👋 Welcome Back!

By now, you know this:

• Genes are recipes

• They help your body make proteins

• Each protein has an important job

But here’s something we haven’t fully answered yet:

Where exactly do these genes live?

Do they float around in your blood?
Do they sit in your brain?
Do they hide inside your bones?

Let’s go on a journey — deep inside your body — to find out.

🧪 Your Body Is Made of Cells

Your body is not one big thing. It’s made of trillions of tiny pieces called cells.

Cells are like little jelly bubbles. They are super small. You can only see them with a microscope.

Different kinds of cells do different jobs:

• Skin cells keep you safe

• Muscle cells help you move

• Brain cells help you think

• Blood cells carry oxygen

And guess what?

Almost every single cell in your body has your full set of genes inside it!

Every. Single. One.

🏠 Where in the Cell Do Genes Live?

Let’s zoom into a single cell now.

Inside that tiny jelly bubble, there’s a smaller part called the nucleus.
The nucleus is like a little round room inside the cell. It’s the control center.

That’s where your DNA lives.
And inside your DNA are your genes.

So:

• Genes live inside DNA

• DNA lives inside the nucleus

• The nucleus lives inside the cell

• The cell is part of your body

It’s like a house inside a house inside a house inside YOU!

🧵 DNA Is Super Long — But It Fits Inside the Nucleus

Here’s something wild:

If you stretch out all the DNA in just one of your cells, it would be about 2 meters (6 feet) long!

But your cells are super tiny. So how does all that DNA fit inside?

The answer is something called chromosomes.

📦 What Are Chromosomes?

Think of chromosomes like tightly packed boxes for your DNA.

Your DNA gets wrapped and folded into neat shapes, like yarn wrapped into balls.

Each of these neat balls is a chromosome.
Inside each one are thousands of genes.

Humans have 46 chromosomes — 23 from your mom and 23 from your dad.

They are all stored inside the nucleus of almost every cell.

🧬 Each Chromosome Holds Many Genes

Each chromosome is like a bookshelf.
Each gene is like a book sitting on the shelf.

The shelf doesn’t do anything by itself — it just holds the books in place.

When your body needs a certain recipe (gene), it opens up that part of the chromosome and reads it.

So:

• Chromosomes = Hold the DNA

• DNA = Holds the genes

• Genes = Give the instructions

Everything is folded, packed, and stored in a super-smart way.

👨‍👩‍👧 What Makes You You?

You get half your chromosomes from your mom and half from your dad.

That means your body has a mix of genes from both.

That’s why:

• You may have your dad’s nose

• But your mom’s smile

• And maybe your grandma’s hair!

Your genes carry the history of your family, all wrapped into tiny boxes called chromosomes.

🧬 Are Chromosomes All the Same?

Nope!

Chromosomes come in pairs — each pair is like a team.

Most people have:

• 22 pairs of regular chromosomes

• 1 pair of sex chromosomes (these decide if you’re biologically male or female)

Boys usually have an X and a Y
Girls usually have two Xs

This one tiny difference can change how the whole body develops.

🧠 Fun Fact: Chromosomes Are Numbered

Scientists gave each pair of chromosomes a number — from 1 to 22.

Some chromosomes are big, and some are small.

The genes are spread across them like puzzle pieces.
You need the full set of pieces to build a full human body.

⚠️ What Happens if Something Is Missing?

Sometimes, a person might be born with:

• A missing chromosome

• An extra chromosome

• A broken chromosome

This can cause the body to grow differently or work in a new way.

For example:

• Having an extra copy of chromosome 21 causes Down syndrome

• A missing X or Y chromosome can change how the body grows

These things don’t mean a person isn’t smart or kind.
It just means their body works in its own unique way.

🕵️ Do All Animals Have the Same Number of Chromosomes?

Nope! Every species has its own number.

• Humans: 46

• Dogs: 78

• Cats: 38

• Chickens: 78

• Elephants: 56

But it’s not just the number that matters — it’s what genes are inside that counts.

Even if another animal has more chromosomes than you, they won’t become smarter or taller.
They just have a different instruction book.

🎯 Let’s Review!

✅ Your body is made of cells
✅ Inside each cell is a nucleus
✅ Inside the nucleus is DNA
✅ DNA is packed into chromosomes
✅ Each chromosome holds many genes
✅ Humans have 46 chromosomes
✅ You get half from your mom, half from your dad
✅ Genes are stored safely inside every chromosome
✅ Chromosome changes can make bodies grow in different ways