100 Greatest Discoveries (2004) s01e02 Episode Script
Biology
An empire billions of years in the making A carnival of natural wonders Societies of cells Simple and complex All connected by an astonishing web of miraculous processes and global ecological systems A web of life These are the greatest discoveries in the history of biology In the early sixteenth hundreds, basic microscopes were used throughout Europe.
General scientist were held spell bang by their ability to enlarge the universe of the very small Then in 1665, an English scientist named Robert hook observed the tiny boxed in the sliver crock and called them cells.
Because they reminded him of the small room lived in by monks.
Hook's observation set the stage for our first great discovery.
Antoine Leeuwenhoek was a Dutch merchant fascinated with science Upon learning about hook's microscope, he decided to build one for himself Doc.
Gaul To find out what happened next, I paved a visit to Joseph Gaul A cell biologist at Carnegie institution in Baltimore Maryland Antoine Leeuwenhoek, What did he discover Leeuwenhoek discovered quite a few things.
But what is his most famous for are discovering protozoa That's small single cell animals living in pond water How did he do that He did use a microscope of his own construction Then would you like to see Oh yes.
You have a Leeuwenhoek microscope Not original.
I have a replica of Leeuwenhoek microscope It consists of two brass plates with a small piece of glass which at the lens And when you use this, it's to put the specimen on the pin here And then you hold your eye up very close to lens on this side And when you do that, you can see the point of the pin Would you like to take a look at Oh yeah It's kind of heavy Cause it 's brass, it's brass In 1675, then Leeuwenhoek was using his microscope to examine a bit of water When he observed something extraordinary A world full of creatures that no human would ever seen.
Microorganisms So with this, with all due respect, primitive gismo, yes.
He discovered single cell animals.
We take for granted yes But he is most famous for are discovering protozoa, bacteria and sperm.
This thing is brilliant It's got mechanical stage, it's got focusing device It got all over the things that you need to look at the specimen And it works The day they know they were seeing.
Do you what I mean like did they understand Well I doubt that they really understood what they were seeing in the modern sense But they were impressed that all the little things that were alive in water And people had no idea that water was teeming with organisms I guessed I just had no idea the thing was this small and delicate and frankly, so elegant Because it's upon your hand And what you see on the tip that pin changes the world.
It does, indeed It was an enlargement of our understanding of nature, nature than natural world That, that the world out there was not just dead things, but it was teeming with life Our next great discovery occurred in 1831.
English naturalist Robert brown was studying the different types of plant species he collected during a voyage to Australia Brown has an exquisite eye for detail The cells of the plant were of particular interested in him.
On examine under the microscope, he saw something intriguing In each cell, a similar structure, circular, opaque He called it the nucleus Upon learning of brown's observations German physiologist Theodor Schwann began looking for a similar structure in the cells of tadpoles.
And he found it.
Each in every cell of the tadpole has nucleus as well It was a revolutionary breakthrough.
Here was evidence that all life was connected.
In this book, Schwann describes every cell type from all sorts of organisms And identified them by the fact that they have a nucleus in them How would you say the discovery of nucleus was a great discovery The realization that there was a union structure to all organisms This was a union structure not only in plant but in animals So united both plant and animals kingdom into something that had similarities to each other More than a century after the discovery of the cell nucleus.
It was believed that there are two fundamental types of life on earth Bacteria and everything else Bacteria was classified prokaryote These were simple, single cell organism with their DNA contained not within a nucleus but by the cell wall.
All other life form were classified as eucaryon Their cells carried their DNA enclosed within the nucleus But this simple classification system was in for a shock In 1977, biologist Carl Woese was studying the genetic make-up of a methane-producing microbe When he realized it was different from any known bacteria.
Its cell wall was unique.
It produced unusual enzymes And its genetic sequence was unlike anything he'd ever seen.
It came soon apparent under within the microscope an hour That there was something a third thing at there This was the moment of discovery Carl Woese had found a third form of life A group of single cell organism that he called archaea We used to think that there are two primary kingdoms on this earth Now we know there are three That was the shift, the shift Because all of the microbiology have been structured on the idea that all bacteria are fundamentally the same not in all details but in their essence, their ancestry and their basic cell organization here are something that every microbiologist and biologist firmly believed in and it wasn't true so, it does make you smile.
Yeah, look I found what he found was a life form able to live anywhere on the planet including the most extreme environments.
Some archaea even call this home.
Hydrothermal events on the ocean floor Temperature here fluctuated wildly within just a few inches.
Going from freezing to a scorching 760 degrees Fahrenheit Archaea have also been found living miles inside the earth Thriving in lakes of acid even iron minerals dissolve Today, some biologist believe that archaea are the common ancestor from which you carried yourself off And that includes you and me For Carl woese, the discovery of archaea remains a sweet memory.
It was picked up one published by the New York time first And other newspaper and TV came in And I could remember I walking out my house when I say, When all this have seen, tonight, the world belongs to you.
Our next great discovery sought to answer the question at the heart of biology How cells form new life In the course of human events This is all pretty recent.
Right Yes.
We found nucleus, the cells around nucleus.
Animals and plants all have cells Yes And what happened next After a gap of some 30 years or so, people began to see cells dividing.
Cell division is the process that the cell of plant or animal go through to duplicate itself Well scientists had known about the process for decades German zoologist Walter Fleming was the first to describe and to publish his findings.
And his book was published in 1881 This book is momentous and extremely important in cell biology Because Fleming described cell division in a way which would be acceptable in modern journal Fleming observed the process of cell division in great detail.
