2 How do we look the way we do? Proteins control our traitsWhat is a trait?a specific characteristic, for example, eye color or height that varies from one individual to another.The differences among these traits are called variations?the differences that an organism can inherit for a trait
3 Who discovered all this? Gregor MendelFather of GeneticsFirst person to describe how traits are passed on from each generation.Austrian monk in the early1800’sDiscovered the principles of geneticsStudied 7 characteristics of pea plants
4 Why peas? Mendel studied peas for several reasons They have distinct male and female partsThere are 7 basic characteristics of pea plantsThey can self-pollinate and cross-pollinate.
5 Terms to Know:Crosscombining gametes from parents with different traitsSelf-Pollinatepollination that occurs from the joining of pollen and ovary of the same flowerCross-Pollinationpollination that occurs from the joining of pollen and ovary of different flowersAlleledifferent forms of the same gene, the genes you inherit from your parents.Genelocated on chromosomes, they control how an organism developsFertilizationthe uniting of male and female gametes
6 Green pea pods x green pea pods Mendel’s experimentCross pollinatedGreen pea pods x green pea pods= All green podsSelf pollinatedGreen pods x green pods= ¾ green pods¼ yellow podsMendel took two pea plants and crossed them.What did he find?He discovered different laws and rules that explain factors affecting heredity.
7 Mendel’s Laws/Rules Law of Dominance Law of Segregation The trait that is observed in the offspring is the dominant trait (Use uppercase letters to describe)The trait that disappears in the offspring is the recessive trait (use lowercase letters to describe)The two alleles for a trait must separate when gametes are formedA parent randomly passes only one allele for each trait to each offspring
8 More Terms to Know Dominant The trait that is observed or expressed Use a capital letter (T)RecessiveThe trait that is covered up or not expressedUse a lowercase letter (t)HeterozygousIf the alleles for the inherited trait are different; one dominant and one recessiveUse a capital & lowercase letter (Tt)HomozygousIf the alleles for the inherited trait are the same; both dominant or both recessiveUse two capital letters or two lowercase letters (TT, tt)GenotypeThe gene combination of an organismTT, Tt, ttPhenotypeThe way that an organism looksTall/short