All language subtitles for FractionatingLife 4

PROFESSOR: Welcome back.

So, lecture two.

We're going to now dive into our triangle.

As I told you about in the last lecture, the entire course is

organized around our coat of arms, the coat of arms function being

understood two ways.

Biochemistry, genetics.

Fundamentally studying the most interesting and richest molecules,

proteins, but we'll talk about other kinds of molecules.

Genes, the object of study of geneticists, and the

connection of the two.

But today we're going to start with understanding this picture by

beginning several lectures on biochemistry.

All right.

Biochemistry.

Again, you have to put yourself back in the mindset.

To understand how science is done you have to think about what discoveries

meant to the people who were discovering them and what was so

surprising.

So put yourself back in the mindset of somebody just before the turn of the

20th century.

They knew about phenomena.

I'll tell you about a phenomenon that they knew about, that you've

probably heard of.

Fermentation.

A popular subject, for example.

I'll name this section in a moment.

If you take a glass filled with sugar water or fruit juice, and you just

leave it sitting out just at room temperature, over the course of some

days, you'll begin to see bubbles develop.

Sugar water, fruit juice, bubbles develop and come out and you will also

find that if you try to drink it, you've made alcohol.

This is, of course, the basis of beer, wine.

That bit of bubbles is also the basis of bread.

So this is an observation as old as the hills, that if you take sugar

water or fruit juice and you leave it sitting out, you develop bubbles.

The bubbles were known to be carbon dioxide and alcohol came out of it.

And this carbon dioxide drives the production of bread.

That's where you can have bread rise.

And the alcohol.

You get beer, you get wine.

You also had one other very strange thing, another product.

In addition to the production of carbon dioxide and the production of

alcohol, people noticed that the thing got cloudy.

And this is cloudy stuff that also seemed to be produced from this sugar

water was yeast.

For a long time people thought the yeast was a product of fermentation.

They didn't know that yeast was a living organism.

They didn't know it was a cell.

They thought it was a product of fermentation.

And it took some pretty clever science to show that the yeast was not a

result of fermentation, it was the cause of the fermentation.

Because there was a little bit of yeast there, it produces fermentation

and it grows and divides and makes more and more yeast cells, and the

yeast is the cause.

So Pasteur was involved in showing that you needed living organisms there

in order to produce the fermentation.

Fermentation, ferment, from the Latin [LATIN]

to boil.

The bubbles coming off there.

Really cool stuff.

The problem was they got into their heads so solidly that you needed this

living organism yeast to do the fermentation that people began to ask,

was this something only living matter could do?

Now the chemists at the time, in the 1700s and the

1800s, were really curious.

This looked like chemistry.

You were taking sugar, you were producing carbon dioxide and alcohols.

How could this be made to work?

Did you need a living organism to do it?

People worked really hard to try to somehow extract from the living

organism something capable of doing fermentation

without a living organism.

And they failed miserably.

Miserably.

They tried sodium hydroxide treatment of this yeast and see if they could

extract things.

They tried boiling it at high temperatures to extract things.

They tried letting it sit for days and then whatever they did the resulting

goop that they got could not do fermentation.

You might now guess that the reason they couldn't do fermentation is they

had managed, with their harsh treatment of high temperatures and

sodium hydroxide and other things like that, to have destroyed that which

might carry out fermentation.

But that was not the conclusion in the late 1800s.

The conclusion was that fermentation, this miraculous transformation that

life could carry out, was inherently only possible because of a living

organism being present.

It was inherently necessary to have living protoplasm to do this.

It was not chemistry, it was beyond chemistry.

It was some vitalism.

And it was referred to as vital forces, vitalism, the idea that in

addition to the laws of physics and the laws of chemistry there were these

other properties that life had that couldn't be understood as chemistry.

And that was pretty much the view up until the 1890s.

As late as the 1890s this idea that there was some magic living things

could do was still holding sway.

That was called vitalism, this concept.

And what I want to start talking about is the death of vitalism.

It turns out that vitalism came because nobody could manage to get

something that could do this fermentation.

If you could somehow show that you could extract the thing that could

ferment without the need of the organism, that would be a big deal.

A guy called Eduard Buchner came along and, for a variety of reasons I won't

go into, but in the mid-1890s said, you know, maybe we should try to be a

little more gentle with this yeast thing.

And, as so often happens in science, it was technology that drove it.

He invented powerful new technology.

He invented this powerful technology right here.

The powerful technology that he invented was first this thing here.

A long mortar hanging and a little pestle here in which he could put the

yeast, add some sand, some quartz, little particles of sand, and swing

this thing around very gently.

And the little sand would crack open the yeast and the yeast would become

kind of a doughy, gray, mushy mixture.

