Introductory Genetics

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<p>Introductory Genetics</p> <p>RIFAT ALI KHESHGI Student at NWFP AGRICULTURAL UNIVERSITY PESHAWAR Cell # 03139556067</p> <p>GeneticsIs the science of heredity. Heredity is the transmission of genetic or physical traits from parent to offspring.</p> <p>Gregor MendelAustrian Monk Considered the Father of Heredity He conducted plant breeding experiments in their monastery garden. In 1865 he made his work public, units of inheritance.</p> <p>What makes us unique?Each of the 100 Trillion cells in our body except the red blood cells contains the entire human genome, in the nucleus of every cell is the genetic information blueprint to construct the individual. It is the Deoxyribonucleic acid (DNA) Function of DNA </p> <p>Genetic code for almost every organism. Provide template for protein synthesis.</p> <p>Composition of DNAThe structure of DNA was discovered by Watson and Crick in 1953. It is a twisted double helix molecule, containing sugar, phosphates, and nitrogenous bases. The sugar is deoxyribose and the phosphoric acid molecules are always the same and provides for the structure (side of the ladder). The only difference between us is the order and arrangement of the four bases (rungs of the ladder).</p> <p>Bases of DNAAdenine= A Thymine= T Guanine= G Cytosine= C A always pairs with T C always pairs with G</p> <p>Bases of RNAAdenine= A Uracil= U Guanine= G Cytosine= C G always pairs with C T from the DNA = A in the RNA A from the DNA = U in the RNA</p> <p>DNA Model</p> <p>ChromosomesThe DNA in every cell is located in rod like segments called chromosomes Chromosomes occurs in pairs in every cell of our body except in the sperm and ovum. Chromosomes numbers are the same for each specie.</p> <p>Chromosome NumbersSpecie Cattle Swine Sheep Horse Human Chicken Goat Donkey Diploid # 60 38 54 64 46 78 60 62 Haploid # 30 19 27 32 23 39 30 31</p> <p>ChromosomesThere are 2 sex chromosomes included in the diploid number of the chromosomes. All of the other chromosomes are referred to as autosomes. In mammals if the sex chromosomes are alike, XX it results in a female. If the sex chromosomes are different, XY it results in a male.</p> <p>Sex DeterminationFemale can contribute only a X chromosome towards the sex of their offspring. Male can contribute an X or a Y chromosome toward the sex of their offspring. Absence of an Y chromosome results in a the embryo developing into a female. Presence of an Y chromosome results in the embryo developing into a male.</p> <p>Sex DeterminationGametogenesis = Formation of gametes through meiosis. Male = 4 viable spermatids Female = 1 viable ovum, 3 polar bodies.</p> <p>Tell me what I am ?????</p> <p>Tell me what I am ?????</p> <p>Cell DivisionMeiosis</p> <p>Is the form of cell division which results reducing the chromosome number from the diploid # to the haploid #. Occurs only in the sex cells, sperm and ovum. Is the form of cell division which results in the formation of identical daughter cells, keeps the chromosome number constant. Tissue growth and repair. Occurs throughout the body except in the sex cells.</p> <p>Mitosis</p> <p>Genotype or GameteGenotype contains two copies of the gene.</p> <p>AaBB</p> <p>Gamete (sex cells) contains only one copy of the gene.</p> <p>AB</p> <p>Determine the possible gametes of AaBB</p> <p>AB</p> <p>aB</p> <p>Gamete or GenotypeState if its a gamete or genotype. Aa D DdEeFFgg sRtxyq AaBBeeFF adgEFT</p> <p>List all the possible gametes.From the genotype AaBb AB Ab aB ab</p> <p>GenesChromosomes contains several units of inheritance genes. Genes usually occurs in pairs, one from each parent. Some traits are inherited directly from one set of genes. Some traits are inherited through several sets of genes.