🧬 Lesson 2: How Genes Make Cells, Tissues, Organs

What Are Genes? And How They Build Every Living Thing

👶 It All Starts With One Cell

Before you were born, you started as one tiny cell.

That one cell had your full DNA inside it — with all your genes.

And your genes got to work!

They gave instructions to:

It’s like starting with one LEGO block and ending with a giant castle!

Your first cell didn’t stay alone.
It copied itself and made more and more cells.

Each new cell had the same genes, copied perfectly.

And as you grew, your genes said:

So, the same DNA can build many kinds of cells, just by reading different genes.

Once your body had many cells, they started working together.

When similar cells join up, they make something called a tissue.

Examples of tissues:

Think of a tissue like a team of workers doing the same job.

Now it gets really cool.

When different tissues join together, they form an organ.

An organ is a body part that does an important job.

Examples:

All organs are made using instructions from your genes!

Your body is like a super machine made of:

And all of it started with genes.

Without genes, your body wouldn’t know what to make or how to grow.

Here’s the secret:

They don’t know.
They just follow rules that work.

The genes that gave good instructions were passed on again and again.

The ones that gave bad instructions disappeared.

Over time, this made bodies better at staying alive.

So it feels like genes are “smart,” but really, it’s just nature keeping the good ones.

A tiny baby starts as one cell.
That cell reads the right genes at the right time.

That’s how:

Your genes are like builders following a super old blueprint — one that’s been passed down for millions of years.