With the help of a powerful new microscope and a new dyed stinging techniques With these innovations, he was able to identified structure that later was named chromosomes.
And then his great discovery During cell division, the chromosomes undergo dynamic change.
They divide into two identical parts.
One for each daughter cell.
Fleming called this process mitosis So, that's the whole process of mitosis as he described it in 1881 And the tadpole tail yes, the tadpole tail yes And he knew to go to the tail because the tail is growing and the back of tadpole is going on Exactly He knew that if you want to see the cell division in details, in details I am sorry for the pun.
Oh.
I love the pun cookie for the pun.
Then, that's was one of the places to look.
The splitting of the chromosomes during mitosis was a breakthrough discovery.
It opened the door for scientists to begin understanding How one cell can turn into a complex organism, made of many interacting cells.
Around the time that Walter Fleming was studying the cell division process.
Biologists already knew that fertilization resulted from the union of two sex cells sperm and egg what they didn't know was why this was the only type of cells in body capable of reproducing new life what made them different The first answer was provided in 1883 by Belgian zoologist Edward van Beneden Van beneden was studying a species of roundworm And then discovered that all of its cells contain four chromosomes The only exceptions were the roundworm's sex cells.
The male's sperm and the female's egg, these cells had only two chromosomes.
Then beneden observed that once two of the sex cells came together A full set of four chromosome appeared in the fertilized egg But just why the sex cells had only the half number of the chromosomes compared to the all the other cells was still a mystery.
Then in 1887, German biologist August Weismann entered the picture.
He knew about the work of van beneden who have shown that the sperm and egg bring the an equal number of chromosomes But van beneden's work had not really worked out the details of how the chromosomes were reduced in number.
He thought he thought them go in half and he thought them recombine He thought the sperm and egg brought in half number of chromosomes than the body cells But he didn't really know how they got rid of the half.
They got rid of So Weismann discussed how this might happened from a theoretical standpoint And he said, well, what you could have would be that either one of the chromosome was just split in half and half would go off one way and half would go another way.
Or, you could have more complicated, that the chromosome could paired and then, instead of splitting, they just separated again After years of studying the behavior chromosomes Weismann determined that some point, a developing organism signals the sex cells To divide their number of chromosomes in half Weismann called this very special form of cell division meiosis I think they would look back and see this as the golden age of biology Because let's say 200 years between 1800-2000 We went from not knowing what distinguish the stone from a frog Ok.
And now we know the difference between the stone and the frog That's pretty good So that, in a real sense, we've answered the old philosophical question, what is life May be not to everybody's satisfaction but we are well on the way Our next great discovery answered another question about the biology of life.
In the late 19 century, Biologists knew that during the formation of embryo, the cells of most organisms became differentiated That is they received their assignments for specific jobs in the adult organisms.
Arms, legs.
Eyes But when did this differentiation happened German biologist Hans Driesch was determined to find the answer.
In the lab experiment with sea urchin He observed that in the early stage of an embryo development.
Its cells are not yet differentiated They can still develop into all cell types Today, scientists called cells that can develop to all or many types, stem cells.
.
- Hi bill.
- Hi To find out more, I paved a visit to Helen Blau Who was directing stem cell research at Stanford University's genetic pharmacology lab Everybody is talking about stem cells Cells started out their fertilized and they stated to divide But they still haven't sort of divide into what I would think liver cell, fingernail cell, eye cell, right That's right And what do you call that So that points their totipotent cell They have a lot of plasticity and they can give rise to all cells in the organism.
And then something changes, we don't know what that something is.
But those cells are now destined to make different kind of tissues And that's why we have organs such as the heart, and the liver, and the spleen in an adult So then the question is how yearn reversible are these decisions So, I wanted to challenge the idea that the cells were yearn reversible determined That once the cell became liver that was it.
And so, we showed that they were not yearn reversible determined And that by perturbing their environment inside the cell You could activate genes that were usually never used.
That demonstrated the certain kind of plasticity And this kind of plasticity that people are trying to unleash in stem cells So, understanding the mechanism under minus may allowed us to use the fundamental principles we discovered in treating disease What's recreating the cells, what's getting them to fuse And what's getting them to reprogrammed.
So it's even more efficient.
We might unleash that and what called regenerate medicine We are finding that cells have more potential than we thought before.
So that a blood cell, stem cell, not only makes the blood.
But those cells came travel elsewhere through the circulation to aid and repair damage in tissues such as muscles, tissues as the brain, also liver.
And that's v been shown in several labs now.
Sound like star track or something, do you remind.
Dr.
Maicao the guy in 15 seconds and later it was Ok.
Well that was quiet like that.
yes, we got To gain a better understanding of the new technologies that Helen Blau was using to uncover the potential of stem cells.
She showed me an experiment being conducted with genetically-altered mice.
So, that is one unusual mouse, certainly is It has green fluorescence protein in all of the cells of its body.
Because we have been able to introduce the jellyfish's GFP gene into these mice Now, their tissues are glowing, particularly in the ears, the eyes, the tail.
It's But all the tissues are, are green It's unable to take cells that glow and put them into another mouse And see what tissue it would participated.
So, in the way you can follow what stem cells can do It's a marker, it's a marker, yes Just all you need is ultraviolet That's right and it didn't exist before And because of that we now can follow the trace of the cells Where the cells go, what they become And in a way it wasn't previously possible It's fantastic In the 1930, German biologist Hans Krebs, the son of a Jewish physician, was forced to flee Nazi Germany By 1937, he was doing research in the University of Cambridge in England Determined to unraveled the mystery behind the central biology process How did the cells in our body convert food into energy It's our next great discovery.
