Download Biotechnology

Code of Life Topic 5
Genetic analyses &
Genetic Engineering
Genetic analyses & engineering
• What are these?
• What are the uses?
• What do they start with?
Isolating the gene
• 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
EcoR1 recognizes:
GAATTC
CTTAAG
The enzyme cuts it:
G
AATTC
CTTAA
G
Which DNA segments are used?
• Short tandem repeats (STRs) are short
sequences repeated multiple times in a
row (more or less for different people)
• Good for “fingerprinting”: A total of 13
different STR sites is enough for an
individual profile
Which DNA segments are used?
• Single nucleotide polymorphisms (SNPs) are single
base-pair variations that we can detect (like a
substitution mutation)
• Scientists have a catalog of SNPs that occur in the
human population.
• Restriction fragment length polymorphisms (RFLPs) are
SNPs that change the length of restriction fragments
Which DNA segments are used?
• Restriction Fragment Length
Polymorphisms (RFLPs)
Analyzing the differences
between people
1. Use restriction enzymes to cut the DNA
2. Load the DNA onto agarose gel for gel
electrophoresis (next slide)
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
• This gene is called p53. The mutated version is
linked to colon cancer.
• 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?
Recombinant DNA
• DNA that is combined from two different
organisms.
• One example: To insert genes of an organism
into bacteria to harvest protein for medicine.
• Important players:
–
–
–
–
Gene of interest (i.e. insulin, hGH, etc)
Restriction enzymes
Plasmid
Bacteria
Making
Recombinant DNA
• Plasmids - selfreplicating rings of
DNA containing 2-30
genes, found in
bacterial cells
• Plasmid and gene cut
with same restriction
enzymes
• Plasmid and gene
have complementary
“sticky” ends
Making Recombinant DNA
1.
2.
3.
4.
5.
Cut the gene of interest
using a restriction
enzyme
Cut the plasmid (using
the same enzyme)
Insert gene into the
plasmid
Insert the plasmid into
bacteria
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)