Chapter 13
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Transcript of Chapter 13
CHAPTER 13Biotechnology
TRADITIONAL APPLICATIONS
Biotechnology is applied biology Modern focus on genetic engineering,
recombinant DNA technology, cloning, and analysis of biomolecules
Traditional (historical) applications of biotechnology date back to over 10,000 years ago
Use of yeast to produce beer and wine in Egypt and Near East
Selective breeding of plants and animals
GENETIC ENGINEERING
Genetic engineering refers to the modification of genetic material to achieve specific goals
GENETIC ENGINEERING
Major goals of genetic engineering Learn more about cellular processes,
including inheritance and gene expression
Provide better understanding and treatment of diseases, particularly genetic disorders
Generate economic and social benefits through production of valuable biomolecules (vaccines, and hormones)
Improved plants and animals for agriculture
RECOMBINANT DNA
Genetic engineering utilizes recombinant DNA technology
Splicing together of genes or portions of genes from different organisms
Recombinant DNA can be transferred to plants and animals
Modified animals are called transgenic or genetically modified organisms (GMOs)
Most modern biotechnology includes manipulation of DNA
Many natural processes recombine DNA
TRANSFORMATION
Bacteria can naturally take up DNA from the environment (transformation) and integrate the new genes into the genome (recombination)
VIRAL TRANSFER OF DNA
Viral life cycle1. Viral particle invades host cell2. Viral DNA is replicated3. Viral protein molecules are synthesized4. Offspring viruses are assembled and
break out of the host cell
BIOTECHNOLOGY AND FORENSICS
Forensics is the science of criminal and victim identification
DNA technology has allowed forensic science to identify victims and criminals from trace biological samples Genetic sequences of any human
individual are unique DNA analysis reveals patterns that
identify people with a high degree of accuracy
POLYMERASE CHAIN REACTION
Forensic technicians typically have very little DNA with which to perform analyses
Polymerase Chain Reaction (PCR) produces virtually unlimited copies of a very small DNA sample
POLYMERASE CHAIN REACTION
Forensic scientists focus on short tandem repeats (STRs) found within the human genome
STRs are repeated sequences of DNA within the chromosomes that do not code for proteins
STRs vary greatly between different human individuals
A match of 13 different STRs between suspect and crime scene DNA virtually proves the suspect was at the crime scene
GEL ELECTROPHORESIS
Is a technique used to spread out different-length DNA fragments in a mixture
Distinctive pattern of STR numbers and lengths are fairly unique to a specific individual (forming a DNA fingerprint)
DNA fingerprint from crime scene can be matched with DNA fingerprint of suspect
BIOTECHNOLOGY AND AGRICULTURE
At least three-quarters of corn, cotton, and soybeans grown in the US are genetically modified
MANY CROPS ARE GENETICALLY MODIFIED
Crop plants are commonly modified to improve insect and herbicide resistance
Herbicide resistant crops withstand applications of weed-killing chemicals
Bt gene (from Bacillus thuringiensis bacterium) can be inserted into plants to produce insect-killing protein in crops
CLONING OF THE DESIRED GENE
Modifying a plant genetically begins with gene cloning
1. Desired gene is first isolated from organism containing it Desired gene may alternately be
synthesized in the laboratory
2. Gene is next cloned by inserting it into a plasmid which replicates itself autonomously in bacterial cells
3. Transfect the host organism.
GM PLANTS AND MEDICINES
Medically useful genes can be inserted into plants—examples:
Potatoes have been engineered to produce harmless hepatitis B virus and E. coli proteins, stimulating an immune response when eaten
Plants could be engineered to produce human antibodies, conferring passive immunity to microbial infection merely by eating the plant
GM ANIMALS
Transgenic (Genetically Modified) animals can be engineered by incorporating genes into chromosomes of a fertilized egg
Healthy transgenic animals are difficult to engineer
Animals like sheep might be engineered to produce more wool, cattle to produce more proteins in their milk
THE HUMAN GENOME PROJECT
Findings Human genome contains ~25,000 genes New genes, including many disease-
associated genes have been discovered Has determined the nucleotide sequence of
all the DNA in our entire set of genes, called the human genome
The genes comprise 2% of all the DNA
THE HUMAN GENOME PROJECT
Applications Improved diagnosis, treatment and cures of
genetic disorders or predispositions Comparison of our genome to those of
other species will clarify the genetic differences that help to make us human
DIAGNOSIS OF INHERITED DISORDERS
Potential parents can learn if they are carriers of a heritable disorder through testing
Alleles for defective genes differ from normal, functional genes in nucleotide sequence
DISEASE TREATMENT
Treatments using DNA technology Tailored medical care Recombinant DNA to make proteins Replacing defective genes to possibly
cure a disorder – Gene Therapy Curing AIDS patients by eliminating
the receptor site for the virus Remove stem cells from red bone
marrow, genetically repair the cells, and replace
ETHICAL ISSUES OF BIOTECHNOLOGY
GM Organisms in Agriculture The goal of breeding or genetically
modifying plants or livestock is to make them more productive, efficient, or useful
Genetic modification differs from selective breeding (“traditional biotechnology”)
Genetic engineering is much more rapid Genetic engineering can transfer genes
between species Genetic engineering can produce new genes
never seen before on Earth
GM ORGANISMS IN AGRICULTURE
Benefits of genetically modified plants Transgenic crops decrease applications of
pesticides, saving fuel, labor, and money GM plants can be sold at a lower price due to
farm savings Genetically engineered crops can deliver
greater amounts of vitamins e.g. “golden rice” which
produces vitamin A
SCIENTIFIC OBJECTIONS TO GMOS
Safety issues from eating GMOs Could ingestion of Bt protein in insect-
resistant plants be dangerous to humans?
Are transgenic fish producing extra growth hormone dangerous to eat?
SCIENTIFIC OBJECTIONS TO GMOS
Safety issues from eating GMOs Could GM crops cause allergic
reactions? USDA now monitors GM foods for allergic
potential Toxicology study of GM plants (2003)
concluded that ingestion of current transgenic crops pose no significant health dangers
SCIENTIFIC OBJECTIONS TO GMOS
Environmental hazards posed by GMOs
Pollen from modified plants can carry GM genes to the wild plant population Could herbicide resistance genes be
transferred to weed species, creating superweeds?
Would they displace other plants in the wild, because they would be less likely to be eaten by insects?
SCIENTIFIC OBJECTIONS TO GMOS
Environmental hazards posed by GMOs
Could GM fish reduce biodiversity in the wild population if they escape? Reduced diversity in wild fish makes them
more susceptible to catastrophic disease outbreaks
THE HUMAN GENOME
Should parents be given information about the genetic health of an unborn fetus?
THE HUMAN GENOME
Should parents be allowed to select the genomes of their offspring?
Embryos from in vitro fertilization are currently tested before implantation
Many unused embryos are discarded
THE HUMAN GENOME
Should parents be allowed to design or correct the genomes of their offspring?