To investigate this process Hans Krebs broke open a group of cells by grinding a sample of animal tissue He collected the liquid from the broken cells And put the content through a serious of chemical reactions And measured the results.
Slowly, a pattern began to emerge.
A pattern that led to a remarkable discovery From his measurements, Krebs determined that sugar molecules from digested food Go through a cycle of a various chemical reactions inside the cell The cycle result in the production of the energy rich molecules ATP This molecule provides us with the energy we need to make us go And the cycle of chemical reactions is known as the Krebs' cycle It was a milestone discovery in the development of biochemistry.
The Krebs' cycle opened the door to a deep understanding of how cells function in the human body Just like our next great discovery.
In the mid nineteenth century, scientist using powerful microscopes, found something never seen before.
A mysterious structure lurking inside nearly all the types of cells.
It was equipped with two membranes and had the ability to change the shape.
Over the next hundreds years, several biologists combined to uncover the secrets of this biological wonder.
They called this structures mitochondrion Among the scientists involved the first way of discovery about mitochondrion was Britton Chance His contribution included the invention of door waved linked spectral photometer A device that provided scientists with a clearer picture of how mitochondrion function Today, he is a professor of biophysics at the university of Pennsylvania I make a gadget, this gadget would look through the turbidity of these organelles Because they had membranes and they had cell walls And had things with scattered light near the hold of multiplies or you can see was a fuss Well, we made an instrument which got rid of the fuss And found two components that linked the mitochondrion to Hans Krebs' citric acid cycle So this sort of tied the whole things up and made links between enzyme action and the whole energy chain So it was together With the help of chance's invention scientists found the mitochondrion that provides the energy that enables us the cells to work and the body to function The mitochondrion hast to be a very efficient way of using the food stuff that the whole cells gathers And this is called the phenomena of respiratory control To a man, it means that he can exercise like hell you wants to, and all he has to do is stop to recoup in another word, he don't have to take a pill, he don't have to take an injection well, his mitochondrion will reconstitute the energy deficit having done that and go to sleep so, I think, especially in these days of Olympics sports where everybody pushing their ATP to the very limit it has a real significance Britton Chance appreciates that significance as a scientist and as an athlete In 1952, he won a gold medal as a member of us Olympic sailing team I think discovering the components, studying the mitochondrion and veval finding how they work Showing how important respiratory control was and how it works And of course, studying free radical generation which now is recognized as enough to dangerous but a signal process And that was sort off kicks me of the street now, I am working more on brain and cancer.
Because of the implications of mitochondrionology there At the end of the nineteenth century, one of the great puzzles challenging the scientists was how the billions of nerve cells that make up of the human nervous systems communicate with each other They knew that each nerve cell called the neuron carries electron impulses And many believed that the connection allowed the impulses to jump from on one neuron to another was electrical as well Until our next great discovery In the early nineteenth hundreds, British biologist Henry Dale was conducting a serious of lab experiments Studying the physiology of nerve impulses In one of his experiments, he injected adrenaline into a cat Expecting the animal's heart rate increase, but nothing happened.
Suddenly, Dale realized his mistake It was the same cat that he already given another drug to, one that slowed the heart rate With this mix-up Dale realized that he was under something If a drug could interrupt the nerve impulses that governing the beating of the heart.
Then the connection between neurons must be chemical, not electrical Dale turned his colleague, German biologist Auto Louie for help To test Dale's hypotheses, Louie conducted an experiment using two frogs.
Louie put the first frog in a saline solution And then he electronically stimulate its vagus nerve, the nerve that control its heart beat The frog's heart beat slowed Next Louie took some of the solution in applied to the heart of the second frog.
What happened next was extraordinary.
Without any electrical stimulation of its vagus nerve, The second heart slowed as well This was the moment of discovery Louie realized that the vagus nerve of the first frog has released chemical Which had directed the second frog's heart muscles to slow their contractions Here was proof that the transmission of impulses among nerve cells and then into the heart muscle was chemical Louise has discovered the existence of the first known nerve chemical Now are called neurotransmitter Today, we know there are many neurotransmitters in the human body And researchers are using this knowledge to learn more about how the brain works At the chemical messages at sense For example, low levels of serotonin have been connected with pression, alcoholism and anxiety this orders But is our next great discovery revealed that nervous system isn't the human body's only method of communication In 1903, two British physiologists William Bayliss and Ernest Starling were investigating the food digestion process From their studies, they determined that the body produced digested juices that helped break down food, once it moves from the stomach to the intestine But what caused the digested juice to flow To find out, Bayliss and Starling conducted an experiment.
They took a blood sample from a dog that had just eaten a meal Then injected the blood into a second dog, this one with the empty stomach Then something astonishing happened Without any food in his belly, the second dog began secreting digested juices from an organ called the pancreas How was this happened After more testing, Bayliss and Starling finally had their answers, When the food reaches its intestine, the intestine produces a chemical substance,which then carried the blood stream to the pancreas Here, it stimulates the pancreas to produce secretion that helps digest the food Bayliss and Starling called this chemical secretin The first they realized was a never before seen group of chemical substances.
They called this substances hormones Since Bayliss and Starling's discovery, more than 50 hormones have been identified Hormones that are produced by gland and tissues and carried in the blood stream as the human body needs them.
There are hormones which affect the body's growth, metabolism, heart rate and blood sugar.
