code of life topic 5 genetic analyses & genetic engineering
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Code of Life Topic 5Genetic analyses &
Genetic engineering
(An incomplete) timeline of genetics
1944 Avery
1952
1958
1968
1953 1972
1973
1975-77
1983
1990
Applications• Genetic analyses and engineering
Isolating genes• Use special proteins to cut
the DNA strand at specific places
• Restriction enzymes:– Target very specific base
sequences– Are found in more than 100
different varieties– Are used in nature to protect
bacteria from foreign invaders
Restriction Enzymes
• Each restriction enzyme recognizes a very specific nucleotide sequence
Example: EcoR1 recognizesGAATTC CTTAAG
The enzyme cuts it:G AATTC
CTTAA G
Which DNA segments are used?
• Short tandem repeats (STRs)
• Good for “fingerprinting”
Which DNA segments are used?
• Single nucleotide polymorphisms (SNPs) • Catalog of human SNPs
• Restriction fragment length polymorphisms (RFLPs) are SNPs that change the length of restriction fragments
Restriction Fragment Length Polymorphisms (RFLPs)
Analyzing the differences between people
STEPS
1.Use restriction enzymes to cut the DNA
2.Load the DNA onto agarose gel for gel electrophoresis
3.Analyze the banding pattern
Gel Electrophoresis• Separates DNA fragments by size using
electric current
Gel Electrophoresis• Larger fragments move more slowly
• Results in bands of DNA fragments of different lengths
DNA Analysis• Useful for:
– Forensic science (crime scene “fingerprints”)– Determining paternity – Looking at disease risk
Lab!
• We will be conducting a lab to determine whether or not a young woman carries one or two copies of a mutant gene
• The mutated version of the gene is responsible for Tay Sach’s disease.
• How do you think we will go about this?– RFLPs and gel electrophoresis
• Besides the young woman’s, whose DNA should we also look at?
To test or not to test?
• PGD
• During pregnancy
• After birth/during childhood
• As an adult
• Bioethics
Genetic engineering
Changing the DNA of organisms
Recombinant DNA• DNA that is combined from two different
organisms.• Common/first example: insertion of a gene from
an animal into bacteria to harvest protein Important players:– Gene of interest (i.e. insulin, hGH, etc)– Restriction enzymes– Plasmid– Host bacteria
Making Recombinant DNA
• Plasmids - self-replicating rings of DNA containing 2-30 genes, found in bacterial cells
• Plasmid and gene of interest cut with same restriction enzymes
• Plasmid and gene have complementary “sticky” ends
Making Recombinant DNA
1. Cut the gene of interest using a restriction enzyme
2. Cut the plasmid (using the same enzyme)
3. Insert gene into the plasmid
4. Insert the plasmid into bacteria
5. Grow bacteria and harvest the protein
How could you tell if the transformation really took place?
Genetic Engineering Applications
• Pest-resistant crops (Bt toxin)
Genetic Engineering Applications
• Herbicide-resistant crops • Fast-growing fish• Green-glowing
aquarium fish (jellyfish genes)
• Bacterial drug production (insulin, hGH)
Diagram on p. 14 in your packet (for #1-4)
Diagram on p. 15 in your packet (for #6-7)
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