taboo rap gen lec
Post on 14-Jun-2015
Embed Size (px)
- 1. Prepared By:Montalbo, Daniel Justin B.De Castro, Ralph Louis R.
2. Mendels Law of Segregation states that there are two allelesfor every gene determining a specific characteristic, and thesealleles are segregated into separate gametes duringreproduction. When the 2 different alleles occur together in one individual(heterozygote), the dominant allele will be the one that isexpressed in the phenotype of the individual. The Law of Addition is used to combine probabilities, whenthere are 2 or more ways to arrive at a given outcome. The Law of Multiplication is used to combine probabilities of 2or more different events that need to occur in combination. Mendels Law of Independent Assortment says that 2 ormore different genes, if found on separate chromosomes, aredetermined independently of each other. Many characteristics have been found to follow patterns ofinheritance that are modifications of Mendels rules. 3. pure forked line genebreeding polygenes allele hybrid contributor dominant homozygous y allele recessive heterozygous non- contributor character P (parental y allelegeneration) trait continuous F1 (first filial variation phenotypgeneration) discontinuoe F2 (second us variation genotypefilialgeneration) Punnett 4. CHARACTERS TRAITS Pre-Mendel beliefs ingenetics: blendingtheory Augustinian monk andscience teacher Why Pisum sativum? Pea plants available inmany varieties character (heritable feature) trait (character variant) Perfect flowers cross-pollination andself-pollination Short generation time Many offspring 5. MONOHYBRID CROSSinheritance of a single trait P Generation (true-breeding xparents)PurpleWhite flowers flowers F1 Generation(hybrids)All plants hadpurple flowers self-pollination F2 Generation 705 plants224 plants 6. Allele for purple flowers Alternative versionsof genes existHomologous(alleles)Locus for flower-color gene pair of Dominantchromosomes Recessive Organism inheritesAllele for white flowers2 alleles Dominant is fullyexpressed Recessive has novisible effect Law of segregation 2 alleles for onecharacterseparate and goto differentgametes 7. True-breeding plants have identical P Generationalleles.xPurple flowersWhite flowersGametes each contain only one allelePP ppfor the flower-color gene. Every gameteAppearance:produced by one parent has the same allele.Genetic makeup: Pp Gametes:F1 hybrids have a Pp combination.Purple-flower allele is dominant, F1 Generationall hybrids have purple flowers. Purple flowersHybrid plants produce gametes,Appearance:Genetic makeup:Pptwo alleles segregate: half thegametes receiving the P allele and1/2 P 1 /2 p Gametes:the other half the p allele.Punnett square: shows all possibleF1 spermcombinations of alleles in offspringP pfrom an F1 x F1 (Pp x Pp) cross.F2 GenerationPEach square represents an equally probable PP Ppproduct of fertilization. F1 eggsp PpppRandom combination of the gametesresults in the 3:1 ratio that Mendel 3:1observed in the F2 generation. 8. Homozygous identical alleles,true-breeding Heterozygous different alleles Phenotype physicalappearance Genotype genetic make-up 9. APPLICATIONAn organism displaying the dominant phenotype can either Xbe homozygous or heterozygous for the trait. A test-cross willhelp determine which. Dominant phenotype,Recessive phenotype,unknown genotype: known genotype: TECHNIQUEPP or Pp?pp The individual with the unknown genotype is crossed with a homozygous individual expressing the recessive trait (white flowers in this example). By observing theIf Pp, If PP, phenotypes of the offspring resulting from this then 12 offspring purple then all offspring cross, we can deduce the genotype of the purple-flowered purple:and 12 offspring white: parent.p p pp RESULTS P PPpPp PpPp P pPp Pppppp 10. Illustrates theinheritance of twocharacters Produces fourphenotypes in the F2generation Law of Addition -combines probabilitiesfor mutually exclusiveevents The Law ofMultiplication -combines probabilitiesof 2 or moreindependent eventsthat need to occurtogether 11. Forked Line MethodAaBbCc x AaBbCc 12. 1. Codominance two dominant alleles affect phenotype in separate ways both alleles manifest e.g. roan coloring in horses both red and white2. Incomplete dominance phenotype of offspring is between phenotypes of two parents e.g. red and white parents give rise to pink offspring3. Multiple alleles genes with more than two alleles that control the phenotype e.g. ABO blood type system has 3 alleles--A,B,i. A and B are codominant, i is recessive to both