They even help us prepare for reproduction Estrogen, for example, is one of several female hormones it helps prepare the room for the baby and the breasts for feeding So far, we've seen the discoveries that reveal the biology life on the microscopic level Our next great discoveries open our eyes to the biology of the macro Those system s on which all life on the planet depends The year is 1771; chemist Joseph Priestley conducted a serious of experiments.
To see what happened when he hit various substances in close jars and collected the gas coming off.
In one of his experiments, he put a litten candle in the jar but the flame quickly burned out.
In Priestley's words, the air inside the jar was injured.
Curious what affect this injured air might have on an living thing He put a mint leaf inside the jar and left there for ten days.
When Priestley checked back, incredibly, the leaf was still green Somehow the air inside the jar was fresh again, Priestley speculated that the mint leaf must be responsible for the transformation.
But.
How This question remained unanswered until a Dutch scientist named Jan Ingenhousz decided to duplicate Priestley's experiment.
Using plants, Ingenhousz witnessed the same beguiling phenomena After conducting a serious of more tests, Ingenhousz began to realize what was happening.
The ability of the plant to transform the air inside the jar only worked if the plant was exposed to the sunlight.
This was the breakthrough, Together, Prestley and Ingenhousz had discovered photosynthesis The biochemical process by which plants trap the energy of the sunlight and convert it into chemical energy.
Photosynthesis removes carbon dioxide from the atmosphere And replenished it with the gas on which our survival depends, oxygen.
The same gas that Joseph Priestley would discovered 3 years later in 1774 Our next great discovery has no discoverer in a classic sense.
Many took hand in expressing and shaping the idea over the several centuries It's the discovery of tropical diversity.
And today, it's fundamental to our understanding of the biological world and our dependence on it.
The term biodiversity refers to the variety of living things on earth and their interactions with the environment.
The tropical rainforests are the richest recourse of biodiversity on the planet In the 15th century, Italian explorer Amerigo Vespucci visited the tropics and wrote it in his journal What should I tell of the multitude of wild animals So many species could not invent in Noah's Ark Today, we continue to be odd by the biodiversity of the tropics An estimate 50 percent of all the species in the world inhabit tropical rainforests.
An area that occupies only 2 percent of the land on the earth's surface.
The Amazonian rainforest in brazil has nearly five hundred species of trees growing in an area of just two and half square miles.
Compared that to the total area of the unites state and Canada, which combine, have only about 700 species of trees.
But just why the discovery of tropical biodiversity consider so important Because not only did it enable scientists to better understand the natural systems at that work here But helped them began to harvest and extraordinary rearrange the sources which touch our life every day.
From the production of more food and better industrial products to the development of new medicines For example, many of the most promising anti-cancer drugs come from plants found in the world tropical rainforests.
But those benefits have come up a deep price Scientists estimate that loss of tropical biodiversity is happening at an alarming rate.
Millions of acres of habitats have been out countless species have gone distinct It's estimated that with the current rate of deforestation All tropical rainforests could disappear by the year 2030 That disappearance has far-reaching environmental implications Because as our next great discovery revealed all the earth biological systems and the community of life that depended on them are connected The dust ball of nineteen thirties After years of drought the once fertilized America mid-west became a waste land.
Without rain, farmers continued to plow and plant Hoping that the nutrient in the field would somehow be replenished.
But their efforts only made things worse.
The top soil turned to dust And the wind took its avenges For British ecologist Arthur Tensely, the dust ball was proof that scientists and the public in large Were too narrow when they are view of the physical and biological world They did not understand the dynamic of the environment as a whole.
A perspective that helped to explain the cause and effect of events like the dust ball He advocated a new concept, what he called the ecosystem The world has simplicity to its understandable by the ordinary person that can be applied effectively Also has a scientific significance in the apt it brings together ideas form variety of sciences To understand the impact of Tinsley's idea, I paved a visit to Frank Golley state botanical garden in Athens Georgia Why was this a revolutionary shift in thinking At that time, ecological work was a strongly involved with the description in the nature And the system approach, you are actually is going further your experimenting You are looking for patterns That are persistent across a variety of locations and species And then you make statement about the way they perform that can be tested Its moves ecology into the same value as physics and chemistry and molecule biology So, Tensely took the word system and applied it to ecological studies.
He tried to convey the idea that ecology is part of a hierarchy physical system at the universe at one extreme To the atom and the other So, that's someone may be the solar system Yes - And down blow that would be ecosystems, - Yes Back here is something I want to show you, the quantity of silt that you see in the river right now.
Is due to the erosion of the farmland that upstream This is a opportunity to see what we could say is a ecosystem defined physically.
Bill, right here, in front of us.
So, this is a flood plain that's right As we see the water from the Oconee river.
Periodically we get enormous rainfall and the river floods And would then, send the water into this sort of area Would might be we might be stemming just deep in water during a flood.
Presumable at one time, it was a forest See the reminisce of the trees.
But because the floodingand, persistence of flooding, the tree's roots were unable to respire and the trees died you can see if you look yourself around here how beautiful before they recovering forest and its shape We've study that in great detail, using an ecosystem approach So, we are able to talk about the how to rebuild ecological systems here in this region But manipulating the very species and the environment to speed up the process to get the .
.
we want to amply size and to do it at the blast cause, And that's a very positive step Cause we can rebuild nature to meet certain human needs And so it has functions and maintains itself honestly own under solar power.
Solar power yes Under solar power Which is driving all the cycle s and everything else.
Our journey through the greatest discoveries in the history of biology has revealed an amazing diversity of life on earth.
