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?