</p> <p>GenesIt was presumed that we were composed of about 100,000 genes to construct us. Today, research has proven that number is a lot less than 100,000. Extra credit for the student that can find an article about the current number of genes.</p> <p>Terms to knowHomozygous- contains 2 identical genes for the same trait, AA, BB, cc Heterozygous- contains 2 different genes for the same trait, Aa, bB, Cc Phenotype- Outward appearance of a trait, coat color, polled, horned. Genotype- Genetic classification of a gene, AA, Aa, aa. Allele- Location of a gene on the chromosome. F-one = First cross mating. F-two = Second cross mating.</p> <p>What are dominant genes?The gene that express itself, the powerful and dominant gene. It has the power to overshadow the recessive gene when there is complete dominance. Some examples are: </p> <p>White faced in cattle Droopy ears in swine Polled in cattle Black coat color in Angus cattle</p> <p>What are Recessive Genes?The gene that is overshadowed by a dominant gene Recessive genes can only express themselves in the absence of the dominant gene Polled vs Horned (Pp) (pp) Black wool vs white (Ww) (ww) Dwarfism vs normal size (dd) Albino</p> <p>Punnet SquareAngus- Black coat color is dominant. BB = Homozygous Dominant and Black Bb = Heterozygous and is black bb = Homozygous recessive and red A heterozygous bull is mated to 50 homozygous recessive cows. How many calves are black? How many calves are red? What is the genotypic and phenotypic ratios?</p> <p>Punnet Square</p> <p>B b b Bb Bb</p> <p>b bb bb</p> <p>Results2 heterozygous = Bb 2 Homozygous Recessive bb 25 Black, 25 Red Genotypic ratio = 0:2:2 Phenotypic ratio = 2 Black: 2 Red</p> <p>What are Sex Linked Genes?Some recessive genes are attached to the X and Y chromosomes Humans: Colorblindness and Baldness are on the X chromosomes In Men, traits expressed anytime present In Women, must have two recessives to show trait Children get baldness from mothers</p> <p>If Dad is bald, will you be bald?</p> <p>XB</p> <p>Y</p> <p>X</p> <p>XXB XXB</p> <p>XY</p> <p>X</p> <p>XY</p> <p>Baldness is carried by the mother</p> <p>X</p> <p>Y</p> <p>XB X</p> <p>XX B XX</p> <p>XY B XY</p> <p>What if Mom is bald?</p> <p>X XB XB XX B XX B</p> <p>Y XY B XY B</p> <p>What is Incomplete Dominance?If both genes express themselves Shorthorn Cattle: Red male mated to a White female = Roan calf RR crossed rr = Rr</p> <p>Punnet SquareShorthorn Cattle RR = Red rr = white Rr = roan If a red bull (RR) is mated to a white cow (rr), what color will the calves be?</p> <p>Shorthorn: Red X White</p> <p>R r Rr r Rr</p> <p>R Rr Rr</p> <p>Punnet SquareIf a red bull (RR) is mated to a roan (Rr) cow, what color will the calves be?</p> <p>Shorthorn: Red X Roan</p> <p>R R RR r Rr</p> <p>R RR Rr</p> <p>What if Both Parents are Roan?</p> <p>R R RR r Rr</p> <p>r Rr rr</p> <p>What is a Mutation?Dramatically different from what is expected genetically Horned calf from polled parents Loss of some or extra body parts Lethal Mutation: causes death at birth Sublethal Mutation: limits animals ability to grow to maturity Beneficial Mutation: loss of tail in lambs</p> <p>What is Heritability?Chance that traits will be inherited Low: multiple births, fat covering Medium: birth wt, wean wt, milk, wool grade, carcass wt, rate of gain High: Loin eye area, fleece length &amp; quality</p> <p>Mating SystemsUpgrading: mating purebreds with grade animals Inbreeding: mating closely related animals Linebreeding: mating distantly related animals Outcrossing: mating unrelated animals in the same breed. Crossbreeding: mating animals of same species but different breeds.</p> <p>What is Hybrid Vigor? HeterosisOffspring will outperform either of the parents Corn Breed A yields 100 bu/acre Corn Breed B yields 100 bu/acre Crossbreed A &amp; B yields corn that yields 200 bu/acre Vigor only expressed in crossbreeding</p> <p>The EndYou can use your notes to do the next two worksheets. Thanks</p>