And it has given us an insight at that how life works From a life cycle of a smaller cell, to the system that governs the physical environment of our entire planet But there is one insight that .
.
all above others is this.
The search for more discoveries about life is never ending.
That journey goes on forever
General scientist were held spell bang by their ability to enlarge the universe of the very small Then in 1665, an English scientist named Robert hook observed the tiny boxed in the sliver crock and called them cells.
Because they reminded him of the small room lived in by monks.
Hook's observation set the stage for our first great discovery.
Antoine Leeuwenhoek was a Dutch merchant fascinated with science Upon learning about hook's microscope, he decided to build one for himself Doc.
Gaul To find out what happened next, I paved a visit to Joseph Gaul A cell biologist at Carnegie institution in Baltimore Maryland Antoine Leeuwenhoek, What did he discover Leeuwenhoek discovered quite a few things.
But what is his most famous for are discovering protozoa That's small single cell animals living in pond water How did he do that He did use a microscope of his own construction Then would you like to see Oh yes.
You have a Leeuwenhoek microscope Not original.
I have a replica of Leeuwenhoek microscope It consists of two brass plates with a small piece of glass which at the lens And when you use this, it's to put the specimen on the pin here And then you hold your eye up very close to lens on this side And when you do that, you can see the point of the pin Would you like to take a look at Oh yeah It's kind of heavy Cause it 's brass, it's brass In 1675, then Leeuwenhoek was using his microscope to examine a bit of water When he observed something extraordinary A world full of creatures that no human would ever seen.
Microorganisms So with this, with all due respect, primitive gismo, yes.
He discovered single cell animals.
We take for granted yes But he is most famous for are discovering protozoa, bacteria and sperm.
This thing is brilliant It's got mechanical stage, it's got focusing device It got all over the things that you need to look at the specimen And it works The day they know they were seeing.
Do you what I mean like did they understand Well I doubt that they really understood what they were seeing in the modern sense But they were impressed that all the little things that were alive in water And people had no idea that water was teeming with organisms I guessed I just had no idea the thing was this small and delicate and frankly, so elegant Because it's upon your hand And what you see on the tip that pin changes the world.
It does, indeed It was an enlargement of our understanding of nature, nature than natural world That, that the world out there was not just dead things, but it was teeming with life Our next great discovery occurred in 1831.
English naturalist Robert brown was studying the different types of plant species he collected during a voyage to Australia Brown has an exquisite eye for detail The cells of the plant were of particular interested in him.
On examine under the microscope, he saw something intriguing In each cell, a similar structure, circular, opaque He called it the nucleus Upon learning of brown's observations German physiologist Theodor Schwann began looking for a similar structure in the cells of tadpoles.
And he found it.
Each in every cell of the tadpole has nucleus as well It was a revolutionary breakthrough.
Here was evidence that all life was connected.
In this book, Schwann describes every cell type from all sorts of organisms And identified them by the fact that they have a nucleus in them How would you say the discovery of nucleus was a great discovery The realization that there was a union structure to all organisms This was a union structure not only in plant but in animals So united both plant and animals kingdom into something that had similarities to each other More than a century after the discovery of the cell nucleus.
It was believed that there are two fundamental types of life on earth Bacteria and everything else Bacteria was classified prokaryote These were simple, single cell organism with their DNA contained not within a nucleus but by the cell wall.
All other life form were classified as eucaryon Their cells carried their DNA enclosed within the nucleus But this simple classification system was in for a shock In 1977, biologist Carl Woese was studying the genetic make-up of a methane-producing microbe When he realized it was different from any known bacteria.
Its cell wall was unique.
It produced unusual enzymes And its genetic sequence was unlike anything he'd ever seen.
It came soon apparent under within the microscope an hour That there was something a third thing at there This was the moment of discovery Carl Woese had found a third form of life A group of single cell organism that he called archaea We used to think that there are two primary kingdoms on this earth Now we know there are three That was the shift, the shift Because all of the microbiology have been structured on the idea that all bacteria are fundamentally the same not in all details but in their essence, their ancestry and their basic cell organization here are something that every microbiologist and biologist firmly believed in and it wasn't true so, it does make you smile.
Yeah, look I found what he found was a life form able to live anywhere on the planet including the most extreme environments.
Some archaea even call this home.
Hydrothermal events on the ocean floor Temperature here fluctuated wildly within just a few inches.
Going from freezing to a scorching 760 degrees Fahrenheit Archaea have also been found living miles inside the earth Thriving in lakes of acid even iron minerals dissolve Today, some biologist believe that archaea are the common ancestor from which you carried yourself off And that includes you and me For Carl woese, the discovery of archaea remains a sweet memory.
It was picked up one published by the New York time first And other newspaper and TV came in And I could remember I walking out my house when I say, When all this have seen, tonight, the world belongs to you.
Our next great discovery sought to answer the question at the heart of biology How cells form new life In the course of human events This is all pretty recent.
Right Yes.
We found nucleus, the cells around nucleus.
Animals and plants all have cells Yes And what happened next After a gap of some 30 years or so, people began to see cells dividing.
Cell division is the process that the cell of plant or animal go through to duplicate itself Well scientists had known about the process for decades German zoologist Walter Fleming was the first to describe and to publish his findings.
And his book was published in 1881 This book is momentous and extremely important in cell biology Because Fleming described cell division in a way which would be acceptable in modern journal Fleming observed the process of cell division in great detail.
With the help of a powerful new microscope and a new dyed stinging techniques With these innovations, he was able to identified structure that later was named chromosomes.
And then his great discovery During cell division, the chromosomes undergo dynamic change.
