1. Forensic DNA Analysis (Part I)

2. Summary What is DNA? Where is DNA found in the body?
How does DNA differ among individuals?
Forensic DNA Analysis
DNA and Statistics

3. What is DNA?

4. What is DNA? What does DNA stand for? What does DNA do?
Deoxyribose Nucleic Acid or Deoxyribonucleic Acid
What does DNA do?
DNA contains genetic information.
DNA codes for the proteins our bodies make that are necessary for survival.

5. AGC TAG CTT ATA CTC TAT CTC TTT
What is DNA?
DNA is a code for making proteins.
AGC TAG CTT ATA CTC TAT CTC TTT
Amino
Acid
Amino
Acid
Amino
Acid
Amino
Acid
Amino
Acid
Amino
Acid
The order of amino acids determines what type of protein is made.

6. Some common proteins are:
What is DNA?
Some common proteins are:
Hemoglobin - carries oxygen from lungs to cells
Insulin - regulates metabolism
Many types of enzymes - catalyze reactions in the body, such as the breakdown of sugar for energy
DNA also determines how much of these proteins each cell makes.

7. What does DNA look like? Double Helix What is DNA?
Like a Twisted Ladder

8. What does DNA look like? What is DNA? Sugar Phosphate Backbone
(Sides of Ladder)
Nitrogenous
Base
(Rungs of Ladder)

9. The DNA ladder is made up of building blocks called nucleotides.
What is DNA?
The DNA ladder is made up of building blocks called nucleotides.
What is a nucleotide?
Adenine
Cytosine
Guanine
Thymine
Phosphate Group
Base
Deoxyribose sugar

10. What is DNA?
The 4 Bases A
Adenine C
Cytosine T
Thymine G
Guanine

11. What is DNA?
The 4 Bases A C T G

12. The 4 Bases A pairs with T G pairs with C
What is DNA?
The 4 Bases
The bases pair up to form the rungs of the ladder.
A pairs with T
G pairs with C

13. AAGTCGATCGATCATCGATCATACGT
What is DNA?
DNA is written as the sequence of these bases:
AAGTCGATCGATCATCGATCATACGT
Only one side of the ladder is written.
In humans, there are three billion (3,000,000,000) base pairs (letters) in the DNA within each cell.

14. What is DNA?
Among humans, most of the 3 billion bases in the DNA sequence are exactly the same.
Our Human DNA is 99.8% similar to each other, but the 0.2% difference is more than enough to distinguish us from one another.
Human DNA is even 98% similar to chimpanzees.
NO TWO PEOPLE HAVE IDENTICAL DNA*
*except identical twins

15. Stupid Facts: What is DNA?
If two different people started reciting their individual genetic code at a rate of one letter per second, it would take almost eight and a half minutes before they reached a difference.
If unwound and tied together, the strands of DNA in one cell would stretch almost six feet but would be only 50 trillionths of an inch wide.
If all the DNA in your body was put end to end, it would reach to the sun and back over 600 times (100 trillion times six feet divided by 92 million miles).

16. Where is DNA?

17. Where is DNA? DNA is found in the cells in our body. Nucleus
(Brain of the cell)
Mitochondria
(more later)

18. K-Fed sez:
Quiz on Monday.

19. All types of cells in our body contain a copy of the same DNA.*
Where is DNA?
All types of cells in our body contain a copy of the same DNA.*
Some cells important to forensic science are:
White Blood Cell
*Sperm Cell
Cheek Cell

20. DNA in the nucleus is packaged into Chromosomes.
Where is DNA?
DNA in the nucleus is packaged into Chromosomes.

21. There are 46 chromosomes in each cell.
Where is DNA?
Chromosomes
come in pairs
(one from Mother)
(one from Father)
There are 46 chromosomes in each cell.
(23 pairs)

22. DNA can be recovered from any substance that contains cells.
Where is DNA?
What are sources of DNA at a crime scene?
DNA can be recovered from any substance that contains cells.
Blood
Semen
Saliva
Tissue
Bone
Teeth
Hair
Maggot Crops

23. Where is DNA?
Maggot Crop

24. How does DNA differ among Humans?

25. There are several ways the sequence can be different.
How does DNA differ among humans?
DNA is a sequence of 4 possible letters A G C T
Of the 3 billion letters, 99.8% of the sequence in all humans is identical.
There are several ways the sequence can be different. 

26. One of the bases (letters) can be different.
How does DNA differ among humans?
One of the bases (letters) can be different.
Person 1 AGCTAGATCGTTATTCCGAG
Person 2 AGCTAGATCGTCATTCCGAG

27. Bases (letters) can be added or removed.
How does DNA differ among humans?
Bases (letters) can be added or removed.
Person 1 AGCTAGATCGTTATTCCGAG
Person 2 AGCTAGATCGTATTCCGAG
Person 3 AGCTAGATCGTTTATTCCGAG
Person 4 AGCTCCGAG

28. Bases (letters) can be added or removed.
How does DNA differ among humans?
Bases (letters) can be added or removed.
Person 1 AGCTAGATCGTTATTCCGAG
Person 2 AGCTAGATCGTATTCCGAG
Person 3 AGCTAGATCGTTTATTCCGAG
Person 4 AGCTCCGAG

29. Regions of DNA can be repeated a different # of times.
How does DNA differ among humans?
Regions of DNA can be repeated a different # of times.
Person 1 ..GCCAGCTAGCTAGCTAGCTAGCTAGCTTTCAT..

30. Regions of DNA can be repeated a different # of times.
How does DNA differ among humans?
Regions of DNA can be repeated a different # of times.
Person 1 ..GCCAGCTAGCTAGCTAGCTAGCTAGCTTTCAT..
Person 2 ..GCCAGCTAGCTAGCTAGCTAGCTTTCAT..
Person 3 ..GCCAGCTAGCTAGCTAGCTAGCTAGCTAGCTT..