKER: Today is the
students' last day in the lab.

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Tune in to the next episode
to see how 5.301 wraps up.

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GUEST SPEAKER: Just imagine if
you had a president that was a

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bachelor, or if you had a
president with no kids.

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I think that we're going to have
a gay president before we

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have one that doesn't
have a spouse.

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Unthinkable.

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[MUSIC PLAYING-"HAIL
TO THE CHIEF"]

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GUEST SPEAKER: Wait, was he?

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GUEST SPEAKER: Yeah, he was.

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GUEST SPEAKER: He didn't
have a wife?

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GUEST SPEAKER: Nope.

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GUEST SPEAKER: Oh my
god, I'm so stupid.

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I should definitely fact-check
before I talk.

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