Biotechnology

Essential Content

A. Predicting Impact on Society, Individual, and Environment (16.10)

1. Cloning

2. Genetic Engineering

3. Artificial Selection

4. Transgenics

B. Medical and Ethical Issues (16.10, C.1.4)

1. Genetically Modified Crops & Animals

2. Genetic Testing

3. Disease Prevention & Treatment

4. Personal Identification

Objectives

· Evaluate examples of biotechnology (cloning, genetic engineering, artificial selection, GMO) on the individual, society and/or the environment.

· Evaluate impacts of biotechnology on the on the individual, society and/or the environment. (ALD)

· Describe how basic DNA technology is used to construct recombinant DNA molecules (i.e. gene therapy)

· Describe some of the issues (medical and ethical) that relate to biotechnology.

Bioethics, cloning, genetic engineering, artificial selection , genetically modified (GM), biotechnology, PCR, gene therapy, plasmid, CRISPR, stem cell, recombinant DNA

Selective Breeding Through selective breeding, humans choose organisms with wanted characteristics to produce the next generation.

This takes advantage of natural variation among organisms and passes wanted traits to offspring.

The numerous breeds of dogs and varieties of crop plants and domestic animals are examples of selective breeding.

Hybridization crosses dissimilar individuals to bring together the best of both parents in the offspring. Inbreeding is the continued breeding of individuals with selected characteristics. It ensures that wanted traits are preserved, but can also result in defects being passed on.

Increasing Variation Mutations are the source of biological diversity. Breeders introduce mutations into populations to increase genetic variation. Biotechnology is the application of a technological process, invention, or method to living organisms. Selective breeding is one example of biotechnology.

Radiation and chemicals can increase the mutation rate. Diverse bacterial strains have been bred from mutated lines.

Drugs can prevent the separation of chromosomes during mitosis, leading to polyploidy in plants. Such plants may be larger or stronger than their diploid relatives.

Copying DNA Genetic engineers can transfer a gene from one organism to another to achieve a goal, but first, individual genes must be identified and separated from DNA. The original method (used by Douglas Prasher) involved several steps:

Determine the amino acid sequence in a protein.

Predict the mRNA code for that sequence.

Use a complementary base sequence to attract the predicted mRNA.

Find the DNA fragment that binds to the mRNA.

Once scientists find a gene, they can use a technique called the polymerase chain reaction to make many copies.

Heat separates the DNA into two strands.

As the DNA cools, primers are added to opposite ends of the strands.

DNA polymerase adds nucleotides between the primers, producing two complementary strands. The process can be repeated as many times as needed.

Changing DNA Recombinant DNA molecules contain DNA from two different sources. Recombinant-DNA technology can change the genetic composition of living organisms.

Plasmids are circular DNA molecules found in bacteria and yeasts; they are widely used by scientists studying recombinant DNA, because DNA joined to a plasmid can be replicated.

A genetic marker is a gene that is used to differentiate a cell that carries a recombinant plasmid from those that do not.

Transgenic Organisms Transgenic organisms contain genes from other species. They result from the insertion of recombinant DNA into the genome of the host organism. A clone is a member of a population of genetically identical cells.

Agriculture and Industry Genetic engineers work to improve the products we get from plants and animals.

Genetically modified crops may be more nutritious or higher yielding. They may be resistant to insects, diseases, or spoilage. Some can produce plastics.

Genetically modified animals may produce more milk, have leaner meat, or contain higher levels of nutritious compounds. Transgenic salmon grow rapidly in captivity. Transgenic goats produce spider silk in their milk.

Health and Medicine Recombinant DNA studies are leading to advances in the prevention and treatment of disease.

Examples include vitamin-rich rice, human proteins made in animals, animal models of human disease (for research), and bacteria that produce human insulin.

Gene therapy is the process of changing a gene to treat a disorder. However, gene therapy is still an experimental and high-risk technique.

Genetic testing can identify hundreds of inherited disorders.

Not all genes are active in every cell. DNA microarray technology lets scientists study thousands of genes at once to determine their activity level.

Personal Identification DNA fingerprinting analyzes sections of DNA that may have little or no function but that vary from one individual to another.

DNA fingerprinting is used in forensics—the scientific study of crime-scene evidence— to identify criminals. It is also used to identify the biological father when paternity is in question.

Common ancestry can sometimes be determined using mitochondrial DNA (mtDNA) and Y-chromosome analysis.

Manipulating DNA Since the 1970s, techniques have been developed that allow scientists to cut, separate, and replicate DNA base-by-base. Using these tools, scientists can read the base sequences in DNA from any cell.

Restriction enzymes cut DNA into smaller pieces, called restriction fragments, which are several hundred bases in length. Each restriction enzyme cuts DNA at a different sequence of bases.

The Human Genome Project was a 13-year international effort to sequence all 3 billion base pairs in human DNA and identify all human genes. The project was completed in 2003.

The researchers identified markers in widely separated strands of DNA.

They used “shotgun sequencing,” which uses a computer to match DNA base sequences.

To identify genes, they found promoters, exons, and other sites on the DNA molecule.

To locate and identify as many haplotypes (collections of linked single-base differences) in the human population as possible, the International HapMap Project began in 2002.

The Human Genome Project identified genes associated with many diseases and disorders. From the project came the new science of bioinformatics, the creation and use of databases and other computing tools to manage data. Bioinformatics launched genomics, the study of whole genomes.

The human genome project pinpointed genes and associated particular sequences in those genes with numerous diseases and disorders. It also found that the DNA of all humans matches base-for-base at most sites, but can vary at 3 million sites.

The 1000 Genomes Project, launched in 2008, will catalogue the variation among 1000 people.

Profits and Privacy

Most of the research in genetic engineering is done by private companies.

They patent their findings and inventions to protect their investment and make a profit.

The patents block other scientists from pursuing certain lines of research.

In 2007, the Genetic Information Nondiscrimination Act was signed into law in the United States. It prohibits discrimination based on genetic information.

Safety of Transgenics

There is controversy about the safety of GM (genetically modified) foods.

Proponents of genetically modified foods argue that GM crops are better, safer, and higher yielding than conventional crops. GM crops require less land and energy to grow, and insecticides need not be applied to insect-resistant strains. Careful studies have provided no support for concerns about the safety of GM crops.

Opponents argue that the safety of GM crops has been neither adequately tested for long-term use, nor regulated. Patents on GM seeds may force small farmers out of business. The resistance of GM plants to insects may harm beneficial insect species. Resistance to herbicides may result in the overuse of toxic chemicals.

Some states have introduced legislation to require that GM foods be labeled.

Ethics of the New Biology

Few argue that gene therapy for curing disease is ethically wrong, but many ask the question of how far genetic modification should go.

Is it right to try to engineer children to have certain characteristics?

Should human cloning be allowed?