They divide into two identical parts.
One for each daughter cell.
Fleming called this process mitosis So, that's the whole process of mitosis as he described it in 1881 And the tadpole tail yes, the tadpole tail yes And he knew to go to the tail because the tail is growing and the back of tadpole is going on Exactly He knew that if you want to see the cell division in details, in details I am sorry for the pun.
Oh.
I love the pun cookie for the pun.
Then, that's was one of the places to look.
The splitting of the chromosomes during mitosis was a breakthrough discovery.
It opened the door for scientists to begin understanding How one cell can turn into a complex organism, made of many interacting cells.
Around the time that Walter Fleming was studying the cell division process.
Biologists already knew that fertilization resulted from the union of two sex cells sperm and egg what they didn't know was why this was the only type of cells in body capable of reproducing new life what made them different The first answer was provided in 1883 by Belgian zoologist Edward van Beneden Van beneden was studying a species of roundworm And then discovered that all of its cells contain four chromosomes The only exceptions were the roundworm's sex cells.
The male's sperm and the female's egg, these cells had only two chromosomes.
Then beneden observed that once two of the sex cells came together A full set of four chromosome appeared in the fertilized egg But just why the sex cells had only the half number of the chromosomes compared to the all the other cells was still a mystery.
Then in 1887, German biologist August Weismann entered the picture.
He knew about the work of van beneden who have shown that the sperm and egg bring the an equal number of chromosomes But van beneden's work had not really worked out the details of how the chromosomes were reduced in number.
He thought he thought them go in half and he thought them recombine He thought the sperm and egg brought in half number of chromosomes than the body cells But he didn't really know how they got rid of the half.
They got rid of So Weismann discussed how this might happened from a theoretical standpoint And he said, well, what you could have would be that either one of the chromosome was just split in half and half would go off one way and half would go another way.
Or, you could have more complicated, that the chromosome could paired and then, instead of splitting, they just separated again After years of studying the behavior chromosomes Weismann determined that some point, a developing organism signals the sex cells To divide their number of chromosomes in half Weismann called this very special form of cell division meiosis I think they would look back and see this as the golden age of biology Because let's say 200 years between 1800-2000 We went from not knowing what distinguish the stone from a frog Ok.
And now we know the difference between the stone and the frog That's pretty good So that, in a real sense, we've answered the old philosophical question, what is life May be not to everybody's satisfaction but we are well on the way Our next great discovery answered another question about the biology of life.
In the late 19 century, Biologists knew that during the formation of embryo, the cells of most organisms became differentiated That is they received their assignments for specific jobs in the adult organisms.
Arms, legs.
Eyes But when did this differentiation happened German biologist Hans Driesch was determined to find the answer.
In the lab experiment with sea urchin He observed that in the early stage of an embryo development.
Its cells are not yet differentiated They can still develop into all cell types Today, scientists called cells that can develop to all or many types, stem cells.
.
- Hi bill.
- Hi To find out more, I paved a visit to Helen Blau Who was directing stem cell research at Stanford University's genetic pharmacology lab Everybody is talking about stem cells Cells started out their fertilized and they stated to divide But they still haven't sort of divide into what I would think liver cell, fingernail cell, eye cell, right That's right And what do you call that So that points their totipotent cell They have a lot of plasticity and they can give rise to all cells in the organism.
And then something changes, we don't know what that something is.
But those cells are now destined to make different kind of tissues And that's why we have organs such as the heart, and the liver, and the spleen in an adult So then the question is how yearn reversible are these decisions So, I wanted to challenge the idea that the cells were yearn reversible determined That once the cell became liver that was it.
And so, we showed that they were not yearn reversible determined And that by perturbing their environment inside the cell You could activate genes that were usually never used.
That demonstrated the certain kind of plasticity And this kind of plasticity that people are trying to unleash in stem cells So, understanding the mechanism under minus may allowed us to use the fundamental principles we discovered in treating disease What's recreating the cells, what's getting them to fuse And what's getting them to reprogrammed.
So it's even more efficient.
We might unleash that and what called regenerate medicine We are finding that cells have more potential than we thought before.
So that a blood cell, stem cell, not only makes the blood.
But those cells came travel elsewhere through the circulation to aid and repair damage in tissues such as muscles, tissues as the brain, also liver.
And that's v been shown in several labs now.
Sound like star track or something, do you remind.
Dr.
Maicao the guy in 15 seconds and later it was Ok.
Well that was quiet like that.
yes, we got To gain a better understanding of the new technologies that Helen Blau was using to uncover the potential of stem cells.
She showed me an experiment being conducted with genetically-altered mice.
So, that is one unusual mouse, certainly is It has green fluorescence protein in all of the cells of its body.
Because we have been able to introduce the jellyfish's GFP gene into these mice Now, their tissues are glowing, particularly in the ears, the eyes, the tail.
It's But all the tissues are, are green It's unable to take cells that glow and put them into another mouse And see what tissue it would participated.
So, in the way you can follow what stem cells can do It's a marker, it's a marker, yes Just all you need is ultraviolet That's right and it didn't exist before And because of that we now can follow the trace of the cells Where the cells go, what they become And in a way it wasn't previously possible It's fantastic In the 1930, German biologist Hans Krebs, the son of a Jewish physician, was forced to flee Nazi Germany By 1937, he was doing research in the University of Cambridge in England Determined to unraveled the mystery behind the central biology process How did the cells in our body convert food into energy It's our next great discovery.
