Practice English Speaking&Listening with: Gregor Mendel: Great Minds

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Today I have for you: A sizzling tale

of a chubby little friar who changed the world

with a garden full of pea plants.

Today's Great Mind in Science is Gregor Mendel,

an Austrian monk who in [the] mid-18-hundreds

single-handedly fathered modern genetics!

But even though Mendel was a man of God, as it were,

he and his pea plants have been the focus of

one of the biggest scientific scandals in history.

Oh Lord, I love a good scientific scandal!

[intro music]

Mendel was born in 1822 in what was then Austria, but is now the Czech Republic.

His parents were super super poor, but the young Gregor was such a precocious little scamp

that they spent all of their money educating him.

That is, at least until his dad was injured in a farming accident, which,

I imagine is the Number One occupational hazard associated with being a pre-industrial revolution Austrian peasant.

His family did what they could to help him out,

but eventually, Mendel decided that being an Augustinian monk didn't seem so bad.

Now, I point out that the given historical record of Mendel's life and work

are pretty spotty actually because the priests who dealt with his personal effects

after his death got rid of almost everything, not knowing

how extraordinarily important it all was.

But one of the very few of Mendel's papers that survived

had Mendel let on that he was not "called" to the church,

as some people were.

"My circumstances decided my vocational choice." is how he put it.

Anyway, in 1843 Mendel moved into the monastery at Brno (Brünn), Austria,

and it turned out to be a pretty good move for him, because he basically got sent to college for free,

and - y'know - dating is such a /drag/, who needs that anyway?

After a failed attempt at becoming a science teacher,

he started spending all of his free-time

in the gardens with some common-garden peas,

and, being a scientist at heart, he started

doing experiments on them.

For the record, right now, YOU, and I don't care who you are,

YOU know much, much more about how heredity works than Mendel did,

when he started. Not to mention chromosomes and DNA.

At the time, microscopes weren't good enough to even observe basic cell division,

so nobody knew dog squat about how sexual reproduction worked.

In Mendel's Day, it was generally thought that making a baby was

putting the parents genetic material into a blender and just mixing it up, real good.

People assumed for example, that if a white squirrel and a black squirrel had babys, their offspring would be gray.

What Mendel discovered, after whispering sweet nothings to a yard full of pea plants for eight years,

was that this line of thinking was exactly, entirely wrong.

Mendel set us straight on the fundamental properties of inheritance,

which eventually paved the way of the development of modern genetics.

Mendel's choice of research subjects for this endeavour was shockingly perfect,

for one important reason: The traits that he studied

color of pea flowers, and color and texture of the peas themselves,

are only determined by a single gene.

This turns out NOT to be the case for almost every physical trait in most organisms.

In fact, the vast majority of inherited traits are either the product of

two or more genes working together to determine, say, eye color or ear shape

Or, the product of one trait having a hand in a bunch of physical traits.

How did Mendel know that? HOW DID HE KNOW?

Well, he probably started out by noticing that the flowers of his pea plants in the garden

were purple most of the time, but then every once in a while,

they produced white ones.

Since he studied inheritance in college he knew that the way to get to the bottom of this

was to create a true breeding line of purple flower peas, and a true breeding line of white flower peas.

So he brought the purple ones together,

for successive generations until he was getting purple flowers all of the time, and did the same thing for the white ones.

Having done this, Mendel then started a series of extremely methodic experiments

in which he bred purely purple-flowered and the purely white-flowered plants together.

And in doing this, for successive generations he eventually realized:

"/Gott im Himmel/, (God in Heaven), the pea flowers are white almost exactly one quarter of the time!

This led him to three important conclusions.

Important conclusion #1, Mendel discovered that pea plants were inheriting a pair of genetic instructions from each parent.

Sometimes, both instructions from the parents would tell the flower to be purple,

sometimes they'd both be for white flowers, and sometimes, there would be one instruction for each.

Mendel called these versions of a gene passed from parent to offspring "factors".. But these days, we call them alleles.

And so the baby pea plant had two alleles for flower color.

One chosen randomly from Mom and one chosen randomly from Dad.

And these genetic instructions, these genotype as we call it now,

decided what the outward appearance of the pea flower, the phenotype, was going to be.

Important conclusion #2:

Mendel also found that the allele for purple flower was stronger, or more dominant, than the white allele,

which was recessive. Since the purple allele was dominant, and the white was recessive,

the plant inheriting one purple and one white allele would produce purple flowers.

Important conclusion #3:

Even though the purple allele was dominant, that didn't mean that it was tossed into the mix more often.

it was just being /expressed/ more often.

In fact, Mendel concluded that which trait a parent would throw into the ring, purple or white, was totally random.

But a dominant allele was always going to trump a recessive allele.

So through these three conclusions, Mendel came up with the hard and fast rule about genetic inheritance

Mendel's first law, or the law of segregation.

That says that every individual possesses two alleles, for any particular trait,

like for example flower color - and which allele a parent gives its offspring is completely random.

The offspring then has one allele from Mom, and one allele from Dad,

and of those two alleles, the dominant one is the one trait that the offspring will express.

If and when both of the alleles happen to be recessive, only then will the recessive trait be expressed.

But Mendel went even farther [sic] with his pea plants,

and no, I not going to shut up about pea plants! It's fascinating, okay?

And he got similar results in his experiments on his seeds of the pea plants.

