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. DO NOW Tuesday September 13th
What is the name of gene responsible for HD?
What is the mutation in this gene?
What kind of molecule do genes code for?
How does this mutation result in damage to brain cells?

3. PLAN
Analyze how changes in the huntingtin gene affect the resulting protein and nerve cell function.
Use appropriate laboratory methods to isolate DNA from cheek cells. DO
Check Thursday’s classwork in journals.
Discuss DNA structure and answer questions in your biomedical science journal to prepare for tomorrow’s DNA Isolation Lab.

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

5. The “Code of Life”
Information in DNA determines an organism’s characteristics
DNA contains 4 nitrogen bases: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C)
A pairs with T in DNA
G pairs with C in DNA
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.

6. 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.

7. 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

8. 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

9. DNA Structure

10. DO NOW Tuesday September 20th
Consider the pedigree above. Explain why
Jack’s daughter has a 50% chance of
having the gene for Huntington’s disease.

11. PLAN
Use appropriate laboratory methods to isolate DNA from cheek cells. DO
Genetics/HD Quiz
Finish questions over DNA Isolation Lab
Discuss Lab
Conduct Lab
Discuss Inherited diseases while waiting for DNA to precipitate

12. 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:

13. 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.

14. 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 (wont dissolve) in ethanol (like sand in water).
So we add the ethanol to cause the DNA to precipitate (come out of solution) so we can see it.

16. 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

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