VIEWS: 12 PAGES: 39 POSTED ON: 3/23/2012
Genetics 101 By: Wong Wei Cong (32) Journey into DNA The genome is here before us; its chromosomes make me and you. We see them here in their most condensed state, each one will in no time be two. Forty-six of them make up the genome, half are mum’s and half are pop’s. They’ll soon split into two when the cell divides; there will be ninety-two when it stops. Journey into dna We zoom in to take a close look at… a single chromosome? Didn’t we say there are two here? Half of this “X” is a clone. Chromosomes when stained show banding, or areas of light and dark. What causes this trait is its structure, and the denseness of its parts. Journey into dna Here we behold a single gene, the unit of inheritance. If you’re short of thin or slim or bald, depends on its transmittance. Its length can vary greatly, its intricacy can’t be outdone. It can be as short as a hundred bases, Two million is a long one. Journey into dna A DNA molecule is very long, when stretched out end to end. To fit inside a small cell it’s developed this knack to bend. The DNA twists ‘round and ‘round like countless Hula Hoops. It creates a cord-like structure, which we called chromatin loops. The chromatin scaffold is vital, providing much-needed support. From it extend many more loops that a ruler would measure as short. Journey into dna We almost see the DNA strand as we look at some nucleosomes. It’s wrapped tightly on those round things, Which are structures called protein histones. The histones, they carry a plus charge; without it the strand’s in distress. For then the DNA would try to float free, And become a colossal mess. “It has a helical structure,” Watson and Crick forthrightly insisted. With two sides and the rungs that connect them, the DNA strand looks like a ladder that’s twisted. Journey into dna Here is a small piece of the ladder, untwisted to better your view. Please note that the bases displayed here, are paired up in groupings of two. Note also that there are four letters; and that’s all that they’ll ever be. They comprise the four DNA bases, and they are A, T, C and G. Development of life -Darwin's theory of evolution Natural selection Adaptation Diversity Over-reproduction On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life Development of life -Darwin's theory of evolution Natural selection Development of antibiotic resistance in microorganisms Produces adaptations Biodiversity arises by surviving evolution Development of life -Darwin's theory of evolution All living organisms have a single common ancestor Each species through time fit somewhere in an evolutionary Tree of Life. Darwin’s Tree of Life Modern Tree of Life Development of life -What Darwin didn’t know: Heredity Gregor Johann Mendel “Father of modern genetics” Australian monk & scientist Studied the inheritance of certain traits in pea plants Discovered the Laws of Inheritance Development of life -What Darwin didn’t know: Heredity Parent plants Development of life -What Darwin didn’t know: Heredity 2nd Generation Development of life -What Darwin didn’t know: Heredity 3:1 3rd Generation Development of life -What Darwin didn’t know: Heredity Parent plants 2nd Generation 3rd Generation Development of life -What Darwin didn’t know: Heredity DOMINANT RECESSIVE Development of life -What Darwin didn’t know: Heredity Development of life -What Darwin didn’t know: Heredity Parent plants 2nd Generation 3rd Generation Development of life -What Darwin didn’t know: Heredity Development of life -What Darwin didn’t know: Heredity Punnett Square Development of life -We have found the secret of Life By 1953 Watson and Crick was on the case, they were the dynamic duo that deciphered DNA. Must be in double helix like a spiral staircase, with Gs married to Cs and Ts paired to As. We see here the famous arrangement discovered by Watson and Crick. Based on the work of Ms. Franklin, Their model was at once declared slick. Other genetic concepts Multiple alleles Incomplete dominance Other genetic concepts Co-dominance Mutation? Weird Genetics-What is mutation? A change