Download GEL ELECTROPHORESIS LAB READING: Read the explanation of

GEL ELECTROPHORESIS LAB
READING:
Read the explanation of Gel Electrophoresis.
Explain the technology of gel electrophoresis?
BACKGROUND.
What is Gel Electrophoresis used for?
What is a DNA fingerprint?
What does CODIS look at?
PROBLEM:
Purpose/ Prediction: Explain how comparing DNA fingerprints can help to identify
a person who has committed a crime?
Hypothesis: (this answers the purpose)
EXPLORE:
Materials:
PROCEDURE:
DATA: In the table below record the estimated length in base pairs (bp) of the DNA
fragments found in the samples from the victim, the suspects, and the evidence. Estimate
the number of base pairs by comparing each band to the marker DNA bands.
Band Marker DNA
length bp
1
2
3
4
5
6
23,130
9,416
6,557
4,361
2,322
2,027
Victim
DNA
bp
?
?
?
Suspect 1
DNA bp
Suspect 2
DNA bp
Evidence
DNA bp
9,416
?
?
?
?
?
?
?
?
?
?
Analyze and Conclude:
1. EVALUATE Does the DNA found on the hair match suspect 1 or suspect 2? Explain
how you know.
2. ANALYZE Why do a series of bands appear on the gel?
3. IDENTIFY CAUSE Why is the largest DNA fragment band found closest to the well in
which it was placed?
4. INFER What is true of the DNA fragment band closest to the positive end of the gel?
5. PREDICT What would happen if the electrodes were plugged into the wrong
outlets?
6. APPLY Do you think DNA fingerprinting is more conclusive when proving a person’s
innocence or their guilt?
Gel electrophoresis is a procedure that separates molecules on the basis of
their rate of movement through a gel under the influence of an electrical
field. The direction of movement is affected by the charge of the molecules,
and the rate of movement is affected by their size and shape, the density of
the gel, and the strength of the electrical
field.
DNA is a negatively charged molecule, so
it will move toward the positive pole of the
gel when a current is applied. When DNA
has been cut by restriction enzymes, the
different-sized fragments will migrate at
different rates. Because the smallest
fragments move the most quickly, they
will migrate the farthest during the time
the current is on. Keep in mind that the
length
of
each
fragm
ent is
meas
ured
in
numb
er of
DNA
base
pairs.
Procedures:
1. Put DNA strands into the different wells in the Gel.
2.