Download 242413_Fx_DNA_Fingerprinting_Lab

Name:__________________________
Forensic Science
DNA Fingerprinting
1.15.14
Go to Mr. Mason's website and follow the appropriate links to answer the
following questions. You’ll be bouncing back and forth between pages 5 and 6 of
my links. Needless to say, all of these will need to be answered on a separate
piece of paper.
Genetics - GSLC Gel Electrophoresis
1. What is the purpose of gel electrophoresis?
2. What must be added to move the DNA through the gel?
3. Why do different strands of DNA move at different rates through the gel?
4.
5.
6.
7.
Explain to the best of your ability!
What is the purpose of the “comb” in setting up a gel?
What is the purpose of the loading buffer?
Why do we use the DNA size standard?
What were the approximate sizes of the DNA fragments in the sample
you ran?
Genetics - PBS Create a DNA Fingerprint
1. What is the purpose of restriction enzymes in creating a DNA fingerprint?
2. Which end of the gel does the DNA move towards? Why?
3. What's with the nylon membrane? What purpose does it serve?
4. What’s different about the DNA fragments in the probe?
5. Who was the bratty sister who took the lollipop?
Genetics - Gene Almanac
1. In gel electrophoresis, why is the gel submerged in a salt solution?
2. Which part of DNA is the source of its negative charge? Why does this
matter?
3. Watch the animations of the DNA moving through the gel matrix a few
times. Breathe…relax…ahhh…… 
4. What is the purpose of adding ethidium bromide to the DNA?
Genetics - DNALC DNA Fingerprinting
1. What are repeat polymorphisms? Where are they found? (Specifically,
are they found as part of genes, or are they found in non-coding DNA?)
2. What is the difference between a VNTR and an STR?
3. If you inherited a chromosome from your father that had 7 repeats at a
certain locus (location of a specific gene) and a chromosome from your
mother that had 12 repeats, what would your genotype be for this specific
repeating sequence?
Genetics – Today’s DNA Profile
1. How many STRs are analyzed by the FBI (which thus sets the standard for
all other law enforcement agencies)? Note: add 1 to the number given for
the sex marker
2. When reading the chart resulting from the laser analysis of the STRs,
what does it indicate about the alleles when an individual has two peaks
at a specific locus? (Run the sample through the machine, then proceed
to where it focuses on the blue line. Read each page, but it takes quite a
few pages to get to this point.)
3. The next number of pages gets into a discussion of the Hardy-Weinberg
equation, which basically explains how allele (different versions of genes)
frequency can be predicted in a population. If you take AP Biology or a
college-level Biology class you will need to learn this, but for the time
being you can skip forward to the page after the flashing question mark.
Using the Hardy-Weinberg equation provided, what is the probability of a
Hispanic individual being heterozygous for D8S1179 for alleles 9 and 13?
(Note: This answer is not given to you by the site – you need to use the
table shown and enter the given numbers into the equation 2pq where p
and q are the values given by the table for the relevant alleles for that
ethnic group. Yes, a simple calculation is needed here, and yes, there is
only one right answer.)
4. Remember the product rule from one of our first assignments last
semester? That’s the basic gist of how STRs are used. If you know the
probability of an allele combination for each of the STRs analyzed, you
can then multiply those frequencies together to determine the odds of a
random match in a given population. According to the site, how likely is it
for two people to randomly have the same STR profile? (provide the
actual number given)
Final Question
Based on the information from the first three websites you visited, write a
simplified, bulleted list of instructions for making a standard DNA fingerprint.
Use the information given, but clarify it and use your own words. (3 points –
you cannot get an A on this assignment if this part is not complete.)