Biotechnology: How Do We Use What We Know about Life?
Role of bacteria in technology • Advantage to using bacteria • Possess plasmids • Small extra loops of DNA • Experience transformation • Bacteria take up plasmids from surroundings
Role of bacteria in technology • Advantage to using bacteria: • Scientists can genetically engineer plasmids by inserting gene of interest into bacterial plasmid.
Gene Cloning • Definition: using bacteria to make multiple identical copies of a single stretch of DNA. • Useful in understanding eukaryotic genome. • Cloning Vector: • Any vehicle that inserts a fragment of foreign DNA into the genome of a host cell. • Example: virus or genetically engineered plasmid. • Used in gene therapy.
Genetic Engineering • Definition: Ability to precisely manipulate DNA sequences from widely different organisms. • Process requires • Ability to cut DNA • To insert foreign DNA segment • “Glue” DNA sequences together
Molecular Scissors • Restriction enzymes: • Cut DNA at specific places called recognition sites. • Form “sticky ends.”
Molecular Paste • DNA Ligase: • Form bonds between the sugar and phosphate backbone of the DNA molecule. • Restriction enzymes and DNA ligase make possible the combination of DNA from different organisms into one DNA molecule • Called recombinant DNA
How do we know what size DNA fragments we have? • Agarose gel electrophoresis: • Allows separation of DNA on the basis of size. • Can visualize DNA to determine exactly how large it is.
Making a DNA library • Need the following: • A gene of interest • Restriction enzymes • Plasmids • DNA ligase • Can create a cloning vector using these tools which can be inserted in a bacteria • Allow bacteria to reproduce • DNA library: entire collection of bacterial cells which contain cloned gene
Screening a DNA Library • Need to find the gene of interest in the bacteria or bacterial cells that possess the gene of interest. • Use nucleic acid hybridization to find the gene of interest.
Nucleic Acid Hybridization • Requires a molecular probe: • Probe is made of a synthetic single-stranded DNA whose sequence is complementary to the gene of interest. • Also has a built-in marker so scientists can find it. • When probe binds to denatured gene of interest, a hybrid is formed.
Polymerase Chain Reaction • Allows scientists to make copies of a small sample of DNA. • Requires: • Primers: two synthetic short strands of DNA that are complementary to each of the two DNA sequences that flank the gene or DNA to be copied. • Heat-resistant DNA polymerase • Nucleotides
DNA Sequencing • Determining the base-by-base order of the nucleotides in a stretch of DNA. • Can help us identify regions of DNA that contain genes.
DNA Sequencing • Makes possible comparisons of DNA sequences • between individuals to teach us about our susceptibility to disease. • between species to teach us about how we evolved. • Also, DNA sequences teach us about the regulation of gene expression.
Human Genome Project (HGP) • Overall goal: • decipher the full set of genetic instructions in human DNA. • Develop a set of instructions as a research tool for scientists.
Human Genome Project (HGP) • Several genomes of model organisms have been sequenced as a part of the project.
What We Have Learned From Human Genome • First lesson:Human DNA consists of 3 billion base pairs • Contain 20,000-25,000 genes • 2-3 times as many genes as a worm or fruit fly. • Approximately 3% of DNA contains the information to make proteins.
What We Have Learned From Human Genome • Second lesson: a greater understanding of genes themselves. • Has important implications to understanding human biology and what goes wrong in disease states. • Help us define disease states and predict possible candidates who are likely to suffer from a disease based on their nucleotide sequences.
What We Have Learned From Human Genome • Third lesson: lessons about the human family; both our diversity and evolution. • Compare base-by-base sequences of DNA • Any group of individuals have DNA sequences that are 99.9% identical regardless or origin or ethnicity. • Points in DNA sequence where the sequences are not identical between two or more individuals are called single nucleotide polymorphisms (SNPs)
HPG has Raised Ethical, Social and Legal Issues • Who owns genetic information? • Should people be tested for genetic disorders if there is no possibility of treatment?
How Do We Use Biotechnology? • Gene therapy: treatment of a genetic disease by alteration of the affected person’s genotype, or the genotype of the affected cells.
Stem Cells • Definition: undifferentiated cells in either an adult or embryo that can undergo unlimited number of cell divisions. • Are totipotent • Could be used to produce complex human tissues or replacement organs for people suffering from disease.
Designer Drugs • Biotechnology has made it possible to predict the precise shape of molecules. • Makes it possible to develop drugs for therapeutic use.
DNA in The Courtroom • Can be use to determine paternity • Identifying individuals in criminal and civil proceedings. • Use variable number tandem repeats (VNTR) as markers.
Biotechnology on The Farm • Goal: To increase the world’s food production while decreasing the costs and environmental damage due to insecticide and pesticide use.
Biotechnology on The Farm • Scientists have focused efforts on three areas: • Developing crops capable of fending off insect pests without the use of insecticides • Engineering plants with a greater yield that grow in a wider ranges of climates • Make crops that are resistant to herbicides , so that fields can be treated for weeds without damaging crops • Opponents wondering if we are disturbing ecological balance in the environment
Can Biotechnology Save The Environment? • Bioremediation: Use of microorganisms to decompose toxic pollutants into less harmful compounds.
Risks of Biotechnology • Two categories of risks: • Risks to human health • Risks to the environment
Questioning The Ethics of Biotechnology • Privacy and ownership of genetic information. • Argue altering genes is unnatural. • Breaches fundamental boundaries between species. • Are scientists interfering with the order of life?