FSQA_6600DE_Lecture_2_Audio_audio (1)

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Hello, my name's Keith Warriner and from

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the earlier unit one you talk about the history of food

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

science in general and Doctor Who really outlined

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

how this was of interaction between chemistry,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

a bit of engineering and eventually microbiology.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So in a lot of senses microbiology is the newer of the sciences compared

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

to the sort of physical.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

engineering and the chemistry so when people look

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

at science you always think everything's being discovered but

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

in reality especially in the case of microbiology because it's so young

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

is that there's a lot to discover.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But rather than going through the world of discovery,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

we're going to talk about the basics here.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And the way to treat these lectures is that they're

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

kind of an alternative to the reading material.

1:01

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So some people like to learn by reading books and

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

chapters and things like that.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Some people like to learn by taking notes.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Other people just are very visual.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and they like to look at lectures and that's what we've all been brought up to

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

do. So think of this as a supplemental alternative

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

to the reading material because

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

it covers the points that were in the reading material but it's a bit more

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

concise and that's how to treat it.

1:32

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

All right,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

so without much more ado then,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

we're going to talk about evolution of microbes and what affects

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

their growth and how they survive in this world.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Because understanding the evolution of microbes really

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

helps us understand how they adapt it to certain environments.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And when we talk about certain environments,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

obviously in this course we're interested in the food environment.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Obviously there's different environments.

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S… Speaker 2 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So what we're going to be doing...

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

is going through to outline the different modes

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

of evolution.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So a lot of you might be thinking,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

well, there's only one type of evolution.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

It's Darwinism,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

isn't it?

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But, you know,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

it's not quite as clear cut.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And we're going to look at the different types of microbes associated

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

with food.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

It's not going to go deep into this because there's thousands and thousands

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

of different microbes.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Well, hundreds of thousands of different microbes.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the thing about microbiology is the um in the old olden days my

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

day i suppose it is is that we used to have to learn

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

names of bacteria and just had lists and lists of them but that's

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

not really the point i think i think the important point is saying

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

how did these microbes adapt to the environment what do they do to that environment is it

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

positive or is it negative like pathogens so we're

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

going to talk about that we're going to talk about difference between gram positive and gram negative and

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

then we're going to talk about what affects the growth of microbes and we

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

call them intrinsic factors that's associated with the food itself and extrinsic

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

which is the environment around the food and then we'll talk about where

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

uh microbes come from we'll talk about the primary secondary environment so

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

primary environment so they're what they're adapted to this is what

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

they evolved to inhabit secondary environments are where

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

they kind of survive now

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

some microbes can do very well in primary and secondary but

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

other microbes like salmonella for example yes it can grow under

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

certain conditions but then have to survive under those other

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

conditions which are so conducive but we'll talk about that towards the end all

3:43

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

right so let's go way back when um

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

4 .5 billion years ago,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the Earth started forming.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

As we know, it's all these meteors and everything coming together to make this

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

rock of molten iron,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

which then evolved further and things like that.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And eventually life formed now.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Obviously,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

nobody was there to record the start of life.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And there's a lot of disputes about where's the early sign of life,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

because what's happening is that as research continues...

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

we start thinking that life started much earlier

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

than we anticipated.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So the old kind of view is that if the sort

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

of clock was a 24 -hour clock,

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S… Speaker 3 (FSQA_6600DE_Lecture_2_Audio_audio (1))

you know,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

humans would appear.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

30 seconds before midnight.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But the first sort of microbes,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

they thought,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

kind of developed 20 minutes after the start of the Earth.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But people disputed.

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S… Speaker 4 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Nobody was there.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

No fossil records,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

obviously, are kept.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So it's one of those mysteries of life.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And when we look at the start of life,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

what triggered it,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

there's different theories.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And why it started is a totally different sort

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

of theory. That's more philosophical,

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S… Speaker 4 (FSQA_6600DE_Lecture_2_Audio_audio (1))

I suppose.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But...