in genetic information Failure of DNA repair Mutate a sentence! – The fat cat ate the wee rat. – The fat hat ate the wee rat. (Point mutations) – The fat caa tet hew eer at. (Frame shift mutations) – The fat ate the wee rat. (Deletion) – The fat cat xlw ate the wee rat. (Insertion) – The fat tar eew eht eta tac. (Inversion) Weird Genetics-classification Hereditary mutations Acquired mutations Beneficial mutations (Murray Grey) Harmful mutations (Down Syndrome) Weird Genetics-classification Natural mutations Human intervention – Selective Breeding – Genetic Engineering Weird Genetics-selective breeding Breeding plants and animals for particular genetic traits (desirable characteristics) Inbreeding depression Reduced genetic diversity The Liger is the result of breeding a female Tiger to a male Lion. Weird Genetics-genetic engineering Ian made a little lamb, little lamb, little lamb. Ian made a little lamb and Dolly was her name. When she grew, she was just like Mom. Just like Mom, just like Mom. Why was she just like Mom? Their DNA’s the same! Weird Genetics- so what is GE? Selective change of genetic material by man Technique of removing, modifying or adding genes to a DNA molecule Scientists successfully ANDi (DNA inserted spelled genetically engineered a rat to backwards): The first grow a human ear on its back. genetically modified monkey Weird Genetics- gm food for thought Advantages: – Pest resistance – Herbicide tolerance – Disease resistance – Cold tolerance – Drought tolerance Bright face of genetically modified corn plant: pest-infected non-GM (left) and – Salinity tolerance pest-free GM plant (right) planted side-by- side in a field trial. (photo: Dr. Yu Jialin, – Nutrition China Agricultural University) – Medicine Weird Genetics- gm food for thought Disadvantages: • Environmental hazards o Unintended harm to other organisms o Reduced effectiveness of pesticides • Human health risks o Unknown effects on human health • Economic concerns o Corporate monopoly o Dependence on GM companies o Monoculture Weird Genetics- design-a-baby? Biotechnology critic Jeremy Rifkin: "It's the ultimate shopping experience: designing your baby.” Using genetic technologies to modify embryos and choose desirable characteristics Spare part children? Weird Genetics- the genetic menu MENU TODAY’S SPECIAL • TENNIS CHAMPION $19,000 (LIMITED OFFER!) APPETISERS • EYE COLOUR BROWN $10,000 BLUE $10,500 BLACK $9,500 • HAIR COLOUR BLACK $9,000 WHITE $10,000 RED $10,500 GREEN $12,000 (MUST TRY!) Weird Genetics- the genetic menu MENU SIDE ORDERS • SKIN TONE $9,50O • WEIGHT/HEIGHT $11,000 ENTREES • BEAUTY $20,000 • INTELLIGENCE $23,000 • GENDER $19,500 MAIN COURSE • MUSIC PRODIGY $25,000 Weird Genetics- the genetic menu MENU MAIN COURSE • GREAT ARTIST $25,000 • NOBEL PRIZE-WINNING SCIENTIST $26,000 • GENIUS PHILOSOPHER $26,000 • NEXT PRESIDENT OF AMERICA $40,000 DESSERT • WORLD-CLASS SPORTSMAN $25,000 • CANCER-FREE BABY $35.000 FOR FULL BABY MAKEOVER $1,500,000 TERMS AND CONDITIONS APPLY Weird Genetics- terms and conditions? Safety issues – Genes introduced at random places in genome – Many genes have more than one effect – Many traits we want to select are influenced by multiple genes Environmental influence? Discrimination? Imbalance between rich and poor? Loss of humanity? Is it right to experiment on babies? Other moral complications? genetic blueprint- Human Genome Project • 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 that may arise from project bibliography • http://www.youtube.com/ • http://www.wikipedia.org/ • http://www.bionetonline.org/ • http://www.dnai.org/ • http://www.science-class.net/ • http://www.pbs.org/ • http://www.amnh.org/ology/?channel=genetics • http://www.fossilmuseum.net/ • http://library.thinkquest.org/ • http://www.buzzle.com/ • http://learn.genetics.utah.edu/ • http://ghr.nlm.nih.gov/ • http://www.genetichealth.com/ • http://www.biology-online.org/ • http://science.howstuffworks.com/ • http://www.actionbioscience.org/ • http://nature.ca/genome/03/a/03a_10_e.cfm Thank y u!
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