Finish Part A of your Gel Electrophoresis Lab.
1. Make sure you have everything done in red to the left of the
screen. (Grade for Part A)
2. There are lab pages at your tables to help you finish.
3. If you were not here for the lab, come see me to set up a time
to complete it outside of class time.
IN ABOUT FIFTEEN MINUTES….
1. I will begin the pre-lab for Part B- DNA Fingerprinting.
2. Your DNA/protein synthesis test has been pushed to next
Thursday 2/23 because Part B will take up Friday and
Tuesday….review game Wednesday….
DNA FINGERPRINTING:
CSI
Lab 6: Molecular Biology
Part B
Investigators were called to the scene of a homicide.
Found at the scene was a large amount of blood.
Blood typing revealed that not only was the blood of
the victim present at the scene, BUT also blood from
another person…..assumed to be the guilty party.
Originally there were four suspects…….
Two suspects had alibis that checked out.
SUSPECT #1
SUSPECT #2
SUSPECT #3
At the time of the murder,
suspect # 3 was seen
being escorted out of a
local Taco Bueno with two
other trouble-makers.
Apparently making fun of
fellow Bueno patrons.
That’s no bueno.
SUSPECT #4
At the time of the
murder, suspect #4
was already in
county, being held
for his involvement
in a karaoke/brawl
fiasco. (It’s always
the quiet ones…)
Blood samples from the remaining two suspects were drawn
under court order and were found to be of the same blood
type as the mystery blood found at the crime scene.
The police have turned to you and your fellow lab
technicians to employ the process of DNA fingerprinting in
building a case against one of the suspects.
“Kill everybody”
..enough said…
And how many
times have we
heard,
“I will stab you…”
Let’s face
it…..he just
looks guilty.
SUSPECT #1
SUSPECT #2
With the exception of (young) identical twins, no two
people have the same DNA sequence.
Introns and epi-genetics (years of environmental
effects and amount of mitosis trials) cause great
differences between individual’s genes.
Because of these things, people’s genes are different
sizes (the more base pairs, the greater the Molecular
Weight of an individual gene).
Before DNA fingerprinting can be completed, the
genes of the individual’s DNA are cleaved (cut) with
restriction enzymes
For our lab, we have the cleaved genes from:
-the crime scene (mystery person)
-Suspect #1 (we will call them “Chris”)
-Suspect #2 (we will call them “Amazing”)
-We will also run what is called a “Standard DNA Marker”
Because the genes are different sizes (amts of base pairs), they
will move at faster and slower paces, showing different bands for
each gene.
What do you know about the genes that move further away from
the wells?
1
2
3
4
5
6
7
If lane six shows the crime
What do you notice that is different this time?
DNA is a slightly negatively charged molecule, so it
will travel toward the positive end.
So make sure your wells are next to the negative
side of the container before you begin.
-
Lane #1
Lane #2
Lane #3
Lane #4
DNA
marker
standard
Crime
Scene
DNA
Sample
Suspect 1
Suspect 2
“Chris”
“Chaumont”
This is a standard marker.
It shows different base pair
sizes (sizes of genes), so
that you can approximate
the base pair sizes of the
bands from the suspects.
+
1. You can load the wells tomorrow dry or submarine.
2. You will pour the buffer solution the same as yesterday
3. Each DNA sample contains the genes and a dye (the dye is NOT used to stain
the DNA, but it is lighter in mass than any of the DNA genes….so it is used as
a marker to know when to turn off the electrodes. It will show as a blue line.
4. You will not see the DNA bands….just the blue line.
5. Tomorrow we will load and run our gels and store them in the fridge over the
weekend.
6. On Tuesday we will stain our gels to show the DNA bands and
●measure the bands for base size (comparing it to the standard)
●measure distance travelled in mm
●and to see which suspect matches the crime scene DNA
1. First make a Table of Contents entry and write the
title of this lab on the page you are using for Part B.
2. Write the purpose for this lab…
3. Create four Data Tables like the one found at your
desk…one for each sample, so label them accordingly- ex.
(one should be titled “Standard”, one titled “ Crime Scene”
I will give you the Length (base pair size) for each fragment in your
Standard’s Table.
Lab 6, DNA Fingerprinting Part B
Purpose: Identify the guilty suspect in a criminal
investigation by reading DNA fingerprinting. Determine
the size of unknown DNA molecules.
Fragment
1 (top-closest to well)
2
3
4
5
6
7
8
9
10
11
12
13
Distance Migrated from well (mm)
Length of gene (approx # of base pairs)