Genes and Heredity

1. Genes and Heredity

2. HEREDITY • Passing on of characteristics from parent to offspring GENETICS • The branch of biology that studies heredity TRAITS Characteristics that are inherited

3. GREGOR MENDEL • “Father of Genetics” • Austrian monk • The first person to succeed in predicting how traits are transferred from one generation to the next

4. Mendel Studied Pea Plants... *Pea plants reproduce sexually, meaning they have two distinct sex cells—male and female *Sex cells are called GAMETES *Both gametes are in the same flower *FERTILIZATION occurs when the male pollen grain fuses with the female ovule

5. Mendel transferred pollen... • From one plant to another with different traits • He made crosses of the different traits • Studied only one trait at a time

6. Generations • P1 Generation= original parents • F1 Generation= offspring of original parents • F2 Generation= second filial generation that results when crossing two F1 plants • **F stands for “filial” ---son or daughter

7. The Rule of Unit Factors • Mendel concluded that each organism has two factors for each of its traits • These “factors” are GENES and they are located on the CHROMSOMES • Different forms of genes are called ALLELES

8. Rule of Dominance • DOMINANT TRAIT- the visible, observable trait, of an organism that masks a recessive form of a trait • RECESSIVE TRAIT- Hidden trait of an organism, masked by a dominant trait

9. The Law of Segregation • Mendel concluded that the two alleles for each trait must separate when gametes are formed • A parent only passes one allele (at random) for each trait to each offspring

10. Genotype or Phenotype? • Two organisms can look alike but have different underlying gene combinations. • The way an organism looks and behaves make up its PHENOTYPE—PHYSICAL DESCRIPTION • The gene combination an organism contains is known as it GENOTYPE