Download Use of DNA Technology:

USE OF DNA
TECHNOLOGY:
DNA PROFILING
USES OF DNA TECHNOLOGY
• DNA Profiling
• Parentage Testing
• Genealogy
• Genetic Screening
• Genetically Modified Organisms
DNA PROFILING
• Method to identify an individual based upon their
DNA
• Used in:
• Criminal investigations
• Parentage Testing
UNDERLYING PRINCIPLE
• Over 99.9% of our DNA is identical across all
people
• BUT this means some is different
UNDERLYING PRINCIPLE
• In our different DNA:
• Variable number tandem repeats (VNTRs)
• DNA made up of repetitive sequences that can
be found in different numbers for different
people
• STRs: short tandem repeats (2-5nt long)
• LTRs: long tandem repeats
UNDERLYING PRINCIPLE
UNDERLYING PRINCIPLE
• VNTRs:
• Are genetic…
• The number of repeats in any given VNTR
would have been passed down from a parent
UNDERLYING PRINCIPLE
• VNTRs:
• Are very numerous in our genome
• Take home message:
• The number of repeats in each VNTR is unique
amongst individuals (unless identical twins)
• You share roughly 50% of these repeats in
common with your parents and siblings
DNA PROFILING OVERVIEW
• Uses PCR to amplify VNTRs and then gel
electrophoresis to visualize the DNA fragments
created
• This creates a unique DNA profile for each
person
DNA PROFILING: PCR
• Primers are designed to “bookend” a VNTR of
interest
• Primers need to anneal to a conserved region
of DNA that is identical to each person
UNDERLYING PRINCIPLE
DNA PROFILING: PCR
• Primers are designed to “bookend” a VNTR of
interest
• Primers need to anneal to a conserved region of
DNA that is identical to each person
• PCR will therefore give different fragments lengths
based on how many repeats a person has
DNA PROFILING: GEL ELECTROPHORESIS
• After the PCR, DNA is run on a gel to visualize
the lengths of the DNA products
UNDERLYING PRINCIPLE
DNA PROFILING
• To accurately identify a person and reduce false
positives:
• U.S. examines 13 separate VNTRs
• UK has a system with 11 VNTRs
• Both of these have VNTRs that are found on different
chromosomes
• Think “Law of Independent Assortment”
DNA PROFILING
• Criminal Investigations:
• Identifying who an
unknown DNA sample
belongs to
DNA PROFILING
• Paternity Testing:
• Identifying who the
father/parents of a
child are