Presentation on theme: "Unit-IV GENE SEQUENCING Gene Sequencing and the Human Genome Project."— Presentation transcript:
Unit-IV GENE SEQUENCING Gene Sequencing and the Human Genome Project
Gene Sequencing DNA sequencing uses electrophoresis to separate DNA fragments of different lengths. A DNA synthesis reaction is set up that includes DNA from the region being investigated. The reaction also includes: DNA Polymerase A specific DNA primer All DNA nucleotides A small amount of 4 kinds of chemically altered DNA nucleotides.
As a group, the DNA molecules that are created by this technique have the following properties: They all start at the same point, because they all started with the same primer. There are copies of DNA molecules that had their replication halted at each nucleotide in the sequence of the sample DNA when a dideoxyribose nucleotide was incorporated. DNA molecules of the same length are labeled with the same color of fluorescent dye.
Gene Sequencing and the Human Genome Project The Human Genome Project (HGP) is an international scientific research project with a primary goal of determining the sequence of chemical base pairs which make up DNA, and of identifying and mapping the approximately 20,000–25,000 genes of the human genome from both a physical and functional standpoint. HGP was a 13 year effort to determine the human DNA sequence. Work began in 1990. It was first proposed in 1986 by U.S department of Energy (DOE). Many countries like-Australia, Brazil, Canada, China, Denmark, France, Germany, Mexico, Sweden etc. contributed both funds and labour resources to the Human Genome Project. While the objective of the Human Genome Project is to understand the genetic makeup of the human species, the project has also focused on several other nonhuman organisms such as E. coli, the fruit fly, and the laboratory mouse. HGP was one of the most ambitious projects ever undertaken in the biological sciences.
Human Genome Project Goals The specific goals of the HGP are to:: Identify all the estimated 80,000 genes in the human DNA, Determine the sequences of the 3 billion DNA chemical bases. Store this information in databases, Develop tools for data analysis, and Address the possible ethical, legal, and social issues.
Advantages of Human Genome Project: Knowledge of the effects of variation of DNA among individuals can revolutionize the ways to diagnose, treat and even prevent a number of diseases that affects the human beings. It provides clues to the understanding of human biology.
Human Genome Project Technique Two steps are followed- First, physical maps were constructed by determining the location of specific “markers” and the proximity of these markers to genes. The markers were known sequences of DNA that could be located on the last chromosome. This physical map was used to organize the vast amount of data produced by the second technique, which was for the labs to determine the exact order of nitrogenous bases of the DNA for each chromosome.
Human Genome Project Applications Human Genome Project Applications The information provided by the human genome project is extremely useful in diagnosing diseases. Providing genetic counselling to those considering having children. This info can identify human genes and proteins that can targets for drugs and new gene therapies.
GENE CLONING Cloning a gene means isolating an exact copy of a single gene from the entire genome of an organism. Usually this involves copying the DNA sequence of that gene into a smaller, more accessible piece of DNA, such as a plasmid. This makes it easier to study the function of the individual gene in the laboratory. Cloning gene means cutting the source DNA into smaller, manageable pieces with restriction enzymes.
Plasmid A plasmid is one example of a vector that is used to carry DNA into bacterial cells. It is a circular piece of DNA that is found free in the cytoplasm of some bacteria. The Plasmid can be cut with a restriction enzyme, so that the plasmid DNA will have sticky ends, which can attach to the source DNA. The enzyme ligase creates the bond between the plasmid DNA and the source DNA. The plasmid and its inserted source DNA is recombinant DNA.
Genetically Modified Organisms The GMO organisms are genetically engineered to contain genes at least from one other species. They contain recombinant DNA Viruses, bacteria, fungi, plants, and animals are the examples of organisms that have been engineered so that they contain genes from atleast one unrelated genes. GMO’s are capable of expressing the protein- coding regions found on recombinant DNA.
Applications of GM technology The primary application is to put herbicide- resistance or pest-resistance genes into crop plants. Edible GM crops are used for animal feed. Insertion of genes from a specific kind of bacterium called Bacillus Thuringiensis israeliensis (Bti) produces a protein that cause destruction to the insects and pest. GMO’s are used with a great success to clean up oil spills and toxic waste dumps, the process known as BIOREMEDIATION.
Recombinant DNA procedures are also responsible for- Human Insulin, used in the control of diabetes. Nutritionally enrched “golden rice”, capable of supplying poor people in less developed countries with beta- carotene which is missing from normal rice. Interferon, used as an antiviral agent. Human growth hormone, used to stimulate growth in children lacking this hormone.
Genetically Modified Foods Crops such as corn, soyabean, sugar beet, rice, cotton are short list of GM crops being grown and sold. Such crop have the potential of supplying the essential amino acids, fatty acids and other nutrients. Turnip can produce interferon, an antiviarl agent. Tobacco can create antibodies to fight human diseases. Oil seed plants can serve as a source of human brain hormones. As the population is growing, GM food may be an important part of meeting the need for food.
Basic Review What is the purpose of PCR? What benefits does human genome project offer? What role does Electrophoresis play in DNA comparisons? Describe how viruses are used in gene therapy. What are the advantages of creating GM foods? What are some of the concerns?
GENE THERAPY The field of biotechnology allows scientists and medical doctors to work together and potentially cure genetic disorders. Unlike contagious diseases, genetic diseases cannot be transmitted, because they are caused by a genetic means for a particular disorder- not separate, disease causing organisms such as bacteria and viruses. Gene therapy involves inserting genes, deleting genes and manipulating the action of genes in order to cure or lessen the effects of genetic diseases.
STEM CELLS Stem cells are cells that are self-renewing and have not yet completed determination or differentiation, so that they have the potential to develop into many different cell types. Scientists can generate stem cells by nuclear transfer techniques; they also occur naturally through out the body. They are involved in many activities including tissue regeneration, wound healing and cancer treatment.
Embryonic and Adult Stem Cells Embryonic stem cells have not undergone determination and differentiation and have the ability to become any tissue in the body, they are of great interest to scientists. As an embryo develops, its stem cells go through the process of determination and differentiation to create all the necessary tissues. To study the embryonic stem cells, scientists must remove the embryos, destroying the embryos.
Adult Stem Cells Adult stem cells are “tissue-specific”. These are found in the red bone marrow, where they divide. Example is hematopoietic stem cells as these cells are able to become many different types of cells found in blood-red blood cells, white blood cells and platelets. The disadvantage of using these types of stem cells is that they have already become partially determined and do not have potential to become every cell type.
Concept Review What benefits does stem cell research offer? What are some of the concerns with research on stem cells? Embryonic stem cells are found in embryos and adult stem cells are found in adults. In what other way they are different?