Chapter 11

Gene Technology

Section 1: Genetic Engineering

Section 2: Human Applications of Genetic Engineering

Section 3: Genetic Engineering in Agriculture

Section 1

Genetic EngineeringObjectives:•Describe four basic steps commonly used in genetic engineering experiments.•Evaluate how restriction enzymes and the antibiotic tetracycline are used in genetic engineering.•Relate the role of electrophoresis and probes in identifying a specific gene.

Section 1

Genetic EngineeringBasic Steps of Genetic Engineering•Genetic Engineering Genetic engineers manipulate DNA for practical purposes.•Restriction Enzymes Restriction enzymes cleave DNA into fragments that have short sticky ends.• Steps in a Genetic Engineering Experiment (1) Cut DNA, (2) Recombinant DNA is produced, (3) The gene is cloned, and (4) Cells are selected and screened for gene of interest.

Section 1

Genetic EngineeringBasic Steps of Genetic Engineering continued

•Cutting DNA and Making Recombinant DNA Restriction enzymes are used to generate sticky ends. Sticky ends allow DNA fragments from different organisms to join together to form recombinant DNA. •Cloning, Selecting, and Screening Cells Recombinant DNA is inserted into host cells. Each time the cells reproduce, the gene of interest is cloned. The cells are then screened to identify cells that have the recombinant DNA.

Section 1

Genetic EngineeringConfirmation of a Cloned Gene•Gel Electrophoresis Electrophoresis uses an electric field within a gel to separate DNA fragments by their size. •Identifying a Gene of Interest Specific genes can be identified with DNA or RNA probes using the Southern blot technique.

Section 2

Human Applications of Genetic Engineering

Objectives:•Summarize two major goals of the Human Genome Project.•Describe how drugs produced by genetic engineering are being used.•Summarize the steps involved in making a genetically engineered vaccine.•Describe how gene therapy is being used to try to cure genetic disorders.•Identify two different uses for DNA fingerprints.

Section 2

Human Applications of Genetic Engineering

The Human Genome Project•Human Genome Project The Human Genome Project is an effort to determine the nucleotide sequence of and map the location of every gene on each human chromosome. The sequence of the genomes of many organisms has already been determined. •The Geography of the Genome Large amounts of DNA do not encode for proteins. •The Number of Human Genes Human cells contain only about 30,000 to 40,000 genes.

Section 2

Human Applications of Genetic Engineering

Genetically Engineered Drugs and Vaccines

•Drugs Genetic engineering is used to manufacture human proteins for use as drugs.•Vaccines Genetic engineering is used to manufacture human proteins for making safer and more effective vaccines.

Section 2

Human Applications of Genetic Engineering

DNA Fingerprinting•DNA Fingerprinting DNA fingerprinting is used to identify individuals and determine relationships between individuals.

Section 3

Genetic Engineering in Agriculture

Objectives:•Describe three ways in which genetic engineering has been used to improve plants.•Summarize two ways in which genetic engineering techniques have been used to modify farm animals.•Summarize the cloning of sheep through the use of differentiated cells.

Section 3

Genetic Engineering in Agriculture

Improving Crops•Better Crops Crop plants can be genetically engineered to have favorable characteristics, including improved yields and resistance to herbicides and destructive pests. •More Nutritious Crops Genetic engineers have been able to improve the nutritional value of crop plants, such as rice enriched with iron and vitamin A.

Section 3

Genetic Engineering in Agriculture

Risks of Genetically Modified Crops•Potential Problems There may be unforeseen negative effects of using genetically modified crops such as producing herbicide resistant crops and allergy problems.•Are GM Crops Harmful to the Environment? The possibility of GM crop genes being introduced to other organisms poses a potential risk.

Section 3

Genetic Engineering in Agriculture

Gene Technology in Animal Farming•Improving or Modifying Farm Animals Genetically engineered growth hormone increases milk production in dairy cows and weight gain in cattle and hogs.•Making Medically Useful Proteins Transgenic animals have foreign DNA introduced to their cells. For example, introducing medicinal human genes to farm animals can lead to the production of vital human proteins in animals’ milk.

Section 3

Genetic Engineering in Agriculture

Gene Technology in Animal Farming continued

•Cloning From Adult Animals The cloning of farm animals using differentiated cells was accomplished in 1997. In addition, transgenic animals can be cloned and used to make proteins that are useful in medicine.

Section 3

Genetic Engineering in Agriculture

Problems With Cloning

•Developmental Problems Problems in cloning lie within a developmental process that conditions eggs and sperm so that the right combination of genes are turned “on” or “off” during development.•The Importance of Genomic Imprinting In genomic imprinting, chemical changes made to DNA prevent a gene’s expression without altering its sequence. This allows for control over gene expression in clones.

Section 3

Genetic Engineering in Agriculture

Problems With Cloning continued

•Why Cloning Fails Problems in development related to genomic imprinting can lead to technical problems in cloning.