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  • Intro 0:00
  • Spontaneous Generation 0:04
    • Spontaneous Generation
    • Pseudoscience
    • Individuals Who Sought to Disprove This Theory
  • Francesco Redi's Experiment 3:33
    • 17th Century Italian Scientist
    • Wanted to Debunk the Theory That Maggots Emerge From Rotting Raw Meat
  • Lazzaro Spallanzani's Experiment 6:33
    • 18th Century Italian Scientist
    • Wanted to Demonstrate That Microbes Could Be Airborne
  • Louis Pasteur's Experiment 9:47
    • 19th Century French Scientist
    • Disprove Spontaneous Generation
  • Pasteur's Vaccine Discovery 13:47
    • Motivation to Discover a Way to Immunize People Against Disease
    • Cholera Bacteria
  • Vaccine Explanation 16:42
    • Inactive Versions of the Virus are Generated in a Culture
    • Antigens Injected Into the Person
    • Common Immunizations
    • Effectiveness
    • No Proof That Vaccines Cause Autism

Transcription: Biogenesis

Hi, welcome back to, this is the lesson on biogenesis.0000

To talk about biogenesis which mean life coming from life, that life makes life,0007

let us talk about spontaneous generation.0012

Hundreds of years ago, a belief known as spontaneous generation or abiogenesis was quite common.0014

When you put an A in front of a word like biogenesis, it means not that.0021

Like when you say atypical or asexual, not typical not sexual.0025

Abiogenesis means life is not coming from life.0030

Life is just popping up from out of nothing.0035

We know that cells make cells which make cells, and so on.0038

If you go back to the 1300’s, 1400’s, 1500’s, this was quite common.0044

I have this mouse here because people thought like, if you went to a place where there is like a barn 0051

and it would rain out, they thought that when the rain hit the hay, mice would come out of it.0059

I do not mean that just, that mice were hiding. I mean that mice were born out of it, that hay gives rise to mice when it rains.0067

What probably happen was, when it rained, the mice went to it for shelter to get out of the rain.0077

That is why they saw the mice are on the hay.0083

But people were not using scientific method to disprove that, it was just kind of word of mouth thing.0086

Like someone had an idea like that is how that happens, they would tell someone else, 0091

it would just kind of get passed around, that is pseudoscience.0096

This was the belief that life could consistently rise from non-living matter.0100

Pseudoscience is false, it is not true, it is not substantiated on actual research, where you have control of the variables.0104

Another belief was that, if you put raw meat outside, maggots would come out of it.0115

Possibly something in the air, some kind of a life force would enter the raw meat and cause maggots to be born.0122

It did not strike them that you would need adult flies to actually land on the meat and lay their little eggs that hatch into maggots.0130

They grow up into more adult flies.0140

This was just something that was a common belief until the scientific revolution.0144

From the start of the scientific revolution, just after the renaissance and that spurred a lot of it more intellectual thinking, 0150

you finally get into the 1600’s where there were a lot of advances via the scientific method to disprove some of these things. 0159

A few individuals starting with the 1600’s disprove some of these ridiculous things.0168

A few individuals, starting with the 1600’s, sought to disprove this theory, Francesco Redi, Lazzaro Spallanzani, and Louis Pasteur.0174

The amazing thing about these three gentlemen is they lived approximately hundred years apart.0178

Francesco Redi from the 1620’s to 1690’s.0183

Spallanzani from the 1720’s to 1790’s.0187

Louis Pasteur from the 1820’s to 1890’s.0190

Not exactly hundred years apart but pretty darn close.0194

It was this nice progression of getting closer and closer to disproving spontaneous generation.0199

Finally, it was Louis Pasteur that put the nail on the coffin, in terms of laying spontaneous generation to rest.0205

Let us start with Francesco Redi’s experiment, he was a 17th century Italian scientist living in the 1600’s.0214

Interesting thing about him, a crater on Mars is named after Redi.0220

Here he is with his nice little wig.0224

He wanted to debunk the theory that maggots, fly, larvae, emerge from rotting spoiling raw meat.0228

Here is what he did, he used a basic scientific method here.0235

Two jars, one covered with gauze and one not.0239

Here is no gauze and here is our meat at the bottom.0244

This one has a gauze, same kind of meat.0263

He left them out, what happened here is flies could come in and lay their little offspring.0279

Of course, maggots developed there.0294

Here, flies cannot get pass the gauze.0297

They desperately wanted to have this little food source down there and0303

lay their offspring down on this place where they can get some nice nutrition, but they could not.0308

You would think that Francesco Redi is like, done deal I disprove this.0313

This did convince enough people but not everyone.0319

They were still a lot of skeptics at this point because people would say things like,0323

