Transcription
Hey, nice jeans!
Thanks! I got them from my mom and dad.
Me too! Wait, that means we must be the Science Guy Bill!
N the Science Guy Bill!
The Science Guy!
Science!
[Music]
Rules!
Inertia is a property of matter.
The Science Guy!
T-7 Seconds!
The Science Guy brought to you by the Double Helix Corporation. We build foundations for life.
The way you are when you're born depends on where you came from. It's determined by your parents. Your body and your brain are made with a set of instructions that determine who and what you are.
Now, the way you are comes from what we call your genes, and you get your genes from your parents.
Genes are in every living thing on Earth. Genes are stored on extremely long strands of chemicals that are in almost every cell of your body.
The way you are and the way you look when you're born are controlled by your genes.
Take a look at this! It's our microscope with a camera!
Microscope of Science!
And right now, it's taking a picture of a very small part of a tiny droplet of blood.
You can see that there are little compartments. These are called cells.
Your whole body is made of cells. You've got brain cells, eye cells, stomach cells, and skin cells.
Now, inside each cell, there are very, very small bundles of chemicals. This is about all we can see with a microscope like this.
But with a very powerful imaging technique, you can see that those bundles of chemicals are made of another chemical. It's called DNA.
Maybe you've heard of it? That stands for deoxyribonucleic acid, and it's shaped like a ladder that's been twisted.
DNA has all the information you need to determine whether or not you're a tree, a human, a sea jelly, whether you've got red hair, black hair, green eyes, or dark skin.
And not only that, DNA is made of just four main chemicals, and they fit together either like this, uhhuh, or like this, right?
Now, how can that be? How can all that information be packed into such a tiny space?
How could one chemical make all these different kinds of living things in all these different shapes and sizes?
How can it be?
I'll show you!
[Music]
Take a look at this! It's our DNA string reel model of science!
Now, if the DNA molecule were as wide as this string, it would be this long—about 200 km, a billion times longer than it is wide.
And your genes are strung out on this!
[Music]
Molecule!
That's a big molecule!
It's huge!
It's in your jeans!
Deoxyribonucleic acid, DNA, is the chemical genes are made of.
Thousands and thousands of genes are joined together to make a chromosome.
So chromosomes are very, very long DNA molecules.
Chromosomes are found in almost every cell of every living thing.
This is a chromosome. It holds lots of [Music] genes.
This is a gene. It's a specific piece of DNA.
Here's another gene, another, another.
All these genes make up one long piece of [Music] DNA.
Oh, Ken, I think I got something here!
Yeah, I think you got something there, Bill!
This right here is a white blood cell, and these are three red blood cells.
Uhh, and you'll notice that the white blood cell is staying much darker than the red blood cells.
That's because it has a nucleus!
That's right!
And look right there! See those dark strands right there? That's DNA!
Yes! DNA!
Woo! Right there!
DNA!
DNA!
Yes!
Can we get the next slide, Bill?
Oh, oh, oh! Yeah! Check it out!
So this is the nucleus of the cell, all squashed flat.
These right here are the long strands of DNA, all coiled around each other.
These are called chromosomes!
Let's stretch it out!
Sure!
Pure DNA!
Stretch it out, Bill!
It's long!
Str DNA!
So what do we do with this?
Well, we can take this and cut it up into little pieces and separate those pieces.
We can then move them from one organism to another.
Here's an example that I prepared earlier.
This is a protein from a sea jelly that we've taken and put inside of a bacteria.
Now the bacteria fluoresce under UV light just like the sea jelly!
Whoa!
W!
Now this would be a piece of the huge DNA molecule.
It looks something like this!
See, this is DNA!
It has lots of genes on it.
They're all packed in [Music] chromosomes.
To make an article of clothing, we use long pieces of paper, a pattern.
To make a person or another living thing, we use long pieces of information called genes.
Now here's the pattern to make the left arm of the lab coat.
The pattern provides the information to cut out the cloth.
The same way your genes provide the information to make your left arm.
Now notice that we need a lot of pattern pieces, a lot of pieces of cloth to make a lab coat.
The same way we need a lot of information, a lot of genes to make a person or another living thing.
The information to make these is in the pattern.
The information to make these is in your genes.
Our genes are contained in chromosomes, the basic unit of life.
These combinations of molecules distinguish living things from non-living systems.
Now your genes tell your cells what to do.
And Dad, what is it, son?
What are genes?
Well, Richie, your mother will answer that.
Mom!
Richie, genes are the set of chemical instructions that get passed down from parents to child.