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

The classic kind of force,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

isn't it, is that what we have is these tidal flats.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So these tidal flats are like seashores.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So they get dry,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

they go wet,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

they get alkali,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

they get acid.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Yeah, because the sea back then,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

it wasn't pleasant.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

It was very alkali.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

A lot of ammonia and other things.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

You had acids being formed and things like that.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

The suggestion is that changing chemistry between low

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

pH, high pH,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

hot,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

cold, and all these things,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and obviously the building blocks,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

kind of got these microbes together,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

all these molecules together to make the first kind of nuclear castles,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

which then developed into life.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So that's the classic sort of theory.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But obviously...

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Because we're scientists,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

we have other theories,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

isn't it?

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And my favourite theory is the Panisperium.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So what this is basically suggesting is that

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

life came via meteorites.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So it was preformed and it exceeded the Earth.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And the reason why I think this theory has actually got a bit of

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

credence is a few factors.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

One is that if you go to the upper atmosphere...

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

you can find microbes there.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And the thing is,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

those microbes don't have pollen associated with them.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And what people are deducing from that is saying it's not just a case

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

of them floating up to the stratosphere.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

It's actually formed there.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And there was an interesting article about life on Venus

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

saying it's in the clouds.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Obviously, it won't be any time soon we'll know that.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But panisperium,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

in a lot of ways,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

makes sense in that it seeds the Earth,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and obviously,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

like seeds,

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S… Speaker 5 (FSQA_6600DE_Lecture_2_Audio_audio (1))

it grew and grew.

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S… Speaker 2 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Now,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

neopanisperium is another interesting one.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

This means there wasn't a seeding event,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

a not single event.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

It was constant.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

They were constantly bombarded with microbes from outer space.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

You know,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

obviously, the conspiracy theory suggests a certain virus

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

came from that way.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Who'd know?

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But Neopanospirium is basically where we have

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

a constant bombardment of microbes.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Obviously, some survive,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

some don't survive,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and that's how we get such diversification.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

I suppose if you wanted to have some credence to that,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the reality is we only can culture 5 %

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

of the microbes,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and they suggest...

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

95 % we haven't discovered yet because

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

of this unculturability.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So,

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S… Speaker 4 (FSQA_6600DE_Lecture_2_Audio_audio (1))

again,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

you know,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

everyone's got a theory about it and all this kind of thing,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

but I think it illustrates how little we know.

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S… Speaker 6 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Now,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

linked to that is the life on Mars.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So what the sort of theory goes like is that...

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Mars was inhabited first by microbes and,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

who knows, Martians even.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And obviously,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

meteors hit that.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

It's like a cue ball.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

It splits off.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And one of those sort of fragments managed to get to the Earth

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

to seed it,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and we're all Martians.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So we're trying to go to Mars to live on Mars,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

where we've been there before,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

apparently.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Anyways,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

that's one theory.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

The other theory,

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S… Speaker 4 (FSQA_6600DE_Lecture_2_Audio_audio (1))

which, again,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

is the old school,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

is the hypothermic springs.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So here,

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

obviously, they come from the inner earth and

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

it's full of sulfur,

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ammonia,

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heat and all this kind of thing.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And life evolved around these springs.

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S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

It had the chemistry to make them macromolecules and assembled

8:35

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

into microbes.

8:36

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So the sort of spring vents

8:40

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

or the hot springs,

8:41

S… Speaker 4 (FSQA_6600DE_Lecture_2_Audio_audio (1))

again, is one of those theories that,

8:43

S… Speaker 3 (FSQA_6600DE_Lecture_2_Audio_audio (1))

yes, it is.

8:45

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And the other theory is the island volcano.

8:50

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So a bit like the hot springs,

8:51

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

except on land.

8:52

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Basically,

8:53

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

you get these eruptions with sulfur,

8:54

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

ammonia,

8:55

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

carbon,

8:56

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and all these kind of come together to produce the macromolecules that produce

9:01

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

light.

9:01

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And six is a nuclear geyser,

9:03

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

which again is on the similar thing in that there was one spot on Earth

9:08

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

where life could...

9:09

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

take place because one of the sort of paradoxes as i mentioned is that

9:14

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the oceans back then were very toxic you could imagine full of

9:18

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

sulfur full of ammonia god knows what else and like and what

9:22

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the theory goes is that there was just this one kind of spot on

9:26

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the earth don't ask me where it is which had all the conditions

9:30

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

that was conducive to life and from that obviously things

9:34

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

changed on the world and that's where life come from so

9:38

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

The reality is nobody really knows what will happen.