Francesco you see in this particular beaker you have blocked out the vital force in the air.0328

There is a life force, in this particular beaker could not allow the life force to get to the meat.0337

Here you could have the air getting into here, allowing the meat to give rise to these.0343

People are going to be skeptical.0352

He did convince a lot of people but not clear enough.0356

This spontaneous generation idea kept on.0359

Great experiment really, in terms of having a control and having an experimental group0364

where you actually block out those flies from getting to there.0372

They have insisted that this one, the life force that people describe,0378

some kind of stuff was allowed to get into the meat but not here.0383

Somehow he blocked out the life force.0390

Next up, Lazzaro Spallanzani was 18th century Italian scientist, about a hundred years later.0394

Interesting fact about him, he died of bladder cancer.0401

His preserved bladder is still on display in an Italian town.0404

Not many people can claim that their bladder is on display for the public to see.0410

Spallanzani wanted to demonstrate that microbes could actually be in the air.0416

That it could be these living things that we just cannot see, but are in the air.0420

They could end up in broth, in spoiled broth.0426

Here is two containers, here we got chicken broth.0433

Normally it would be more of a brownish but we have got it with the yellow.0444

This one room temp, not boiled, and this one boiled.0453

Here we got bubbles, boiling hot.0467

This one of course is spoiled, it got nasty.0475

I do not have a brown marker to make it look nastier but let us do a sad face.0480

Because if you leave chicken broth or any food out, eventually it is going to spoil.0487

Bacteria are going to get into it, mold, fungal spores will get into it.0495

It will go bad because microorganisms will start to feed off of what is in there and they make offspring.0500

It gets to the point where it tastes and smells pretty nasty.0506

This one went bad, but when he boiled this one and put a cap on it, 0510

he killed 99, whatever, percent of the bacteria and this lasted a lot longer because of the boiling.0516

He thought that whatever microbes landed in there, whatever tiny little microscopic beings landed in there,0523

got to the point where he killed them all because of the boiling.0531

He had his critics as well, skeptics, people who said Lazzaro, 0536

when you boiled this you have made it so that you have destroyed the life force that could enter this and allow life to occur.0540

They did not think that there actually were living beings that could end up in the air, passed from person to person.0549

They understood that people got sick from each other, they saw there were something doing that.0557

People might have thought it was a spirit or a demon.0563

There were all kinds of theories that run substantiated and superstitious.0567

Once again, pseudoscience prevailed in a lot of people's minds.0572

Lazzaro did not completely disprove the theory beyond people's conceptions, what they thought was true.0576

Finally, along comes Louis Pasteur, 19th century French scientist, about a hundred years after Spallanzani.0588

Pasteurization is named after him.0595

The average store you go to, to get milk, milk is pasteurized.0599

Actually, alcohol beverages tend to be pasteurized as well.0605

Pasteurization is the act of like flash heating, bringing it to a very quick boiling level so that you kill 99.9% of germs.0609

Yes, eventually something like milk will spoil, even if you have milk that you never took the cap off in the refrigerator.0621

Eventually, like if you keep it in there for three months and then you take the cap off, it will probably smell bad,0629

that is why they do write some expiration date on it.0636

Once you take the cap off of pasteurized milk, 0640

you have now exposed it to new bacteria in the environment that you have opened up that carton in.0643

Pasteurization is really good at preventing people from getting unnecessary bacterial infections.0649

There is this newer trend I have heard where people go after unpasteurized milk.0656

It is not FDA recommended or approved. Food and Drug Administration, they do a lot of good in terms of monitoring food.0661

A lot of people are kind of anti-pasteurization now.0671

But, it saved a lot of lives.0674

These famous swan neck flask was a perfect way to disprove spontaneous generation.0677

Here is why he had a very skilled glass worker, glassmaker, make this interesting contraption.0681

This is an open end, this tube allows air to go in.0698

Here is your broth inside of here.0703

He made it where this was sterile broth, he knows for a fact there is nothing growing in it.0710

But attaches this part on the glass container so that air can be let in.0717

All of the sudden that you thought because you have prevented air from going in0724

because you have capped it off or you have gauze covering the opening.0730

No, air can freely flow through here.0736

As long as you do not tilt the flask, all the airborne bacteria they settle here,0738

the vast majority of bacteria do not have flagella, the majority of them.0746

Even if they had a tail that they could whip back and forth, they are not going to be able to climb all the way up here.0751

Right in here, probably it ends up pretty dirty after a while.0758

You do not want to take a drink of the flask from there.0762

Yes, he had another flask that if he tilted it over and allowed broth to come into here and let it comeback, 0765

that one is going to spoil because you are getting bacteria microbes from this area into the sterile fluid or sterile broth.0773