In the process, of course, the genetic material is recombined in new ways, which is why most people bear resemblance to their parents and grandparents without looking like any one relative in particular.
So you mean it's not your fault you had a big nose?
It's because your parents had a big nose!
Richie, eat your crust!
Oh boy!
Huh!
Oh, see you!
Me, giraffes, fish, seaweed—our genes are all made of DNA!
Let me see here!
Let me see!
Um, oh!
Our genes are stored in parts of our cells called chromosomes.
They look like this!
Chromosomes contain all of the genetic information, all the instructions you need to make a person.
Now, humans have 23 pairs of chromosomes for a total of 46.
It's like the instructions are stored in 46 books, and the books are divided into chapters, and each chapter is like a gene.
Now, humans have about 80,000 genes.
It's like we have 880,000 chapters in 46 books.
Now, if you're a cell in a body, you don't need to read every chapter.
If you're a nose cell, you just read the chapter about noses.
If you're a hand cell, you just read the chapter about hands.
If you're an eye cell, you just read the chapter about eyes.
See, in a way, they're all different names for different parts of the same thing: chromosomes, genes, pieces of DNA, books, chapters, letters.
It's pretty good reading!
[Music]
Each chromosome has in it genes that are the units of information.
Most species have fewer than 100 chromosomes but thousands and thousands of genes.
Every one of your cells has 46 chromosomes—that's 23 pairs!
So it's like you got 23 socks from your mom and 23 socks from Dad.
And the chromosomes from your mom pair up, and they almost, almost match from your dad.
But the genes, the stuff that the chromosomes are made of, are slightly [Music] different.
Genes determine a lot of different things, like what color your eyes are, or how long your toes are, or even your sense of humor probably comes from your genes!
You better give that back!
Oh, look at these bundles of genetic code!
Oh, cute!
Actually, they're babies!
I was a baby once!
Mhm!
Those were the days!
I grew out of it!
You and me and every person became a person the same way!
Like this!
Here's a picture of my mom and dad.
Now, to make a person like me, I got a special reproductive cell from my mom called an egg, and I got another special reproductive cell from my dad called a sperm.
Now, each of these cells only has half of the chromosomes, half of the genes you need to make a person.
But they combine in a sort of genetic square for theosis, and this one new cell grows into somebody like me!
You know what? Let me show you my baby pictures!
See, here's one of the chromosomes I got from my dad, and here's one of the chromosomes I got from my mom.
And here they are combining!
The egg is being fertilized by the sperm.
Then this brand new combination of genes immediately springs into action to make the new cell grow.
And that one cell divides into two cells like this!
But these cells keep dividing and dividing and dividing, so you have all 50 trillion cells you need to make a whole new person!
Like these little bundles of genetic code!
Ribonucliec acid, DNA, is a molecule containing the genetic message, the blueprint for future generations.
This genetic code is the same for all living creatures, for all life, which means that there is really only one form of life on Earth.
You could do a genetic experiment at home!
Just look at your earlobes!
Are they attached like mine, or do they dangle?
Well, the shape of your earlobes depends on your genes.
Some people have a gene for dangling ears, and some people have a gene for attached earlobes.
Wait! Come with me!
Come back!
It's kind of hanging, but it's kind of attached right there!
You know what, Micha? I inherited that!
It's pretty much attached, right?
What's wrong with my ears?
They hang in pretty low!
They hang in pretty low!
You have big ears!
Thanks!
Yeah!
Mhm!
If your parents' earlobes are attached, then yours probably are too.
And if your parents' earlobes dangle, then yours probably dangle also!
'Cause we get our genes from our parents!
Look! Just check it out!
Here's a model of a gene, of a piece of the DNA molecule!
Human genes can combine in about 70 trillion different combinations, and we do it with just four chemicals!
Please consider the following: every living thing— you, me, earthworms, and trees—are made of DNA.
And the DNA in all of us is made of the same four chemicals!
Is that right?
The way it works is that the four chemicals are arranged in a different order or sequence in all the different strands of DNA.
Got it?
And the four chemicals are adenine, thymine, cytosine, and guanine.
Now, each chemical is pretty complicated, don't get me wrong, but there are only four of them: adenine, thymine, cytosine, and guanine.
Now, you might think that with just four chemicals, we'd only be able to get a few combinations, like we'd have an A next to a T or a C next to a G with an A over here.
Here's the thing: you're allowed to use each chemical as many times as you want!
So we end up with thousands and thousands of different combinations!
For example, if we could print out all the chemicals in just one gene—let's say the gene for my hair color, which is not quite red and not quite brown, it's somewhere in between—if we printed it out on pages like this, the gene for my hair color would take five pages!
