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Lecture 23 DNA
Polymorphisms
Based on Chapter 10
Recombinant DNA Technology
Copyright © 2010 Pearson Education Inc.
1. Questions you should be able to answer
from today’s lecture.
1. What types of DNA polymorphisms are present in the genome?
2. How can DNA polymorphisms be used in genetic analysis and in
disease diagnosis?
3. What is DNA fingerprinting (DNA typing) and how can it be used?
4. How does gene therapy work?
5. How are the techniques used to clone, amplify, and manipulate
DNA applied commercially in the biotechnology industry?
6. How can plants be engineered genetically?
2. Uses of DNA Polymorphisms in Genetic
Analysis
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•
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Genes have historically been used as markers for
genetic mapping experiments.
A DNA polymorphism is two or more alleles at a locus
that vary in nucleotide sequence or number of repeated
nucleotide units (indels).
DNA markers are polymorphisms suitable for mapping,
used in association with gene markers for genetic and
physical mapping of chromosomes.
3. Single Nucleotide Polymorphism (SNPs, “Snips”):
Southern Blot
4. Single Nucleotide Polymorphism (SNPs,
“Snips”): PCR
5. Detection of All SNPs
6. Short Tandem Repeats (STRs) &
Variable Number Tandem Repeats
(VNTRs)
7. DNA Molecular Testing for Human Genetic
Disease Mutations
• DNA testing is increasingly available for
genetic diseases, including:
– Huntington disease.
– Hemophilia.
– Cystic fibrosis.
– Tay–Sachs disease.
– Sickle-cell anemia.
8. Purposes of Human Genetic Testing
Human genetic testing serves three main purposes:
• Prenatal diagnosis - uses amniocentesis or chorionic
villus sampling to assess risk to the fetus of a genetic
disorder
• Newborn screening .- examples of tests for specific
mutations using blood from newborns include:
– Phenylketonuria (PKU).
– Sickle-cell anemia.
– Tay–Sachs disease.
• Carrier (heterozygote) detection - Carrier testing is now
available for many genetic diseases, including:
– Huntington disease.
– Duchenne muscular dystrophy.
– Cystic fibrosis.
9. Examples of DNA Molecular Testing: Testing by
Restriction Fragment Length Polymorphism
11. Examples of DNA Molecular Testing: Testing Using
PCR Approaches
12. Examples of DNA Molecular Testing: DNA
Microarrays in Disease Diagnosis
1. Results given as ratios
2. Images use colors:
Cy3 = Green
Cy5 = red
Yellow
3. Yellow is equal
intensity or no change
in expression
13. DNA Typing
14. Applications of DNA Typing
Examples of DNA typing used to analyze samples include:
• Crime scene invetigation
• Population studies to determine variability in groups of
people.
• Proving horse pedigrees for registration purposes.
• Conservation biology to determine genetic variation in
endangered species.
• Forensic analysis in wildlife
crimes, allowing body parts
of poached animals to be
used as evidence.
• Detection of pathogenic
E. coli strains in foods
• Detection of genetically
modified organisms (GMOs)
in bulk or processed foods