To investigate this process Hans Krebs broke open a group of cells by grinding a sample of animal tissue He collected the liquid from the broken cells And put the content through a serious of chemical reactions And measured the results.
Slowly, a pattern began to emerge.
A pattern that led to a remarkable discovery From his measurements, Krebs determined that sugar molecules from digested food Go through a cycle of a various chemical reactions inside the cell The cycle result in the production of the energy rich molecules ATP This molecule provides us with the energy we need to make us go And the cycle of chemical reactions is known as the Krebs' cycle It was a milestone discovery in the development of biochemistry.
The Krebs' cycle opened the door to a deep understanding of how cells function in the human body Just like our next great discovery.
In the mid nineteenth century, scientist using powerful microscopes, found something never seen before.
A mysterious structure lurking inside nearly all the types of cells.
It was equipped with two membranes and had the ability to change the shape.
Over the next hundreds years, several biologists combined to uncover the secrets of this biological wonder.
They called this structures mitochondrion Among the scientists involved the first way of discovery about mitochondrion was Britton Chance His contribution included the invention of door waved linked spectral photometer A device that provided scientists with a clearer picture of how mitochondrion function Today, he is a professor of biophysics at the university of Pennsylvania I make a gadget, this gadget would look through the turbidity of these organelles Because they had membranes and they had cell walls And had things with scattered light near the hold of multiplies or you can see was a fuss Well, we made an instrument which got rid of the fuss And found two components that linked the mitochondrion to Hans Krebs' citric acid cycle So this sort of tied the whole things up and made links between enzyme action and the whole energy chain So it was together With the help of chance's invention scientists found the mitochondrion that provides the energy that enables us the cells to work and the body to function The mitochondrion hast to be a very efficient way of using the food stuff that the whole cells gathers And this is called the phenomena of respiratory control To a man, it means that he can exercise like hell you wants to, and all he has to do is stop to recoup in another word, he don't have to take a pill, he don't have to take an injection well, his mitochondrion will reconstitute the energy deficit having done that and go to sleep so, I think, especially in these days of Olympics sports where everybody pushing their ATP to the very limit it has a real significance Britton Chance appreciates that significance as a scientist and as an athlete In 1952, he won a gold medal as a member of us Olympic sailing team I think discovering the components, studying the mitochondrion and veval finding how they work Showing how important respiratory control was and how it works And of course, studying free radical generation which now is recognized as enough to dangerous but a signal process And that was sort off kicks me of the street now, I am working more on brain and cancer.
Because of the implications of mitochondrionology there At the end of the nineteenth century, one of the great puzzles challenging the scientists was how the billions of nerve cells that make up of the human nervous systems communicate with each other They knew that each nerve cell called the neuron carries electron impulses And many believed that the connection allowed the impulses to jump from on one neuron to another was electrical as well Until our next great discovery In the early nineteenth hundreds, British biologist Henry Dale was conducting a serious of lab experiments Studying the physiology of nerve impulses In one of his experiments, he injected adrenaline into a cat Expecting the animal's heart rate increase, but nothing happened.
Suddenly, Dale realized his mistake It was the same cat that he already given another drug to, one that slowed the heart rate With this mix-up Dale realized that he was under something If a drug could interrupt the nerve impulses that governing the beating of the heart.
Then the connection between neurons must be chemical, not electrical Dale turned his colleague, German biologist Auto Louie for help To test Dale's hypotheses, Louie conducted an experiment using two frogs.
Louie put the first frog in a saline solution And then he electronically stimulate its vagus nerve, the nerve that control its heart beat The frog's heart beat slowed Next Louie took some of the solution in applied to the heart of the second frog.
What happened next was extraordinary.
Without any electrical stimulation of its vagus nerve, The second heart slowed as well This was the moment of discovery Louie realized that the vagus nerve of the first frog has released chemical Which had directed the second frog's heart muscles to slow their contractions Here was proof that the transmission of impulses among nerve cells and then into the heart muscle was chemical Louise has discovered the existence of the first known nerve chemical Now are called neurotransmitter Today, we know there are many neurotransmitters in the human body And researchers are using this knowledge to learn more about how the brain works At the chemical messages at sense For example, low levels of serotonin have been connected with pression, alcoholism and anxiety this orders But is our next great discovery revealed that nervous system isn't the human body's only method of communication In 1903, two British physiologists William Bayliss and Ernest Starling were investigating the food digestion process From their studies, they determined that the body produced digested juices that helped break down food, once it moves from the stomach to the intestine But what caused the digested juice to flow To find out, Bayliss and Starling conducted an experiment.
They took a blood sample from a dog that had just eaten a meal Then injected the blood into a second dog, this one with the empty stomach Then something astonishing happened Without any food in his belly, the second dog began secreting digested juices from an organ called the pancreas How was this happened After more testing, Bayliss and Starling finally had their answers, When the food reaches its intestine, the intestine produces a chemical substance,which then carried the blood stream to the pancreas Here, it stimulates the pancreas to produce secretion that helps digest the food Bayliss and Starling called this chemical secretin The first they realized was a never before seen group of chemical substances.
They called this substances hormones Since Bayliss and Starling's discovery, more than 50 hormones have been identified Hormones that are produced by gland and tissues and carried in the blood stream as the human body needs them.
There are hormones which affect the body's growth, metabolism, heart rate and blood sugar.
They even help us prepare for reproduction Estrogen, for example, is one of several female hormones it helps prepare the room for the baby and the breasts for feeding So far, we've seen the discoveries that reveal the biology life on the microscopic level Our next great discoveries open our eyes to the biology of the macro Those system s on which all life on the planet depends The year is 1771; chemist Joseph Priestley conducted a serious of experiments.