And that's just for my hair color!
To print out all of the pages we'd need for every human gene, we'd need a lot of paper!
We'd need this much paper—almost half a million sheets—all laid out like this!
So you might think the genes are complicated, but in a way, they're kind of simple 'cause they're made of just four chemicals: adenine, thymine, cytosine, and guanine!
That's it!
And that's it!
Consider that each living thing has its own special blueprint for its species.
Now, the amazing thing is that the blueprint for every single living creature on Earth is composed of the same kind of molecule, which scientists know as DNA—deoxyribonucleic acid.
Deoxyribonucleic acid!
We usually just call it DNA!
This is a mule foal!
He is the offspring of a female horse and a male donkey.
First of all, a mule is a hybrid.
A mule has 63 chromosomes.
A donkey has 62 chromosomes, and the horse has 64.
This is a mule foal!
You get the best genes from the donkey and a lot of the best genes from the horse!
He can carry very heavy loads!
He picks up a lot of this from his father!
A horse cannot quite see that hind foot!
He sees fairly close to that, but a mule will actually see where his hind foot is going in the steep narrow trail!
This is a mule!
They may have a chromosome missing, but they're still a great ride!
Okay, here's what we did!
We took one white blood cell, we smashed it, and we stained it, and it's under this microscope!
And here's what we're seeing right here!
Now, these are chromosomes!
This is a chromosome!
That means bodies that you can see because chromosomes are tightly packed groups of thousands and thousands of genes!
These light and dark bands are bundles of genes, and each bundle contains hundreds of genes!
Those are the genes right there!
Bundles of genes!
It's a specific piece of DNA right there!
Whoa!
Those are the genes right there!
But remember, genes are molecules!
They're chemicals!
They're tiny!
They're much smaller than you can see with even a microscope!
It's like trying to read street signs from outer space!
You can't see them, but you know they're down there!
Whoa!
Like almost nothing!
Just as the chromosomes are paired, so are the many genes that are in them!
I can roll my tongue, but not everybody can!
Let me give you a taste of what's going on here!
Now, there's two kinds of tongue-rolling genes!
One is what we call dominant!
Big R stands for dominant!
And the other is recessive!
Little r for recessive!
Now remember that we get one copy of our genes from our mom and one copy from our dad!
So say you get one dominant gene from your mom and one dominant gene from your dad!
That means you can roll your tongue!
And say you get dominant from your mom but a recessive from your dad, then the dominant overrules the recessive, meaning you still can roll your tongue!
But say you get recessive and recessive from both your parents, then like him, you can't do this!
Come on, try it!
Or you can try this!
Genes have a lot of information, and sometimes the information gets jumbled up!
Take a look at this!
It's a two-headed turtle!
They live here in a zoo!
Now, normally this animal would have been eaten in nature because having two heads, it doesn't get around very well!
Now the mutations that made this animal—the mutations in the gene—happen all the time in nature!
Sometimes the mutations help an animal survive, and other times they don't!
It's all in our genes!
Within the cell is where we are all ultimately defined!
The chromosomes carry the information that reveals our true identities!
We are all of a kind, yet we are all different!
DNA is pretty cool when you think about it!
In fact, thinking's in your genes too!
Danny has a brown-haired father, and Danny has a brown-haired mother.
Turns out Danny has brown hair too!
That was the most likely color!
Mary has a blue-eyed father, and Mary has a blue-eyed mother.
Turns out Mary has blue eyes too!
That was the most likely color!
Mary and Danny had a baby!
So now I'm wondering if maybe, since Danny's hair is curly and Mary's is straight, the baby's hair will be wavy!
You know, it's called genetics!
You know, it's called genetics!
The DNA makes you what you are!
The apple from the tree of... it's a tree!
But what you will be when you take a look, I think you're going to see!
Well, that's our show!
Thanks for watching!
If you'll excuse me, I've got some restriction fragment length polymorphisms to resolve!
See you!
Produced in association with the National Science Foundation!
See, what's happened is we hooked them together!
They've combined!
We recombine them!
That's right!
With this, we can figure out what malaria parasites are doing!
We D—oh hi!
Thanks!
To make an article of clothing, we use paper patterns!
To make a person or another living thing, we use genes!
No!
Yes!
No!
No!
See, you said yes, and I'm saying no!
We're not kidding at all!
Oh, K!
In the process, of course, the genetic material recombines in new ways!
So that, you know, each chemical is pretty complicated, don't get me wrong, but there's only four of them: adenine, thymine, cytosine!
And guanine!
[Music]