Transcript Understanding Our Environment - McGraw Hill Higher Education

Gene Technology
Chapter 9
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Outline
•
•
•
•
•
•
•
•
Restriction Enzymes
Genetic Engineering Experiments
Polymerase Chain Reaction
DNA Fingerprinting
Genetic Engineering and Medicine
Genetic Engineering of Crop Plants
Genetic Engineering of Farm Animals
Cloning
 Ethical Issues
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Scientific Revolution
•
Genetic Engineering refers to the process of
moving genes from one organism to another.
 Having major impact on medicine and
agriculture.
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Restriction Enzymes
•
Restriction enzymes that bind to specific
short sequences (typically 4 to 6 nucleotides)
of DNA.
 Restriction enzymes make their incisions
so that two single-stranded ends are
complementary in sequence (sticky ends).
- Can pair with any other DNA fragment
cut by same enzyme.
 Joined by DNA ligase.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Restriction Enzymes
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Genetic Engineering Experiment
•
•
•
•
Cleaving DNA To Produce Fragments
 Can sort using electrophoresis.
Producing Recombinant DNA
 Insert fragments into plasmids or viral DNA.
Cloning
 Plasmids or viruses serve as vectors.
Screening
 Locate specific sequences.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Screening
•
•
Preliminary Screening
 Eliminate from clone library any clones not
containing vectors.
Finding Gene of Interest
 Use cloned genes from base pairs with
complementary sequences on another
nucleic acid (Probe).
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Other Genetic Techniques
•
Polymerase Chain Reaction (PCR)
Copyright © McGraw-Hill Companies
Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Other Genetic Techniques
•
Formation of cDNA
 Entire gene is transcribed by RNA
polymerase forming primary transcript.
- Introns must be cut out, and remaining
fragments stitched together to form
processed mRNA.
 Cytoplasmic mRNA has only exons.
Reverse transcriptase is used to make
an DNA version of isolated mRNA
(cDNA).
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Other Genetic Techniques
•
DNA Fingerprinting
 Using DNA probes to characterize DNA
isolated from an individual.
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Genetic Engineering and Medicine
•
Diabetes is a condition where body is unable
to control levels of sugar in the blood
because a critical protein, insulin, cannot be
made.
 Genes encoding many medically important
proteins are now introduced into bacteria.
- Insulin
- Anticoagulants
- Factor VIII
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Genetic Engineering and Medicine
•
•
Piggyback Vaccines
 Traditionally, vaccines were made by killing
the disease agent. Now a modified virus
displays piggybacked surface proteins, to
which immune system makes antibodies.
Gene Therapy
 One way to cure many genetic diseases is
to give the affected person a working copy
of the defective gene.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Piggyback Vaccine for Herpes Simplex
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Genetic Engineering of Crop Plants
•
•
•
Pest Resistance
 Reduce use of chemical pesticides.
Herbicide Resistance
 Lowers cost of producing crop.
 Reduced plowing conserves topsoil.
More Nutritious Crops
 Golden Rice
- Iron and Vitamin A
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Transgenic Golden Rice
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Genetic Engineering of Crop Plants
•
Potential Risks: Is Eating Them Dangerous?
 Roundup Resistant soybeans:
- Inhibits Aromatic Amino Acid production
to make crop easier to grow.
 Humans don’t make any
- Changes nutritional character to improve
nutrition.
 Potential allergies
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Genetic Engineering of Crop Plants
•
Potential Risks: Harmful to the Environment?
 Bt corn was genetically engineered to
contain insect-killing toxin to combat cornborers, but also killed butterflies.
- Must weigh pesticide-induced losses to
genetically-modified losses.
 Introduced genes may pass to wild
relatives.
- Gene flow occurs naturally.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Genetic Engineering of Farm Animals
•
1994 - Monsanto received federal approval
to make its recombinant bovine somatotropin
(BST) commercially available to dairy
farmers.
 Consumers worry about transfer through
cow’s milk.
- This transfer does not occur, and effects
to humans would be negligible, if any.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Cloning
•
Dolly
 Mammary cells and egg cells surgically
combined in January 1996.
- Mammary cells inserted inside the
covering around the egg cell.
 Brief electrical shock applied.
 29 dividing embryos transplanted
into surrogate mother sheep, and
on July 5, 1997, one sheep gave
birth to a lamb.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Ethical Issues
•
Fear of human cloning at the heart of ethical
dilemmas (Technical reasons should not
prove an overwhelming obstacle).
 Value of Gene Therapy vs:
- Personal identity issues.
- Increased genetic uniformity may cause
future disease problems.
 Inability to adapt to changing
environmental conditions.
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Review
•
•
•
•
•
•
•
•
Restriction Enzymes
Genetic Engineering Experiments
Polymerase Chain Reaction
DNA Fingerprinting
Genetic Engineering and Medicine
Genetic Engineering of Crop Plants
Genetic Engineering of Farm Animals
Cloning
 Ethical Issues
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies
Copyright © McGraw-Hill Companies Permission required for reproduction or display
Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies