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The Case of the Missing Strawberries:
RFLP Analysis
Microsoft Clipart
picture of strawberries
Heidi Sleister
Assoc. Professor of Biology
Drake University
1344 27th Street
Des Moines, Iowa 50311
[email protected]
Case Background
• Problem:
– Strawberries are missing from the school garden.
– A search led to 5 people with strawberries.
– Do any of these strawberries match the strawberries
from the garden?
Heidi Sleister
Chromosomes are made of DNA and
are found in the nucleus of a cell
Insert a picture which
shows the relationship
of DNA, chromosomes,
and a cell.
Heidi Sleister
DNA has a double-stranded helical structure
Insert a picture which
shows the structure of
DNA (double helix,
paired nitrogenous bases
(G-C, A-T)).
Heidi Sleister
Solving the Case
• Experimental Strategy:
– Isolate DNA from strawberries
– Use RFLP analysis to compare garden strawberry plant
DNA to the “suspect” strawberries.
Heidi Sleister
Applications of RFLP Analysis
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Disease diagnosis
Genetic mapping
Forensic science
Genetically modified organisms
Paternity testing
Personal identification
Plant breeding
Characterization of genetic diversity
Species identification
Heidi Sleister
Restriction endonucleases cut specific
sequences of DNA and produce DNA fragments
EcoRI
restriction site
ACCATAAGAATTCAATCC
TGGTATTCTTAAGTTAGG
ACCATAAG
TGGTATTCTTAA
AATTCAATCC
GTTAGG
Fragment 1
Fragment 2
Heidi Sleister
Different sizes of DNA fragments can be
distinguished by gel electrophoresis
Insert picture of gel
electrophoresis chamber
and gel.
Heidi Sleister
Restriction fragment length polymorphisms
(RFLPs)
Allele 1
Allele 2
-------GAATTC-------------------
Allele 1
EcoRI site
Gel electrophoresis of
allele 1 and allele 2 DNAs
digested with EcoRI.
Marker
Allele 1 and Allele 2 differ by only a single basepair
which is located within the EcoRI restriction site.
-------CTTAAG------------------Fragment A2-1
Fragment A1-1
Fragment A1-2
Fragment A1-2
No EcoRI site
-------GACTTC------------------Allele 2
-------CTGAAG-------------------
Fragment A1-1
Fragment A2-1
Heidi Sleister