1. Date: January 31th, 2017
Aim #46: How do scientists identify people using DNA Fingerprinting?
HW:
Daily Review of Class Notes
Biotechnology Textbook Homework due Friday 2/3
Quiz Monday 
Do Now:
Please turn-in “Serving Food with A Side of Hormones” worksheet.

2. Aim #46: How do scientists identify people using DNA Fingerprinting?

3. 1) Why do we Fingerprint?
So we can identify people

4. 2) Why is DNA used to identify people?
People have different DNA base sequences, therefore
each individual will have a different DNA fingerprint.

5. 3) Genetic Markers: ATTGCCTAGG - Individual 1
ATTGCCATGG - Individual 2
Are particular stretches of DNA that are variable (different)
among individuals.
Our noncoding regions are highly variable from one
individual to another and serve as good genetic
markers to be used for DNA fingerprinting.

6. 4) How do scientists make a DNA Fingerprint?
Investigators need to find
some DNA of the perpetrator.
a) Where can the investigators find the DNA?
Blood
Hair
Nails
Skin

7. b) What if you only find very little DNA?
Polymerase Chain Reaction: PCR
The sample of DNA is then amplified (multiplied) using a process called Polymerase Chain Reaction (PCR).

8. PCR Animation

9. 5) Gel Electrophoresis Amplified DNA is treated
with specific restriction
enzymes.
2) DNA segments are loaded
into wells in a porous gel.
3) Electric current is passed
through the gel making one
side of the gel + charged and
one side – charged.

10. 5) Gel Electrophoresis DNA is negatively charged
& moves through the gel to
the positive side.
5) Smaller segments move
faster & farther than the
larger segments.

11. 5) Gel Electrophoresis 6) The gel is then stained
so we can see the DNA
banding patterns.
Result: The smaller
segments of DNA are found
closer to the positive end
than the larger segments.
**Separates DNA segments
according to SIZE.

12. - + Gel Electrophoresis __ __ __ __ __ __ __ __ __ __
DNA Suspect A Suspect B Suspect C
from CS
__ __ __ __
__ __
__ __ __ __ +

13. DNA Fingerprint Questions:
What is the charge of DNA?
Where would we find the smallest DNA fragments,
closer to the + end or the – end?
Why do we get different banding patterns for each
individual?
4) Which suspect was at the crime scene?