And he only did that for a couple of minutes, just going around and around

and around.

Then what he did was he scooped it off and he put it in a piece of canvas.

And he covered canvas up into a little package and he stuffed

it into this press.

And he turns to press and squeezes out yeast juice.

And remarkably, the yeast juice was able to carry out fermentation.

Now he had to convince people that it wasn't that a whole lot of cells had

somehow gotten in the yeast juice.

So he had to convince people that there weren't cells there.

And he showed there really weren't cells there, or not very many cells.

And even a few cells getting in wouldn't be a problem,

because it was so active.

It was doing so much fermentation it couldn't be accounted for by a couple

little strays cells.

So he had to be very scientific about it.

But he eventually publishes in 1897 that this yeast juice can carry out

fermentation.

The stuff that carried out fermentation was referred to as, you

know, something from yeast.

The Latin name here referring to yeast is zyme.

The thing that was in yeast was called an enzyme.

There were enzymes.

Something in yeast.

They didn't quite know what it was.

And these enzyme or enzymes could carry out this miraculous

transformation.

Well, Buchner like knocked everybody's socks off with this.

And, amongst other things, Buchner wins the Nobel prize

for this for chemistry.

Nobel prize in chemistry for the year in 1907.

One of the first Nobel prizes, the seventh Nobel prize given in chemistry

goes to Buchner for this landmark thing.

Now, I got to say, this whole notion is so remarkable that I went back and

pulled out Buchner's Nobel lecture 1907 in which when he gets invited to

Sweden on December 10 for Alfred Nobel's birthday and gives a

talk and all that.

It's still so cool.

And we have on the web in the resource box associated with the course

Buchner's lecture.

I'm just going to read you a little bit from the end of Buchner's lecture.

Because on the one hand he's so excited that they understand this, and

on the other hand he realizes, boy, we hardly know anything.

Like, I can't tell you what these enzymes are at all.

We've managed to show that yeast juice can do this.

We don't need a living organism.

Vitalism isn't right.

But boy, I have no clue what's going on.

And so honest here.

It's wonderful.

"Distinguished audience," he says in his closing remarks, "as you'll see,

we are still far from an understanding of the processes involved in alcohol

fermentation of sugar, as well as from a more detailed description of the

nature of the zymes" which he also was using for enzyme.

"Quite the contrary, every step we take the present leads to fresh

complications.

We must be thankful, however, if the increasingly narrow and steep paths do

not end in an unclimbable cliff." He had no idea that they'd ever be able

to understand what these enzymes were about.

He goes on for a little bit, and he says, "Nevertheless, there is no cause

for discouragement.

The progress made in the field of fermentation processes is clearly

revealed when you compare our present knowledge with that of just a few

decades ago.

The differences between the vitalistic view and the enzyme theory have been

reconciled.

The fermentation process becomes comprehensible to us now that it is

possible to separate it from the rest of the processes of life.

Just as the first step toward the explanation of the phenomenon of

combustion rested on the fact that it was possible to separate the

generation of light and heat from the processes of oxidation." He's thinking

about this in a very broad sense.

And he says, "We are seeing the cells of plants and animals more and more

clearly as chemical factories where the various products are manufactured

in separate workshops." A very industrial revolution

kind if view here.

"The enzymes act as the overseers." What a factory view of

the late 1800s here.

"Our acquaintance with these most important agents of living things is

constantly increasing.

Even though we may still be a long way from our goal, we are approaching it

step by step.

Everything is justifying our hopes.

We must never therefore let ourselves fall into the way of thinking

ignorabimus, we shall never know.

But we must have every confidence that the day will dawn with even those

processes of life, which are still a puzzle today, will cease to be

inaccessible to us natural scientists."

That's one hell of a way to end a Nobel lecture.

And it's a statement about what is amazing about science was that it all

seemed unimaginable that we were ever going to understand what those enzymes

were about at essentially the turn of the 20th century.

And of course you know perfectly well we do know, and we're going to cover

in the next couple of lectures what all of that is about.

And all the things we don't understand today, you can just apply Buchner to

that as well.

So all right, that's where we are.

Buchner the death of vitalism, and now we've got actually dive in and

understand how all that stuff works.

What are those enzymes?

Can we understand these amazing properties of life?

Properties of being able to carry out chemical transformations, properties

of being able to, oh, I don't know, even more simple things.

Having cells in the first place.

Membranes around cells.

How in the world you do that?

Like, what makes a membrane the divides a cell's

inside from its outside?

How you do other sorts of things?

Can we understand all of those things in terms of fundamental chemistry?

That's what biochemistry's asking us here.

So before we go on to the next segment, test

yourself with this problem.