Exam IV Outline

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BIOL 133
Denise Woodward

Bio 133 Exam 4 Outline Chapter 19 Genetic Engineering and Genetically Modified Organisms (GMOs) • Biotechnology: use or alteration of cells or biomolecules for specific purposes – Transgenic Organisms: an organism with DNAfrom another species – Recombinant DNA: adding foreign genes to cells – Gene Targeting: moves a gene to a particular location • Mice don’t get polio. • Lack receptor for virus. • Transgenic mice express human gene for polio receptor – can be infected by polio virus – develop characteristics of disease Transgenic Sheep • produce human protein alpha1-antitrypsin – treat deficiency which causes damage to lungs/liver GMO primates • 2001 – 1 GMO monkey • useless “marker” genewas inserted • shows promise for human gene therapy GMO primates - 2009 • Transplanted gene is heritable • Researchers now plan to create families of monkeys that develop neurodegenerative diseases similar to those seen in humans • Genetic technologies are possible because the genetic code is universal • Polymerase Chain Reaction (PCR): amplifying (copying) pieces of DNAto create many copies • PCR Uses: forensics, medical tests, genetic testing DNAToolbox • Restriction enzymes - cut DNAat specific locations – function like scissors • Ex: EcoR1 recognizes and cuts GAATTC • Sequence is a palindrome DNAToolbox • Restriction enzymes • DNALigase – attaches 2 pieces of DNAtogether (glue) The DNAToolbox • Restriction enzymes • DNALigase • Vectors - carry DNAto new location – plasmids – bacteriophages – retroviruses DNAToolbox • Restriction enzymes • DNALigase • Vectors • Recipient cells - cells to receive DNA Recombinant DNAtechnology • Example: Human insulin • 1 product produced through recombinant DNAtechnology Transgenic Organisms • New traits introduced to organism • Requires moving DNAinto cell – Plants: gene guns, Ti plasmid, and viruses – Animals: chemicals that open membrane, liposomes, electricity, and injections Ethics of GMOs • Many protests – why? • What do you think? Release of Genetically Modified Organisms • Microcosm experiments and Field Tests • Bioremediation: use of an organism's engineered abilities to remove toxins from the environment Phytoremediation Problems with the release of GMOs • economic concerns • ecological concerns • evolutionary concerns Transgenic Corn in Mexico • corn originated in Mexico • GM corn has been banned in Mexico (that may change this year) • Corn with GE genes found in mountains in 2001 Chapter 20 Genetic Counseling and Gene Therapy The role of genetic counselors • Genetic counselors are health care professionals trained in genetics and psychology. – Educate public about genetic information. – Evaluate risk based on personal and family history. – Determine whether and which genetic tests are appropriate. – Counsel patients before and after genetic test results. – Act as a resource for referral or support group information. Genetic counseling issues • Privacy – Confidentiality within society – Confidentiality within family • Nondirective information • Insurance • Role within the health care profession Preconception Comprehensive Carrier Testing • Asingle test that detects recessive mutations for 448 diseases – Severe phenotype – Several mutations known – Penetrance is high • Ethical concerns? Nutrigenetics Testing • Direct to consumer DNAtest coupled with questionnaire about lifestyle, diet, etc. • Government Accountability Office study: Don’t waste your money! Pharmacogenetics • Using genetics to match patients to drugs and doses – Identify patients likely to suffer a negative reaction to a drug – Select the most effective drug/dose – Monitor response to drug treatment – Predict the course of the illness • Gene Therapy: replaces malfunctioning gene - alleviate symptoms • Controversial science (successes and failures) • Eugenics: effort to breed better humans – encouraging reproduction of people with "good" genes and discouraging those with "bad" genes • "Those who cannot remember the past are condemned to repeat it." » George Santayana Somatic vs. Germline Therapy • Somatic: alters somatic cells – not passed to next generation • Germline: alters germ cells - passed to next generation – Not done in humans Therapeutic vs. Enhancement • Therapeutic: attempt to cure a disease • Enhancement: attempt to chose a child’s traits (strength, height, intelligence, etc.) The Mechanics of Gene Therapy • Ex vivo: genetic alteration of cells removed from patient and implanted back into patient • In vivo: direct genetic manipulation of cells in body – more invasive then ex vivo Early Success: Severe Combined Immunodeficiency (SCID) • Disease in which immune system is nonfunctional (lack of T and/or B cells) – ADADeficiency – X-linked SCID • Only human disease to be cured by gene therapy First Gene Therapy Patient –ADADeficiency • Ashanthi DeSilva • Gene therapy in 1990 at age 4. • She is now 26 years old and doing well. X-linked SCIDS – Successes and Failures • 14 children treated with gene therapy • 3 developed leukemia (one died) – insertion of retroviral vector near proto-oncogene LMO2 promoter led to uncontrolled proliferation of mature T cells – 11 others are cured ASerious Setback: OTC Trial • Ornithine transcarbamylase deficiency – lack of enzyme that helps break up proteins – ammonia accumulates in blood – Jesse Gelsinger: volunteered for gene therapy at age 18 • Jesse died 4 days later due to a massive immune response Amore recent success • Gene therapy for Leber congenital amaurosis type 2 (LCA2). – An inherited form of blindness – Gene therapy trials on sheep dogs had successfully treated the disease • Corey Hass (age 8) received gene therapy in 2008 Gene Therapy for LCA2 • Adeno-associated