But what's the difference between the eggs you use to make your breakfast

and the eggs which make a chicken? To find the answer

we need to investigate the secrets life which start

with your genes.

All living things are made of cells, but to understand how to make a living thing

we need to look inside a cell.

So your body is made around 50 trillion cells. But in order to see

them we need to zoom in and study them on a microscopic scale.

So first of all, I need to take a swab of my own cheek cells

and then we're going to apply a blue dye

in order to see them. We've magnified this image by two hundred times

and if we look at this dark spot just here...

this is the nucleus of the cell, and this is what we can find something called chromosomes.

Chromosomes are made of DNA

which is divided into sections called genes.

These genes contain the instructions for living things

everything from making new cells to the colour of feathers.

To make an entire human

you need 23 pairs of chromosomes containing

20 thousand genes written in the language of DNA.

Different animals have different numbers have chromosomes

where we had 23 pairs a chicken has 39 pairs.

But what have chromosomes got to do with your breakfast?

So to tell us a little bit more I'm here with Joel and we've picked up some eggs

from the supermarket

but Joel is there any chance of these eggs having a chicken inside them?

So it's very low chance these eggs will have chickens inside them because

the hens that laid these eggs

will not been kept with the cockrels. Okay then, so how can we go about proving that?

So the definitive test will be to crack the egg open and to

take a look inside. All right, let's crack it open. So what are we looking for here?

So we're looking for something called the 'blastodisc' which is the small white

spot that we can see on the surface of the egg.

And what exactly is that? So this is where we find

half of the chromosomes - half the genetic information -

from the hen. So how would a hen go about getting

a full set of chromosomes and all of that genetic information?

So a hen would need to mate with a cockrel

and the cockrel's sperm would fuse with the

genetic information from the hen to fertilise the egg

we then have two sets of chromosomes. And the blastodisc is the point at which that

fertilisation actually happens? Yeah, so this is where fertilisation would

happen and this is where

the embryo - the actual chicken - would start to develop from that point.

In humans this development of the embryo

is called pregnancy and it happens inside the womb

over nine months. But in chickens this gestation period

takes place inside the egg over just three weeks.

And finally after that time you get a new life.

To unlock more secrets a biology check out Nerys dissecting a brain.

Stay tuned to our YouTube channel because next week we'll be running a live

stream it directly from the hatchery.

So if you'd like to see the chicks hatch for yourself, click subscribe.

Thanks for watching.