3Independent Assortment Mendel wanted to know:Does the segregation of one pair of alleles affect that of another?For example: Does the allele for seed color effect the shape of the seed?1. To find this Mendel created a two factor cross and followed two different genes as they passed from one generation to the next.
4The Two Factor Cross: F1Crossed true breeding plants for round (RR) yellow (YY)peas2. Genotype (RRYY)With true breeding plants for wrinkled (rr) green (yy) peas2. Genotype (rryy)And proceeded to observe the offspring
6The F1 Results: 3. This shows that the dominant alleles are present: Phenotype:HeterozygousRound Yellow SeedsGenotype:RrYy4. Does this result show if genes segregate independently?Nope
7The Two Factor Cross: F25. Mendel took the F1 generation (heterozygous) and crossed them.He wanted to see if the two traits would separate independently of one another or if dominant would stick with dominant and recessive stay with recessive.Was very curious of the possible outcomes.
9The F2 Results: 6. & 8. There was a total of 556 seeds produced: Round Yellow: 315Round Green: 105Wrinkled Yellow: 104Wrinkled Green: 327. There were seeds that displayed combinations not found in the parents (RRYY and rryy)Did Independent assortment occur?YES!
10Let’s Look at the Numbers Again: 9. Count up the Phenotypes, what is the ratio?9:3:3:1Round Yellow: 9RRYY, RrYyRound Green: 3RRyy, RryyWrinkled Yellow: 3rrYY, rrYyWrinkled Green: 1rryy
1111. Independent Assortment The alleles for a given trait segregate independently of one another and do not influence each other’s inheritance.
1212. A Summary of Mendel’s Principles The inheritance of biological characteristics is determined by genes that are passed down from parents to their offspring13. Two or more forms of a trait may exist (ex: Dominant and Recessive)The copies of genes are segregated from each other when gametes are formedThe alleles for different genes usually segregate independently from one another
13Beyond Dominant and Recessive 14. There are some alleles that are neither dominant or recessive, and many traits:Genetics tends to be a bit more complicated than that:The majority of genes have more than two alleles, and important traits are controlled by many different genes.
1415. Incomplete DominanceCases in which one allele is not dominant over the otherThe heterozygous phenotype is somewhere between the two homozygous phenotypesEx:Strawberry Blonde4 ‘o Clock Plants
1515. Codominance Both alleles contribute to the phenotype Ex: Both alleles will be shown in the offspringEx:Erminette AnimalsBlack feathers iscodominant with whiteOffspring show both colorsHumansProteins synthesis
1615. Multipe Alleles Genes that have more than two possible alleles This does not mean that an individual can have more than two alleles for a geneIt means that there could be more than two possibilities in a populationEx:Rabbit fur colorBlood Types in humans
1815. Polygenic Traits Traits that are controlled by two or more genes Many traits are produced by the interaction of several genesEx:Human Skin Color4 genes control skin colorHuman Eye Color
19Applying Mendel’s Principles Thomas Morgan- Geneticist that worked with Fruit Flies to test Mendel’s Principles of Segregation16. Chose Fruit Flies because:Small in sizeEasy to take care of in a lab settingCapable of producing large numbers of offspring very quickly17. The conclusion:Mendel’s Principles apply to not just pea plants, but other organisms as well
20Genetics and the Environment 18. Genes are not the only factor for determining characteristics of an organismThe Environment plays a role as wellEx: Sunflower Height is determined by the genes, but this will change depending on factors such as climate, water availability, and soil composition
21X Exit Slip bbCc Bbcc Katy Perry Wolverine Hair Color: -B: Black -b: BlueClaws:-C: No Claws-c: ClawsbbCcBbcc