1. An animated tour about DNA and genes: http://learn.genetics.utah.edu/
DNA The Code of Life
Medical Detectives
© 2013 Project Lead The Way, Inc.

2. What is DNA?
DNA (deoxyribonucleic acid) is the genetic material in all known living organisms and some viruses
It can be carried from one generation to another
This website can give you some more information about DNA:

3. The “Code of Life”
Information in DNA determines an organism’s characteristics
DNA consists of base pairs Adenine, Thymine, Guanine, and Cytosine
The base pairs arrange themselves in a specific pattern. Adenine pairs with thymine. Guanine pairs with cytosine. This makes DNA replication a lot simpler. The picture on this slide explains a specific code. Game for students to see how DNA pairs up.

4. The “Code of Life”
DNA can be compared to a cookbook with instructions about how to create and maintain a specific living thing.
Genes can be compared to the individual recipes in the cookbook. They encode the information to make proteins and determine how many of those proteins to make.

5. Packaging DNA
The basic structure of DNA is that of a twisted ladder called a double helix.
To fit into the nucleus, the double helix wraps around proteins called histones.
Histones-proteins around which the DNA winds

6. Packaging DNA The DNA then condenses into chromosomes.
Human beings have 46 chromosomes in the nucleus of almost every cell.
Chromosomes of a human male

7. DNA Structure

8. DNA Extraction Step 1: Collect cheek cells
Sports drink is used as a mouthwash collection medium.
Sports drinks contain salt in a concentration similar to the cheek cells; this prevents the cells from breaking open and releasing their DNA before they are collected.
During the extraction, remind the students about the importance of histones. Additional Resource – DNA Extraction Virtual Lab:

9. DNA Extraction Step 2: Cell lysis
The membranes that surround and protect the cell and nucleus must be broken to release the DNA in a process called cell lysis.
A detergent-based cell lysis solution will be used to degrade the membranes.
The remaining solution is known as cell lysate.

10. DNA Extraction Step 3: DNA precipitation
The DNA in the cell lysate is in solution and is not visible (like sugar in water).
DNA is insoluble in ethanol (like sand in water).
DNA from the cell lysate can be visualized by applying a layer of ethanol on top of the cell lysate.

11. Importance of DNA Extraction
DNA extraction is the first step in many in-depth experiments including:
The study of heredity
Potential treatments of diseases
Extracted DNA can be used to create DNA fingerprints to help:
Diagnose genetic diseases
Solve criminal cases

12. Image Resources
By KES47 (File:Chromosome zh.svg) [CC-BY-3.0 ( via Wikimedia Commons
Free images courtesy of Wikimedia Commons