...which are the peas.

He discovered that two traits of the pea,

its color, and its skin texture, had nothing to do with each other.

Now, his peas could either be green or yellow in color, either have smooth or wrinkly skin.

Mendel found that when he took a smooth yellow pea, crossed it with a green wrinkly pea,

he could, with the same mathematical precision as he did with the flower,

predict the ratio of yellow smooth, yellow wrinkly, green smooth and green wrinkly peas.

So the other rule Mendel contributed to our understanding of genetics is Mendel's Second Law,

or the law of independent assortment.

Which says that seperate genes are passed independently from each other from parent to offspring.

In this case, two dominant traits in peas, the wrinklyness and the yellowness,

were unrelated. Pretty big deal, right?

Well, Mendel ended up writing a paper called:

"Ver-soot-sssh oober pflantsen hye-breden", ("Versuche über Planzen-Hybriden"/Experiments about plant hybrids),

if you "spreken see deutsh" ("Sprechen Sie Deutsch"/ Do you speak German)

which clearly, I do not.

and it was published in a weekly scientific journal, and he presented his finding to the equivalent of some

19th century garden clubs.

He also sent his paper to every fancy-pants scientist he could think of,

but here's the thing: the big shots don't like to take notice of him, because, none of them

knew what the hell he was talking about.

Mendel's work was so far ahead of its time, that his experiments

didn't even make sense to his contemporaries.

In fact, his data didn't become useful to researchers until nearly 35 years after he published them.

So Mendel was, for another 20 years or so after he published his findings, on all accounts, he was a totally happy dude.

He became the abbot of the monastery,

and he had a lot of smart friends who liked to talk science.

His doctor had him smoking 20 or so cigars every day, to help him lose weight -

NOT an effective strategy, if anybody's interested...

But he was never recognized for the monumental contributions he made to science during his lifetime.

But then, around 1900 scientist were independently working on what Mendel had already discovered,

because there were a lot of people still going around hollering:

URRRGH - WHITE SQUIRREL, BLACKS SQUIRREL MAKE GRAY SQUIRREL!!

Which was by now, becoming more and more obviously wrong.

Microscopes had gotten a lot better and more powerful,

and people were observing chromosomes - they had no idea what they /were/, but they were observing them.

And it wasn't until a group of scientist dug out Mendels papers,

and applied his laws to discoveries that had been made since,

that everybody working on heredity, put down their beakers, and were, like:

Ooooh!

and suddenly the scientific reading went totally bonkers for Gregor Mendel.

He was heralded as the father of modern genetics,

and they made a little special shrine to him at his test garden at the monastery,

and scientists would make pilgrimages there, to weep over his hoes and shovels and stuff!

Okay, I dunno about that last part.

But, the point is, that suddenly

Gregor Mendel became a very big deal.

And then, in 1936, a statistician named Ronald Fisher

published a paper, examining the data.

Fisher was, like, "hey, you guys? Umm - I love Mendel and everything,

but have you looked at his data? They're [sic] really good, like, /reeeally/ good, like, maybe,

statistically implausible."

Fisher was a statistician, a geneticist, and a big Mendel fan,

so in his research of Mendels paper, he admitted

that in a lot of ways, Mendel

really was the methodical genius superhero scientist that everyone gave him credit for being.

But he also saw that all of Mendel corroborated his theory really well.

Like, data turned out to be eerily perfect for thousands of plants, in dozens of experiments.

conducted over the 8 years. So Fisher,

was like, "In conclusion, someone might have probably kind of fiddled with Mendels data.

But it definitely wasn't Mendel...

could've'been - one of his assistants, maybe?"

Because, y'know, Fisher hated to do it, he buried most of the really incriminating evidents

about the data fiddling in the back of the paper.

And some people read it, but most people didn't, so it didn't cause much of a kerfuffle.

At first.

But when the Mendel centennial celebration came along in the 1960s,

some people dug up Fisher's paper, and all of a sudden,

the scientific community went all Animal Planet on Mendel.

Like, this guy -

he existed before science!

so you can't give him a super hard time about being, like,

"Well, I must've crossed that pea wrong. Don't include that one in the data."

He didn't know about science!

This was before...

well, this was before good science was being done, he was a monk.

Give him a break!

Even now, there are Mendel-Fisher controversies afficionados out there and talk about the stuff till the lights go out.

Nearly 50 years later, people are writing books, and

papers about him, most of'em trying to prove Mendel was completely faultless.

but no one has been able to explain what Fisher

the apparent data fiddling, selective reporting, omission...

whatever you wanna call it.

The important thing is, that Mendel put us all on the right track

and of course, genetics ended up way, way, waay, /way/, WAAAY more convoluted

than Mendel's work could explain. But what Mendel gave us

a firm hypothesis on which to base other studies by countless other geneticists

who worked to discover and understand chromosomes and DNA in the 20th century.

Today, traits that have been shown to operate under Mendel's Law, like albinism,

are known as Mendelian Traits.

There are lists of these traits in humans and in other animals, I put some links for those down in the description.

If you have an idea for a Great Mind which you like us to profile,

please let us know through the Twitters or the Facebooks,

or of course, in the comments below.

If we picked your idea, I'll give you a shout-out in that episode

either that, or I can send you a ziplog bag full of my shaved whiskers,

whichever you want best.

[outro music]

The Description of Gregor Mendel: Great Minds