Presentation on theme: "Basic Terms and Concepts. Knowledge of DNA has led to an ability to manipulate the genes of organisms We can clone genes and then use them to alter the."— Presentation transcript:
Basic Terms and Concepts
Knowledge of DNA has led to an ability to manipulate the genes of organisms We can clone genes and then use them to alter the genome of viruses and cells Known as genetic engineering
Cloning the production of identical copies of an organism through asexual means Gene cloning the production of identical copies of a single gene Accomplished through Recombinant DNA technology Polymerase chain reaction (PCR)
Reasons for gene cloning Produce large quantities of a gene’s protein product Ex: insulin Learn how a cloned gene codes for a particular protein Use the genes to alter the phenotypes of other organisms in a beneficial way When used to modify humans it’s referred to as gene therapy Organisms with foreign DNA or genes inserted into them are called transgenic organisms
Recombinant DNA (rDNA) Contains DNA from two or more different sources Ex: human cell and bacterial cell To make rDNA, a researcher needs a vector Vector: a piece of DNA that can be manipulated such that foreign DNA can be added to it Example: plasmid a very small accessory ring of DNA from bacteria that are not part of the bacterial chromosome and are capable of self-replicating
Polymerase Chain Reaction Can create billions of copies of a segment of DNA in a test tube Amplifies a targeted DNA sequence Requires the use of DNA polymerase and nucleotides Involves 3 basic steps that occur repeatedly to create many copies of DNA copies exponentially
Analysis of PCR Each person has a unique collection of DNA fragment size Gel Electrophoresis An electrical current is used to force DNA through a porous gel material Fragments are separated according to their size Smaller fragments move farther through the gel than larger fragments Result in a pattern of distinctive bands called DNA Fingerprints
Types of cellular cloning
Besides recombinant DNA, there are two other types of cloning Reproductive & therapeutic cloning Reproductive cloning a technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal Ex: Dolly was a sheep created by reproductive cloning technology. Process Somatic cell nuclear transfer (SCNT Involves the transfer genetic material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material, has been removed The reconstructed egg containing the DNA from a donor cell must be treated with chemicals or electric current in order to stimulate cell division. Once the cloned embryo reaches a suitable stage, it is transferred to the uterus of a female host where it continues to develop until birth
Therapeutic Cloning Also called "embryo cloning,” The production of human embryos for use in research Goal of this process is not to create cloned human beings, but rather to harvest stem cells that can be used to study human development and to treat disease. Stem cells are important to biomedical researchers because they can be used to generate virtually any type of specialized cell in the human body. Stem cells are extracted from the egg after it has divided for 5 days. The egg at this stage of development is called a blastocyst
Medical applications for Therapeutic cloning Treatment for degenerative diseases Alzheimer's’ Stroke and heart diseas Nerve disorders like Parkinson's, Disorders involving paralysis or degeneration of the spine Muscular dystrophy Demylination ALS, ALD Designer cancer therapy Generation of “tailor made” organs No need for anti-rejection drugs Decreases demand for transplant organs
Application for Organ Transplants Known as organogenesis: the growth, or creation, of organs using stem cells To do this, DNA would be extracted from the person in need of a transplant and inserted into an enucleated egg. After the egg containing the patient's DNA starts to divide, embryonic stem cells that can be transformed into any type of tissue would be harvested The stem cells would be used to generate an organ or tissue that is a genetic match to the recipient In theory, the cloned organ could then be transplanted into the patient without the risk of tissue rejection. If organs could be generated from cloned human embryos, the need for organ donation could be significantly reduced
Bacteria, plants, and animals that are transgenic are more commonly called genetically modified organisms (GMO) Products from GMO’s are called biotechnology products Ex: blood clotting factors, insulin, human growth hormone, hepatitis B vaccine
Transgenic Bacteria Produced using recombinant DNA Grown in vats called bioreactors The bacteria express the cloned gene, and the gene product is usually collected from the medium where the bacteria is grown Uses Medical: insulin & vaccines Agriculture: use of bacteria to make frost- resistant plants, insect-resistant corn Bioremediation: naturally occurring bacteria that eat oil can be genetically engineered to do an even better job of cleaning up oil spills Biochemistry: a certain bacteria is used to create phenylalanine, an organic chemical used to make aspartame, an artificial sweetener
Transgenic plants Foreign genes are placed into protoplants, or immature plant embryos Will develop into mature plants that express the foreign DNA Example Pomato Plant produces potatoes below ground and tomatoes above ground Foreign genes transferred to cotton, corn,a dn potato strains have made them resistant to pests Cells produce insect toxin
Transgenic animals Method of DNA combination: Vortex mixing Eggs are placed in an agitator with DNA and slicon-carbide needles The needles make tiny holes in the eggs through with the DNA can enter When the eggs are fertilized, the resulting offfspring are transgenic animals Applications Eggs have acquired the gene for bovine growth hormone, which produces larger fish, cows, pigs, rabbits, and sheep Gene pharming The use of transgenic farm animals to produce pharmaceuticals Genes that code for therapeutic and diagnostic proteins are incorporated into an animal’s DNA, and they appear in the milk Examples Cystic fibrosis, cancer, and blood diseases
Gene Therapy & the Human Genome Project
Gene therapy is a treatment that involves altering the genes inside your body's cells to stop disease. Genes that don't work properly can cause disease. Gene therapy replaces a faulty gene or adds a new gene in an attempt to cure disease or improve your body's ability to fight disease. Gene therapy holds promise for treating a wide range of diseases, including cancer, cystic fibrosis, heart disease, diabetes, hemophilia and AIDS. Currently, in the United States, gene therapy is available only as part of a clinical trial.
Researchers are testing several approaches to gene therapy, including: Replacing a mutated gene that causes disease with a healthy copy of the gene. Inactivating, or “knocking out,” a mutated gene that is functioning improperly. Introducing a new gene into the body to help fight a disease.
One challenge is gene delivery how to get the new or replacement genes into the desired tissues Use of a vector is needed Most effective vector is the use of harmless viruses Virus DNA is removed and replaced with the new or replacement genes Gene is delivered via the vector to the host cells Stem cells containing the desired gene can also be used as a vector, which are incorporated into the affected tissue
Example Imagine, for example, a little boy with hemophilia, a condition that is caused by a faulty gene that makes his liver unable to make blood clotting factor 8 Gene therapy would involve putting a working copy of the gene which codes for factor 8 into his liver cells so that his liver could then produce adequate levels of factor 8
Human Genome Project an international research effort to sequence and map all of the genes of members of our species, Homo sapiens known as the genome Completed in April 2003 HGP gave us the ability, for the first time, to read nature's complete genetic blueprint for building a human being
Project Goals identify all the approximately 20,000-25,000 genes in human DNA determine the sequences of the 3 billion chemical base pairs that make up human DNA store this information in databases improve tools for data analysis transfer related technologies to the private sector address the ethical, legal, and social issues (ELSI) that may arise from the project.