Bread Mold Kills Bacteria How the penicillin in bread mold kills bacteria.
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- Microorganisms are small. So small you can't even see them unless they cluster together.
- Each of these dots is really millions of bacteria.
- But down at a microscopic scale, mold and bacteria fight vicious battles.
- Their resources and territory are scarce
- and the stakes are survival.
- Mold has a powerful chemical weapon in its arsenal.
- I'm Emily, and I'd like to show you Alexander Fleming's famous
- discovery that bread mold kills bacteria.
- Here's some fresh bread.
- I'll add some water because mold loves moisture.
- Now I need bacteria, which you can find basically anywhere,
- including in your mouth.
- This petri dish has a jello-like layer of agar:
- food for the bacteria in my saliva.
- It'll take a few days before the colonies of bacteria are big enough to see.
- Let's set up a place to grow the mold and bacteria in a contained way, so it doesn't spread or infect anything else.
- These bell jars will help make sure that
- nothing contaminates the experiment,
- and the experiment doesn't contaminate anything else.
- I'm back!
- Wow! There's a lot of bacteria!
- Each cell divided and divided and divided to make a colony
- that we can see now.
- Some bread mold also grew.
- Let's see if it can kill some bacteria.
- I'll take a chunk of bread mold and let it do its work.
- Legend has it that in Fleming's original experiment,
- some mold from his lunch sandwich accidentally dropped into his petri dish.
- Let's take a closer look,
- and we'll come back later and see what's changed.
- Under a microscope mold looks something like this yellow model,
- and mold attacks bacteria cell walls, represented by these cups.
- Mold secretes a chemical: penicillin,
- which damages bacteria cell walls, stamping out the competition.
- This means the bacteria surrounding the mold will die.
- We're looking for bacterial death around the mold.
- Do you see where the bacteria have died around the mold?
- This is called the ring of death.
- Mold and bacteria have been battling for millions of years.
- Mold keeps coming up with new weapons: antibiotics;
- and bacteria keeps coming up with new shields: resistance.
- Alexander Fleming, after treating wounded soldiers in World War One, was the first person
- to realize how useful antibiotics are for treating infection.
- Today we remember him for his discovery of penicillin.
- I think his experiment is really neat, and I hope you do, too.
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At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?
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