11/1/2009 Biology: 11.2 Human Applications Genetic Engineering Human Applications Genetic Engineering

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering T he Human Genome Project:  The Human Genome Project is a research project linking 20 labs in six countries.  Teams of scientists in the project worked to identify and map all 3.2 billion base pairs of all the DNA that makes up the human genome.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering T he Human Genome Project:  One of the most surprising things about the human genome is the large amount of DNA that does NOT encode proteins.  In fact, only about 1 to 1.5% of the human genome is DNA that codes for proteins. Each human cell contains about 6 feet of DNA but less than 1 inch is devoted to exons.  (recall that exons are sequences of nucleotides that are transcribed and translated)

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering T he Human Genome Project:  Exons are scattered about the human genome in clumps that are not spread out evenly among the chromosomes.  On most human chromosomes, great stretches of untranscribed DNA fill the chromosomes between the scattered clusters of transcribed genes.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering T he Number of Human Genes:  When they examined the complete sequence of the human genome, scientists were surprised at how few genes their actually are.  Human cells contain about 30,000 to 40,000 genes. This is only about double the number of genes in a fruit fly.  It is only about one quarter of the 120,000 genes scientists had expected to find.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering T he Number of Human Genes:  How did scientists make such a large mistake estimating the number of genes? — When scientists had counted messenger RNA (mRNA) they had found over 120,000. Each of these can in turn be translated into a unique protein. — Scientists had “expected” to find as many types of genes as their were different types of mRNA molecules.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering G enetically Engineered Drugs and Vaccines:  Drugs: Many genetic disorders and human illnesses occur when the body fails to make critical proteins.  J uvenile diabetes is such an illness. — The body is unable to control levels of sugar within the blood because a critical protein, insulin, cannot be made. — These failures can be overcome if the body can be supplied with more of the protein it lacks.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering G enetically Engineered Drugs and Vaccines: — Today, pharmaceutical companies worldwide produce these medically important proteins using bacteria and genetic engineering in combination.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering G enetically Engineered Drugs and Vaccines:  Today many genetically engineered medicines are used to treat everything from burns to diabetes.  Examples include: — Erythropoetin for anemia — Growth factors for treating burns, ulcers — Human Growth Hormone for growth defects — Insulin for diabetes — Interferons for viral infections and cancer — Taxol for ovarian cancer

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering G enetically Engineered Drugs and Vaccines: V accines:  Many viral diseases, such as smallpox and polio, cannot be treated by existing drugs. Instead, they are combated by prevention through use of vaccines.  A vaccine is a solution containing all or part of a harmless version of a pathogen (disease-causing microorganism).  It is a weakened version of the disease; incapable of causing serious harm”

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering G enetically Engineered Drugs and Vaccines: V accines:  When a vaccine is injected, the immune system reads the pathogen’s surface proteins and responds by making defensive proteins called antibodies. The immune system creates a defense system against this form of the disease.  In the future, if the same pathogen enters the body, the antibodies are now there to combat the pathogen and stop it’s growth before it can cause a disease. The immune system stays in place so when the flu or cold strikes in full force, the antibodies are already there to fight it before it can grow.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering G enetically Engineered Drugs and Vaccines: V accines:  Traditionally, vaccines have been prepared by either killing a pathogenic microbe or by making the microbe unable to grow.  The disease causing microbe is rendered into a “weakened form” ; strong enough to cause a reaction in the immune system but not strong enough to make the taker ill.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering G enetically Engineered Drugs and Vaccines: V accines:  This ensures that the vaccine itself will not cause the disease but only activate the antibodies to form.  With these types of vaccines there is always some small danger for getting sick as some people are more sensitive to the vaccine. Their threshold is lower.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering G enetically Engineered Drugs and Vaccines: V accines:  Vaccines made by genetic engineering avoid this danger and are less likely to risk infection to those who are extra-sensitive to the microbes.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering D na Fingerprinting:  Other than identical twins, no two individuals have the same genetic material.  Scientists use DNA sequencing technology to determine a DNA fragment’s nucleotide sequence.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering D na Fingerprinting:  Because the places a restrictive enzyme can cut depend on the DNA sequence, the lengths of the DNA fragments will vary between any two individuals.  A DNA fingerprint is a pattern of dark bands on photographic film that is made when an individuals DNA restriction fragments are exposed to an X-ray film.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering D na Fingerprinting:  Because these bandings are unique to every individual, they are like fingerprints.  The banding patterns from any two individuals can be compared to determine if they are related.  Because fingerprinting can be performed on a sample of DNA from blood, bone, or hair; DNA fingerprinting is used in forensics as a tool.

11/1/2009 Biology: 11.2 Human Applications Genetic Engineering D na Fingerprinting:  DNA fingerprinting can also be used to identify the genes that cause genetic disorders, such as Huntington’s Disease and Sickle cell Anemia.

11/1/2009 Computer Lab:  Use the internet to go online and write a one paragraph mini-report on the following topic: DO NOT COPY CUT OR PASTE:  How is DNA fingerprinting used in the science of modern forensics to solve crimes?

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