The Double Helix Explains How DNA Copies Itself

Lab Brief #4

🎯 Your mission

Set it up. Test it. Be amazed.

⚡ The twist

Nature loves to surprise the careful watcher.

What you'll learn

DNA is two strands running in opposite directions, held together by base pairs in which adenine always pairs with thymine and cytosine with guanine. That pairing rule is not decoration, it is the mechanism: separate the two strands and each one specifies its partner exactly, so one molecule can produce two identical copies. Watson and Crick published the structure in 1953 and pointed out the copying mechanism in the same paper, because the structure made it obvious.

Key words

base pairing
The rule that adenine pairs only with thymine and cytosine only with guanine across the two DNA strands.
replication
The copying of DNA, in which the strands separate and each acts as a template for a new partner strand.

Make a hypothesis first

Before you start: write down what you think will happen, and why.

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

coloured card
scissors
sticky tape
ruler

⚠️ Safety first

Use scissors carefully and cut away from your fingers.

Step 1 of 4 · Read

Think about what you just learned: say what "base pairing" and "replication" mean in your own words before you start.

Step 2 of 4 · Do

Build a 10-base-pair DNA model from card strips, obeying the pairing rule. Then split it down the middle and rebuild both halves from spare bases, checking that you recover two molecules identical to the original.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 3

In DNA, adenine always pairs with:

How sure are you?😐 maybe

Question 2 of 3

Base pairing explains replication because each separated strand:

How sure are you?😐 maybe

Question 3 of 3

The DNA molecule is described as a double helix because it is:

How sure are you?😐 maybe

Mind = blown

🔬 The more you look, the more nature shows you.

Nice work!

You got 0 of 3 right.

Next: From Gene to Protein to Trait All lessons

🎯

Next Smart Experiment

We'll pick an experiment that matches exactly how you're thinking right now.

✨ More to explore

🌍 Where you see this in real life: This shows up in your everyday life more than you'd think.

🏆 Stretch challenge (try it this week): Try one experiment in real life this week — even a tiny one.

👨‍👩‍👧 For the dinner table: “What's the most surprising thing you learned today?”

🧬Share card

Share this experiment

Send it to a parent who's looking for a 10-minute kitchen science win.

The Double Helix Explains How DNA Copies Itself

Next Smart Experiment

Share this experiment

The Double Helix Explains How DNA Copies Itself

Done with science? Try something else

Your Cart (0)