He showed that it is all good, it did not spoil because I have not allowed microbes from the environment to get into there.0782

This was part of his germ theory that there actually are these microscopic beings, 0791

bacteria, fungi, viruses, that cause people to get sick.0800

They cause these illnesses.0805

If we just can find a way to defeat the germ, you would not get sick.0807

This led the way to vaccinations or immunizations.0812

A vaccine is definitely something that he was responsible for making, a common practice today.0818

Pasteur’s vaccine discovery, Pasteur was a skilled microbiologist, love looking in microscopes, 0828

love figuring out what are these tiny little beings that are causing illnesses.0835

Three of his children died of typhoid fever.0840

Typhoid, you actually typically get it from fecal contamination, 0843

from bacteria that was in the person's body and feces coming out of them, ending up in water or the food supply.0849

You can imagine it back in the 1800’s, there really was not as much food regulation and sanitary restrictions as there are today.0857

Unfortunately, he saw three of his children die from this typhoid infection.0865

You got to think that, that spurred him into a passionate drive to discover a way to immunize people against diseases.0871

He realized that in this experiment he was doing with chickens, 0878

he was studying how cholera, a certain kind of bacterial infection, kills chickens.0881

Yes, he would actually inject the cholera in chickens, they consistently died.0888

In a kind of accidental way, he ended up getting a weakened version of the bacteria.0894

Just to see what would happen, he actually injected the weakened bacteria, the cholera bacteria, into the chickens.0900

They did not die, they did not get sick.0908

What he had done is, by exposing the chickens' immune system to this weakened cholera,0910

you are giving the tools for immunity to this chicken’s immune system, to the white blood cells.0918

The white blood cells see that, here are these proteins, these little things on the surface of the bacterial cells, 0924

we are going to make antibodies to those.0932

That is the raw material to stopping an infection from taking over and making someone or an animal like a chicken sick.0934

By injecting the weakened cholera into the chicken, he then subsequently found out that,0944

if he injected the active terrible cholera to the chicken, they did not die, they did not get sick.0950

By giving them the weakened cholera, he had in a sense vaccinated the chickens against that disease.0959

Later applied this knowledge to anthrax and rabies, other infections, measles arthrosis is another terrible bacterium.0967

This is actually cholera, this is cholera bacteria being grown in a petri dish.0978

The amazing thing is each one of these tiny little colonies, over a million bacteria.0984

There is a lot of bacterial cells on this, you do not want to get them too close to your face because it could definitely enter your body.0992

Some vaccine explanation for you.1004

Inactive versions of the virus or toxin are generated in a culture.1006

You can vaccinate somebody against viral infections or bacterial infections.1012

So that the virus, it would be, you can call it dead version of the virus meaning you got the viral envelope, 1017

the outer casing of the protein but it is not going to actively infect your cells and actually give you the viral infection.1026

That toxin from the bacteria is enough for your immune system to identify this is the bad stuff, 1034

this is a foreign body, let us figure out what this is and retain a memory for how to defeat it later on.1041

That is what your immune system does.1047

The reason why I said dead virus in the vaccine is because viruses are technically not alive, according to the definition of life.1049

More about that, when you see the virus lesson.1058

You generate them in a culture, antigens will be on the surface.1063

Whether we are talking about, let us say a virus that is shaped like this.1068

They look like spikes on the surface, these are protenacious projections.1072

These things are called antigens and they have a certain shape or certain confirmation, based on the virus.1079

Same thing with a bacterium which should be much larger than a virus.1087

They are tiny little proteins that project through the cell wall.1090

Every bacterium, every species of bacteria has slightly different version of these.1097

You can even get different strains of bacterial infections that have slight mutations1102

that cause slight different versions of those proteins.1109

Antigens, sometimes it is the casing itself or just toxins that come from this particular bacterium.1111

Those are injected into the person, that is the vaccination itself.1120

What happens is the moment those end up in your bloodstream, usually being here, 1124

the person's primary immune response, I’m going to highlight that.1131

The primary immune response, the first thing that immune system does, 1135

causes their B cells, a certain kind of white blood cell, to end up being exposed to those antigens.1139

They are presented to the B cells.1146

It is like, B cells this is something you need to take note of.1149

The B cells notice them and they produce antibodies.1152

Antibodies, there is an antibody, the variable portion of an antibody that and that, gets varied based on the shape of an antigen.1157

If an antigen, the surface of it is like this, then the antibody surface will match it, in terms of the shape.1169

And that allows antibodies to latch on to a virus or bacterium, the next time it is introduced.1179