To see what happened when he hit various substances in close jars and collected the gas coming off.
In one of his experiments, he put a litten candle in the jar but the flame quickly burned out.
In Priestley's words, the air inside the jar was injured.
Curious what affect this injured air might have on an living thing He put a mint leaf inside the jar and left there for ten days.
When Priestley checked back, incredibly, the leaf was still green Somehow the air inside the jar was fresh again, Priestley speculated that the mint leaf must be responsible for the transformation.
But.
How This question remained unanswered until a Dutch scientist named Jan Ingenhousz decided to duplicate Priestley's experiment.
Using plants, Ingenhousz witnessed the same beguiling phenomena After conducting a serious of more tests, Ingenhousz began to realize what was happening.
The ability of the plant to transform the air inside the jar only worked if the plant was exposed to the sunlight.
This was the breakthrough, Together, Prestley and Ingenhousz had discovered photosynthesis The biochemical process by which plants trap the energy of the sunlight and convert it into chemical energy.
Photosynthesis removes carbon dioxide from the atmosphere And replenished it with the gas on which our survival depends, oxygen.
The same gas that Joseph Priestley would discovered 3 years later in 1774 Our next great discovery has no discoverer in a classic sense.
Many took hand in expressing and shaping the idea over the several centuries It's the discovery of tropical diversity.
And today, it's fundamental to our understanding of the biological world and our dependence on it.
The term biodiversity refers to the variety of living things on earth and their interactions with the environment.
The tropical rainforests are the richest recourse of biodiversity on the planet In the 15th century, Italian explorer Amerigo Vespucci visited the tropics and wrote it in his journal What should I tell of the multitude of wild animals So many species could not invent in Noah's Ark Today, we continue to be odd by the biodiversity of the tropics An estimate 50 percent of all the species in the world inhabit tropical rainforests.
An area that occupies only 2 percent of the land on the earth's surface.
The Amazonian rainforest in brazil has nearly five hundred species of trees growing in an area of just two and half square miles.
Compared that to the total area of the unites state and Canada, which combine, have only about 700 species of trees.
But just why the discovery of tropical biodiversity consider so important Because not only did it enable scientists to better understand the natural systems at that work here But helped them began to harvest and extraordinary rearrange the sources which touch our life every day.
From the production of more food and better industrial products to the development of new medicines For example, many of the most promising anti-cancer drugs come from plants found in the world tropical rainforests.
But those benefits have come up a deep price Scientists estimate that loss of tropical biodiversity is happening at an alarming rate.
Millions of acres of habitats have been out countless species have gone distinct It's estimated that with the current rate of deforestation All tropical rainforests could disappear by the year 2030 That disappearance has far-reaching environmental implications Because as our next great discovery revealed all the earth biological systems and the community of life that depended on them are connected The dust ball of nineteen thirties After years of drought the once fertilized America mid-west became a waste land.
Without rain, farmers continued to plow and plant Hoping that the nutrient in the field would somehow be replenished.
But their efforts only made things worse.
The top soil turned to dust And the wind took its avenges For British ecologist Arthur Tensely, the dust ball was proof that scientists and the public in large Were too narrow when they are view of the physical and biological world They did not understand the dynamic of the environment as a whole.
A perspective that helped to explain the cause and effect of events like the dust ball He advocated a new concept, what he called the ecosystem The world has simplicity to its understandable by the ordinary person that can be applied effectively Also has a scientific significance in the apt it brings together ideas form variety of sciences To understand the impact of Tinsley's idea, I paved a visit to Frank Golley state botanical garden in Athens Georgia Why was this a revolutionary shift in thinking At that time, ecological work was a strongly involved with the description in the nature And the system approach, you are actually is going further your experimenting You are looking for patterns That are persistent across a variety of locations and species And then you make statement about the way they perform that can be tested Its moves ecology into the same value as physics and chemistry and molecule biology So, Tensely took the word system and applied it to ecological studies.
He tried to convey the idea that ecology is part of a hierarchy physical system at the universe at one extreme To the atom and the other So, that's someone may be the solar system Yes - And down blow that would be ecosystems, - Yes Back here is something I want to show you, the quantity of silt that you see in the river right now.
Is due to the erosion of the farmland that upstream This is a opportunity to see what we could say is a ecosystem defined physically.
Bill, right here, in front of us.
So, this is a flood plain that's right As we see the water from the Oconee river.
Periodically we get enormous rainfall and the river floods And would then, send the water into this sort of area Would might be we might be stemming just deep in water during a flood.
Presumable at one time, it was a forest See the reminisce of the trees.
But because the floodingand, persistence of flooding, the tree's roots were unable to respire and the trees died you can see if you look yourself around here how beautiful before they recovering forest and its shape We've study that in great detail, using an ecosystem approach So, we are able to talk about the how to rebuild ecological systems here in this region But manipulating the very species and the environment to speed up the process to get the .
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we want to amply size and to do it at the blast cause, And that's a very positive step Cause we can rebuild nature to meet certain human needs And so it has functions and maintains itself honestly own under solar power.
Solar power yes Under solar power Which is driving all the cycle s and everything else.
Our journey through the greatest discoveries in the history of biology has revealed an amazing diversity of life on earth.
And it has given us an insight at that how life works From a life cycle of a smaller cell, to the system that governs the physical environment of our entire planet But there is one insight that .
.
all above others is this.
The search for more discoveries about life is never ending.
That journey goes on forever