9:41

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

I suppose you could find evidence if you go out to outer space and find...

9:45

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Well, I think this is why they're interested in the Martian life,

9:47

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

isn't it?

9:48

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Because if the same microbes are on Mars and were here,

9:51

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

then that's pretty good definite proof,

9:54

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

isn't it, of something?

9:55

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But anyway,

9:56

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

that's life.

9:57

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

We'll keep going.

10:00

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So we've got our seeding,

10:01

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

but obviously just having molecules there,

10:04

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

like ammonia,

10:05

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

sulphur,

10:06

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

nitrogen,

10:06

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

carbon,

10:09

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

you have to assemble them in some way to make them organised.

10:15

S… Speaker 3 (FSQA_6600DE_Lecture_2_Audio_audio (1))

One of the sort of,

10:17

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

again,

10:18

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

this uncertainty,

10:19

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and there's no way of knowing which is true or false,

10:21

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

is saying,

10:22

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

well, how did it survive?

10:23

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So what happened first?

10:25

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Like, what was the first macromolecule?

10:27

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So obviously you've got the people who believe in nucleic

10:31

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

acids, because obviously we know that they have the blueprint of life,

10:35

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

they have the genes and that to encode for enzymes and

10:39

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

cell structures.

10:41

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and they can store data and replicate that's the kind of thing isn't it of that life actually

10:45

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

is and they suggest rna was actually the first nucleic

10:50

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

acid because obviously it can be transcribed uh dna

10:54

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

followed because it's more stable but then other sort of uh

10:58

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

four paddies well maybe it was the proteins because proteins are stable they

11:02

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

can reproduce to a degree when we talk about prions like prions are associated

11:07

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

with mad cow disease

11:09

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And they kind of reproduce,

11:11

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

but it's more a conversion.

11:13

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So it's not a reproduction per se.

11:15

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

It's converting good proteins into bad proteins.

11:19

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And obviously the catalytic,

11:21

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

because you've got to generate energy.

11:22

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

You've got to be able to build cell structures.

11:24

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So nucleic acids can kind of do that because they do

11:29

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

exhibit enzyme -like activity.

11:32

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

whereas obviously proteins have enzyme activity.

11:34

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So again,

11:36

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the four pattern is,

11:37

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and consensus is the key in terms of what people

11:41

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

believe in the science,

11:42

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

is RNA started,

11:44

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

that came to proteins,

11:45

S… Speaker 3 (FSQA_6600DE_Lecture_2_Audio_audio (1))

then it came to DNA.

11:46

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So the fact is,

11:50

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

then, what we had is that we had this assembly of monomers

11:55

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

which turned into these macromolecules.

11:57

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So we have proteins.

12:00

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

phospholipids,

12:00

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

obviously fatty acids to make a membrane,

12:03

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the carbohydrates to make polysaccharides,

12:07

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and nucleic acids.

12:09

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And what these did is assemble into what we call these

12:13

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

oil droplets.

12:14

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So it's interesting this.

12:16

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So what people believe is that we had this chemistry going on producing

12:20

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

these amino acids that went into proteins.

12:23

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But the reality is you needed this sort of...

12:27

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

vacuole this sort of contained chemistry to make a cell and

12:31

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the theory goes is that

12:33

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

The lipid membranes formed first to contain all these reactions,

12:37

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and then the proteins developed,

12:39

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

nucleic acids developed,

12:40

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and these were the first rudimentary cells.

12:43

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And,

12:44

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

you know, people say,

12:45

S… Speaker 4 (FSQA_6600DE_Lecture_2_Audio_audio (1))

oh, well, you know,

12:46

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

why would it do that?

12:47

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But there was an interesting set of experiments done with this responsive oil droplet.

12:51

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So, not to go too deep into it and digress,

12:54

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

is that these oil droplets are made of free fatty acids,

12:58

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and when they're put in a solution...