The primary immune response definitely a significant response, 1187

based on presenting these antigens to B cells and producing antibodies that match the antigens.1192

You have these memory cells in your immune system that retain a memory of how to make those antibodies in the future.1198

These memory B cells will allow the body to have a secondary immune response, if ever exposed to the antigen again.1206

There are these graphs that show over time like, on the Y axis is the, let us call it intensity of immune response.1215

Meaning like, how many B cells get activated, how many antibodies get activated?1235

Here is time on the X axis.1243

When you are first injected with that vaccination, this is what happens, that is your primary immune response, 1246

the one with a little circle that stands for primary.1257

The second time you are introduced like, when you actually could have gotten sick meaning,1260

let us say you are injected for your primary immune response with a flu vaccine, a flu shot.1265

About two months later, someone with a flu comes up to you and coughs.1273

There are little flu viruses, eggs out of their mouth, you inhale them.1280

This is what happens.1284

Not only is the onset faster, you can see that like here is a gradual increase of immune response.1289

The onset is much faster and much harder, much more intense, this is that secondary immune response.1295

This is how vaccines work that, the second time your body is exposed to it, even the third time,1303

it could have this really intense response.1310

Thanks to those memory cells which retain a memory of how to make those antibodies1312

that match an antigen that they already have been exposed to.1317

A little bit more about vaccines, some common immunizations or vaccines that are given.1322

DPT this stands for diphtheria, pertussis, and tetanus.1326

These are all bacterial infections.1362

Diphtheria is an upper respiratory infection that can be fatal.1365

Pertussis is whooping cough, it is a pain in the butt to get, that has a very peculiar sound that is why it is nicknamed whopping cough.1369

Tetanus, these bacteria can get in the way of your skeletal muscle movement.1379

It can cause like just complete locking of your muscles, to the point where it can kill you.1384

It causes lockjaw among other, prolonged muscle contractions that you just you cannot help.1391

It is the bacteria it is causing that problem .1398

This DPT immunization or vaccination is very common to be given to babies born in first world countries.1401

That saved a lot of lives, it would be very terrible to get sick with those things.1409

Polio, this virus that caused Franklin D. Roosevelt to have some inability, physically, he was in a wheelchair a lot of the time.1413

MMR, measles, mumps, and rubella, these you do not want to get either.1426

That is another common MMR vaccines given to infants.1442

Varicella, this causes chicken pox.1445

Varicella zoster is something that I got sick with when I was young.1450

Back when I was a kid, the chicken pox vaccine was not widely distributed.1456

It is still being made and discovered.1461

Kids these days, actually I ask a class of students not long ago, how many of you have had chicken pox?1464

They are all about 14 to 15, none of them have because they all got vaccinated.1470

When I asked that question 8 years ago, almost half of them have it.1475

We are getting to the point where, now people do not have to worry about getting chicken pox.1480

HBV, this has to do with the hepatitis B vaccine.1484

Hepatitis is definitely a terrible liver disease, you rather not get it.1488

HPV, human papilloma virus, this causes genital warts.1495

Not only as genital warts, something you do not want to get as a sexually transmitted disease.1504

Genital warts, the HPV, this virus, it is been showed that has links to getting certain cancers,1511

cervical cancer and even cancers in males as well.1518

You rather not get this, not only is it unattractive and terrible to get, but the risk for cancer goes up.1522

Meningitis, it can be bacterial, viral, or fungal.1528

There are vaccinations for common forms of meningitis.1534

This is an infection of the meninges tha can be fatal.1537

These things all very common as vaccinations and it saved lives, it is a good thing.1540

Sometimes the effectiveness of vaccines only last several years and a booster maybe required.1548

I actually was vaccinated against meningitis a little over 10 years ago, before I went to college.1554

It is recommended that after about 10 years, you get another booster shot.1561

Supposedly, the effectiveness of how well your memory cells can retain that memory of making those antibodies, it kind of lessens a bit.1567

Getting a little booster is reminding your immune system, here is how to make these antibodies.1576

I should get another meningitis booster.1582

Meningitis is actually transmittable through saliva.1586

Something you have to be careful about.1589

By the way, there is no proof that vaccines cause autism.1591

This was something that was perpetuated through the media for a while, a few years ago.1596

The individual who actually released that study, 1604

it has been shown now that the original study that reported has falsified data.1608

Whoever he was, he made up a data that showed this correlation between autism in young children in them getting vaccinations.1613

There is no legitimacy to that.1622

Ask a doctor about vaccinations, they will tell you so much good they have done, millions of lives had been saved.1625

It is a way for your child to not get sick with unnecessary illnesses.1632

It is part of living in a modern day society and one of the benefits that medicine can give us.1638

Thanks for watching