The fingerprint that’s inside your body!!!!!! DNA The fingerprint that’s inside your body!!!!!!

Expected Learning - to extract DNA from wheat germ - To describe the structure of the DNA molecule - to find out how DNA evidence is used by CSIs

DNA

Fun DNA Facts! DNA is too small to see, but under a microscope it looks like a twisted up ladder! DNA stands for: D: Deoxyribose N: Nucleic A: Acid Every living thing has DNA. That means that you have something in common with a zebra, a tree, a mushroom and a beetle!!!!

Let’s get DNA from some wheat germ! Activity # 1 Let’s get DNA from some wheat germ!

9-CSI- ’DNA Extraction’ Chemicals Equipment Detergent Lge. Test Tube Cold Alcohol Stirring Rod Measuring Cylinder Wheat Germ Pipette Collect a large test tube with I spatula of wheat germ. Measure 20 ml of hot water from the kettle and add it to the test tube. Using the stirring rod; mix continually for 3 minutes. Add 10 drops of detergent and mix for a further 5 minutes. (Be very careful not to make it foam.) If it is frothy on top, you will need to use the pipette to suck the bubbles off. Tilt the test tube and slowly pour in 10ml. Alcohol so that it forms a layer on top of the water. DO NOT MIX the two layers Let the test tube sit for a few minutes. The DNA will appear as white stringy matter at the interface between the two liquids. Use the hook to lift some out and have a closer look. ADD 10 drops detergent Stir for 3 minutes Stir for 5 minutes Now have a closer look at your DNA Cold Alcohol Hot water DNA Wheat Germ Wheat Germ Wheat Germ

DNA is made up of steps and rails of a ladder. This is a rail This is a step Green can only go with Red Purple can only go with Yellow

Let’s make our own DNA molecule. Activity # 2 Let’s make our own DNA molecule.

You can tell people apart by their fingerprints… Because everyone’s fingerprints are different!

DNA is like a fingerprint because everyone’s is a little different! How does the police look at DNA to figure out who committed a crime?

STEP # 1 The DNA gets cut up by special scissors!!!

The scissors can only cut the same colour!

All of the cut up pieces of DNA are different sizes. STEP # 2 All of the cut up pieces of DNA are different sizes.

STEP # 3 A special machine sorts the DNA by size. (Little pieces are fast, so they move faster to the bottom.) BIG TOP LITTLE BOTTOM

We are ALL a little bit different! Miss Ellis’ DNA BIG LITTLE Sara’s DNA

Soooo…. How do we tell people apart just by their DNA anyways???

Our DNA has different sizes of pieces so it makes a different pattern when it’s all cut up. Miss Ellis’ DNA Sara’s DNA

This is what it really looks like!!! Miss Ellis Sara                                                                                                   This is what it really looks like!!!

Can you guess which one is Sara and which one is Miss Ellis? Is the red box around Miss Ellis’ DNA or around Sara’s DNA?