13:01

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and you put carbohydrates or an acid at one end of them they

13:05

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

swim towards it you know it's uh i think it's a parlor game but but

13:09

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the reality was is that these were responsive and you can see a youtube video

13:14

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

if you look at it and what the theory goes is that this container chemistry

13:18

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

that we add the nucleic acids and then what was happening

13:22

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

these nucleic acids were being transferred to other vesicles

13:26

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

you know manually bumping into each other and it's quite interesting in these experiments

13:30

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

with the lipid droplets is that when they put several in they

13:35

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

start sharing kind of the content so to speak which

13:39

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

is interesting to see they kind of coalesce as well but to the point is that they start

13:44

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

showing this nuclear cast information which is always replicating and things like that

13:48

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

and from that point obviously

13:51

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

The viruses evolved from that.

13:53

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So they said,

13:54

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

well, it's randomness.

13:56

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But then for some reason,

13:57

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

like I say,

13:58

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

when you think about it,

13:59

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

there's no reason why it should happen at all,

14:00

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

is that the first viruses started to transfer the DNA much more specifically.

14:05

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And what was happening is that the viruses were encoding

14:09

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

for other viruses.

14:10

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So you were starting to replicate.

14:12

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

viruses and that made for stability it made for evolution

14:17

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

because rather than random events now you know basically the virus wants

14:21

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

to replicate itself and it'll take other sort of pieces of

14:25

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

dna as extra to put into the growing genome and

14:29

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

that's how they think life again now again you know it's all theory isn't it

14:35

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So the common theory is that it's all to do with chemistry,

14:38

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

but it's self -contained chemistry within the lipid,

14:40

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the self -assembly.

14:41

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

We've got the proteins from the proteins.

14:44

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

We had enzymes.

14:45

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

We had metabolic pathways.

14:46

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And with these metabolic pathways,

14:50

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

what the theory goes at is that it's a

14:54

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

means for microbes to spread.

14:55

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So let's take the hyperperfect.

15:00

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the vents yeah the hot vents up springs so what's

15:04

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

happening is that the microbes were living on there they

15:08

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

were sulfur reducing probably and they were getting all the nutrients needed from

15:12

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

the vents and things like that so it didn't need to move but you

15:16

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

could imagine it's competitive and microbes wanted to get away from the vents you

15:20

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

know to spread and explore the world so

15:24

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

To do that,

15:25

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

they had to do a certain evolutionary steps.

15:27

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And these evolutionary steps means that they had to increase stability.

15:31

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So these lipid vesicles had to be increased stability in order to

15:35

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

survive the harshness of the real world.

15:38

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

They had to generate their own energy,

15:40

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

which basically arose the metabolic pathways.

15:43

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

No longer can they just simply use the chemistry of a hot spring.

15:46

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

They had to have metabolic pathways like glycolysis.

15:51

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

they had to adapt to these different environments,

15:54

S… Speaker 7 (FSQA_6600DE_Lecture_2_Audio_audio (1))

hot, cold,

15:55

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

acid, alkali,

15:56

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

different carbon sources and things like that.

15:59

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So this is a theory where lipid vesicles went

16:04

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

from these sort of little vesicles into the wide world.

16:08

S… Speaker 6 (FSQA_6600DE_Lecture_2_Audio_audio (1))

Now,

16:09

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

evidence to suggest that came from the archaebacteria.

16:15

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So the archaebacteria are very ancient bacteria.

16:17

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

They're here today,

16:19

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

so they must have done something right,

16:21

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

isn't it?

16:21

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And this is different from the other bacteria

16:25

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

we know.

16:26

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

These are very primitive.

16:28

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

They have what we call pseudomurin as a...

16:32

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

sort of cell wall rather than back to the glycos we know.

16:35

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So these make a different branch.

16:36

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

What's interesting about these archaebacteria,

16:40

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

a lot of them are streamophiles.

16:42

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

They can stand high heat,

16:44

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

high salinity,

16:45

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

high sulfur,

16:46

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

high salt,

16:47

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

high methane.

16:48

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

And really that shows you where they evolved from.

16:52

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

You could imagine this hostile new world with all the sulfur and everything like

16:56

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

that.

16:56

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So obviously the archaebacteria...

