Name: _____________________________________ Period: _____
DNA Fingerprinting and Restriction Enzymes
Humans have DNA packaged into 23 pairs of chromosomes. Most of this DNA is identical
between individuals, but there are small sequence differences called polymorphisms. These
polymorphisms include single base pair changes and repetitive DNA elements. Analyzing
several polymorphisms within a person’s genome generates a unique DNA fingerprint.
The best known application of DNA fingerprinting is in forensic science. DNA fingerprinting
techniques are used to analyze blood, tissue, and other body fluids from crime scenes. DNA is
extracted from these samples and compared to the DNA fingerprints of suspects. DNA
fingerprinting can also be used to match DNA samples to known sequences of different species.
A technique called polymerase chain reaction (PCR) is used to amplify the sequences of DNA.
Analysis also involves treating DNA with special enzymes called restriction enzymes, which
act like molecular scissors to cut DNA at specific sites. Digestion by these enzymes will produce
fragments of varying lengths.
If a restriction site occurs within the sample sequence, the probe will reveal multiple bands of DNA that have
different sizes. This technique is called restriction fragment length polymorphism (RFLP).
The samples are transferred with a micropipet to agarose gel. When electricity is applied, the fragments will
move through the gel. Shorter fragments will move farther. This technique, called gel electrophoresis,
separates DNA fragments by size.
___ PCR amplification
___DNA extracted from tissue.
___DNA fragments move across gel
___DNA sample loaded into wells
___DNA stained with fluorescent
dye
___Electricity applied to gel
The HaeIII is a restriction enzyme that attaches at the restriction site GGCC and cuts
between the second G and the first C ( GG / CC ).
The DNA fragments below match one of 6 different species of penguin. Mark the sites
in each fragment where the HaeIII enzyme cuts and then fill in the chart to identify
each penguin sample.
(1) CGATAGCTCGATAGCCCGCGGATGTCTGTGCTGGGCCATTACCCCGATGATGCCT
(2)
CGATAGCTCGATAGGCCGCGGATGTCTGTGCTGCGCCTGGCCATTACCCCGATGATGCCT
(3) CCGGCGCCGGCCGATAGCCCGCGGATGTTGCTGGGCCATTACCCCGATGATGCCT
(4) CCGGGCCCTCGATAGCCCGCGGATGTCTTGCTGGGCCATTACCCCGATGATGCCT
(5)
CCGGCGCCGCCGATTAGCCCGCGGATGTTTGCTGGCCCCTACCGGCCTCT
(6) CCGGGCGCCGCCGATAGCCCGCGGATGTTTGCTGGCCCATTACCTACCGGCCTCT
Fragment
Length
Sample
1
Sample
2
Sample
3
Sample
4
Sample
5
Sample
6
Humbol
dt
Galapag
os
African
Adelie
Emperor
35 bp
30 bp
25 bp
20 bp
15 bp
10 bp
5 bp
Sample 1: _________________________
Sample 2: _________________________
Sample 3: _________________________
Sample 4: _________________________
Sample 5: _________________________
Sample 6: _________________________
Learn more about penguins at : https://seaworld.org/animals/all-about/penguins/appendix/
Little
Blue