1. DNA Fingerprinting and Gel Electrophoresis Notes
March 1, 2017

2. I contain the code for making enzymes
DNA fingerprints
Made by cutting DNA in very specific places.
How do we cut DNA?
Restriction Enzymes
I contain the code for making enzymes

3. I. DNA Fingerprinting
Because no two individuals have identical DNA, no two individuals will have the same length fragments

4. II. Gel Electrophoresis
A technique used to separate the DNA fragments according to their size
DNA fragments are placed in wells on a sheet of agarose gel
Gel is slightly porous and allows fragments to move through the gel at a rate relative to their size …
Like a plinko board

5. B. An electric current is applied to the sheet
C. DNA is negatively charged and will move in an electric field toward the positive pole
Which size fragments do you expect to move faster through the gel?
Smaller fragments move through the gel at a faster rate compared to the larger pieces

6. DNA bands must be stained to make them visible
D. Bands will be produced on the gelatin where the fragments accumulate
The more fragments that accumulate in one spot, the thicker the line will be in the gel
DNA bands must be stained to make them visible

8. III. Uses for DNA Fingerprinting and Gel Electrophoresis
Used in forensics as a way to match a sample from a crime scene to a suspect’s DNA
Used in paternity cases where the father is unknown
Each fragment in the child’s DNA must match at least one of the parent’s fragments
nimations/content/paternitytesting.html

10. Circle the largest… square the smallest.

11. Who are the parents of baby 1?

12. Who are the parents of baby 2?

13. Who are the parents of baby 3?

14. Genotyping
If a person was homozygous for a trait, the DNA would be cut by the same restriction enzyme in the same place because alleles are the same
Fragments would be at the same point when run through a gel electrophoresis
Allele from Mom
Allele from Dad

15. If a person was heterozygous for a trait, the DNA would be cut by the same restriction enzyme in different places because the alleles are different
Fragments would not be at the same point in the gel electrophoresis
Allele from Mom
Allele from Dad

16. YOUR TURN: Label the fragments by size (1 is largest)
Dominant Allele from Mom
Recessive Allele from Dad

17. In the first lane, sketch a heterozygous genotype 1
Dominant Allele from Mom
Recessive Allele from Dad
In the first lane, sketch a heterozygous genotype 1 2 3 4 5
Thicker because there are 2 sized “5” pieces

18. In the second lane, sketch a HOMOZYGOUS DOMINANT genotype 1
Dominant Allele from Mom
Recessive Allele from Dad x2
In the second lane, sketch a HOMOZYGOUS DOMINANT genotype 1 2 3 4 5
Thicker because there are 2 sized “5” pieces

19. In the third lane, sketch a HOMOZYGOUS RECESSIVE genotype 1
Dominant Allele from Mom
Recessive Allele from Dad x2
In the third lane, sketch a HOMOZYGOUS RECESSIVE genotype 1 2 3 4 5
Thicker because there are 2 sized “5” pieces

20. Recombinant DNA intro

21. Recombinant DNA
Recombinant DNA contains DNA from 2 or more different sources.
So how does DNA get from one species to another?
Vector: something used to transfer DNA from one organism to another
Microinjection
Gene Gun
Virus
Bacteria Plasmid

22. Transgenics
Genetic engineering makes it possible to transfer DNA sequences from one organism to another
REMEMBER- DNA is universal
A gene taken from one species can be replicated in another species.

23. So how do I take a gene from one organism and put it into another?
We have to cut it using a Restriction Enzyme