16:59

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

had this niche this niche of a hot spring and things like that but

17:04

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

other bacterias the earth kind of settled down a bit they

17:08

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

kept they became more adapted they went they branched off and the soul wall was key

17:12

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

to that but we'll talk about that in a bit

17:16

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So obviously the next big step then is that we've got our metabolic pathways

17:20

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

now, and that's fine.

17:22

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

But then we had this split between gram -positive and gram -negative.

17:26

S… Speaker 1 (FSQA_6600DE_Lecture_2_Audio_audio (1))

So as the bacteria started,

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or micro,

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started to fill the niches,

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there were different stresses.

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With the gram positives,

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we have a very thick peptidoglycan cell wall,

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which we'll talk about later,

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out of the membrane.

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Where the gram negatives have what we call a lipopolysaccharide,

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LPS.

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And what this LPS functions as

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is a few things.

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One of them...

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is a selective barrier.

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So what you'll find is that when we think

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about things like sanitizers,

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antibiotics,

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the gram negatives are more resistant because they've got this physical barrier,

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this sort of gateway that these chemicals have to pass,

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whereas the gram positives are totally exposed.

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There's no sort of protection.

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So what you'll find as a rule,

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and it's a rule of thumb,

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there's always exceptions,

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is gram positives are very...

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stable to heat and high extreme phs whereas

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gram negatives are more stable to antimicrobial

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agents so alkali strips off this lps

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layer alcohol strips off this lps layer and they've got a very thin

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peptidoglycan which makes them sensitive to heat makes them sensitive

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to desiccation i think it's like that but just saying that as i mentioned there's always

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exceptions and

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The first person to actually differentiate between gram -positive

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and gram -negative was Christian Graham,

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who wanted to differentiate bacteria.

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He was playing with some stains at the time,

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and he was adding iodine to a cell culture,

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and he was asking crystal violet.

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And when iodine and crystal violet get together...

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they produced a purple colour,

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and he designated them as gram -positive.

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Now,

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in a gram stain,

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when you've got your crystal violet and your iodine,

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they can't penetrate the gram -negative cell wall.

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So what happens is that,

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if you remember,

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if you've ever done a gram stain,

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you add alcohol to it,

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strips away the LPS layer,

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and you can't stain with saffronin,

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and then you appear pink.

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when you look at the microscope you see pink cells uh pink cells

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as gram negative and purple ones as gram positive now

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what came first again is totally um speculation

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um because there's no fossil records but what people believe

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is that the gram positive came first because that had to tolerate

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these extreme conditions

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of desiccation and thermal.

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The gram negatives came later because obviously they were getting

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bombarded with antimicrobials and things like that.

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But again,

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who knows if it's true or not.

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So as I mentioned to you,

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gram negative and gram positive,

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with gram negatives you have LPS.

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That comes really significant when we talk about pathogens and

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antigens and things like that.

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they're more resistant to things like antibiotics and sanitizers,

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whereas the grand positives,

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they're more...

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resistant to thermal processing like lysteria compared

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to e .coli salmonella much more firmly resistant and they're very good at desiccation

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resistance now as i mentioned to you there's exceptions to rules for

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example coronabacter and salmonella are very tolerant to desiccation

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as well but certainly with these the

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gram positives are much more adapted to ph because as i mentioned to you alkali

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ph strips off the lps layer

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and that's how they used to differentiate the two.

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Now, there is other forms of cells,

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and that's called the L -form bacteria.

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So,

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as I mentioned to you,

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the cell wall,

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in a lot of ways,

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was the secret to life.

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That's really where life came from.

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It's not...

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Well, I'm sorry, nuclear gases are on their part,

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but the cell wall was really for the rigidity

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and survivability of cells.

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But after saying that,

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L -form bacteria lack all cell walls,

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and they can have gram -positive,

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gram -negative L -form bacteria.

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So...

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What some people think is just a relic of the past.

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So some cells are replicating and just forget to produce

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a cell wall.

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It's a mutation.

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But interestingly,

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these L -form bacteria are much more resistant to antibiotics,

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firmly resistant,

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and they're much more likely to go to a dormant state,

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which is more resistant.

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So what people think is that...

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These are hedge betting.

FSQA_6600DE_Lecture_2_Audio_audio (1)

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