virus (AAV) carried wild-type version of gene into Corey’s eye Gene Therapy for LCA2 • Adeno-associated virus (AAV) carried wild-type version of gene into Corey’s eye • Corey told reporters at a press conference that for the first time he can recognize faces, play baseball, read large print books, and ride his bike around his neighborhood alone Chapter 21 Reproductive Technologies • Infertility: inability to conceive after 1 yr w/out contraceptives – 1/6 couples: trouble conceiving in US – 90%: physical basis – 30%: male infertility – 60%: female infertility – 20%: both Male Infertility: Oligospermia (1/30 men) •Normal sperm count: 20 - 200 million/ml. •Count < 20 million/ml = oligospermia. •Can have a genetic cause (Y chromosome) •Reproductive technologies can cause infertility to be passed on to offspring Oligospermia Antisperm antibodies • Blood-testes barrier prevents antibodies from getting to sperm • If barrier is broken, immune response can result Too much heat • Ex: Varicose vein in scrotum causes too much heat near developing sperm and they cannot mature • Ex: Too tight underwear, laptop in lap, hot tubs, etc. Genetic causes • lack of gene on Y chromosome that controls spermatogenesis Genetic causes • mutation in gene for androgen receptor – androgen-regulated genes required for spermatogenesis and sexual differentiation – testicular feminization – infertility Decreased sperm motility • physical defects Female Infertility • Hormonal problems – Irregular menstruation, polycystic ovarian syndrome (increased androgen levels lead to cysts), early menopause Female Infertility • Pelvic Inflammatory Disease (PID): bacteria infect reproductive organs • leading cause of female infertility (100,000 women/yr) Female Infertility • Endometriosis: tissue builds up in uterus and outside of uterus causes scarring and inflammation Infertility Tests: Laparoscopy • Female Infertility • Ectopic pregnancies: fertilized ovum implants on tissue other than endometrial lining of uterus. • ~40-50 women die/year in U.S. Female Infertility • Infections: STDs and other infections can damage reproductive organs • Surgical problems: scar tissue does not allow implantation Assisted Reproductive Technologies • Replace source of male/female gamete, aid fertilization or pregnancy. • Surrogate pregnancy • In vitro fertilization • Sperm or egg donor • Worldwide – about 250,000 births a year Intrauterine Insemination (donated sperm) • Donated sperm placed in woman’s reproductive tract (success is ~5-15% per try). • 1790: 1 reported pregnancy from IUI • 1953: methods for freezing/storing sperm Sperm Banks • Cost: ~$125-$615 (cost difference due to education level and more complete medical history information) • Couples can choose sperm from catalogs that lists features of donors (including non-genetic traits) Surrogate motherhood • Woman carries pregnancy to term for woman who cannot conceive and/or carry pregnancy. In vitro fertilization (IVF) • Sperm fertilizes egg in culture dish. • Embryos transferred to uterus for implantation. • 1978 first IVF child • ~25% success rate • higher rate of birth defects than natural birth Intracytoplasmic sperm injection (ICSI) • IVF accompanied by injection of sperm into oocyte • used in cases of low sperm count, abnormal sperm shape, sperm motility problems. Gamete/Zygote Intrafallopian Transfer • Gamete/zygote placed in woman’s uterine tube • Done less often than IVF • Can’t be done if woman has excessive scarring Oocyte donation • Eggs stored frozen (in metaphase II until fertilization occurs) • Women can store own eggs have children later undergoing chemotherapy work with teratogens • Donated eggs can be used by women with infertility problems. • Embryo adoption • Cytoplasmic donation (older women have oocytes injected with cytoplasm from oocytes of younger women) • Recipients of donated oocytes, embryos, and cytoplasm can be up to 55 years of age Preimplantation genetic screening and diagnosis (PGD) Detection of genetic abnormalities. Preimplantation genetic diagnosis • 1 cell of 8-celled embryo removed. Remaining cells complete development. • 1992:1 child born following PGD to screen for CF allele. • Combined w/ IVF for women with multiple miscarriages. Extra Embryos • There are approximately half a million extra embryos derived from IVF being stored in US • Fates: store, donate for research, donate to another couple, discard • Embryonic Stem Cells • IVF produces extra embryos • Embryos made up of embryonic stem cells – pluripotent cells • Research indicates therapeutic uses: Parkinson’s, Alzheimer’s, diabetes, spinal cord injuries Embryonic Stem Cells • Parents can donate these cells to science • Fetal stem cell technologies are controversial – Destruction of embryos – Ethically questionable research Polar Body Biopsy • Polar bodies can be analyzed for genetic problems • Only healthy oocytes used for IVF – should increase success of IVF and decrease number of excess embryos Chapter 22 The Human Genome Project The Human Genome Project • Determine the order of nucleotides in each chromosome. • Draft was announced in February 2001. • Final draft was completed in April, 2003 (50 anniversary of discovery of structure of DNA) • 2004: Number of genes in human genome reduced to 20,000 - 25,000 (from estimated 35,000) • 2008: Genetics Information Nondiscrimination Act, Human Genome Structural Variation Project • Future: Epigenetics Projects (such as NIH’s Roadmap Epigenomics Project) Discovery of the Structure of DNA • 1953 - Francis Crick and James Watson: Nature • 1962 - Nobel Prize in Physiology and Medicine Discovery of the Structure of DNA • Structure of DNAexplains how DNAis replicated • Genetic information: sequences ofA,C,G,T Genome Sequencing
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