2. Genetics: The Science of Heredity A guide to Chapter 5

3. History of Genetics »Genetics: The study of heredity, or the passing on of traits from an organism to its offspring. »Trait: Characteristic

4. Gregor Mendel 1860’s1860’s Austrian monk and biologist who experimented with pea plants.Austrian monk and biologist who experimented with pea plants. The “Father of Genetics”.The “Father of Genetics”.

5. Dominant & Recessive Genes: Units of heredity. Each organism carries two genes for each characteristic.Genes: Units of heredity. Each organism carries two genes for each characteristic. Dominant: the trait that is the stronger of the two. (D)Dominant: the trait that is the stronger of the two. (D) Recessive: The weaker of the two traits that is masked by the dominant trait. (d)Recessive: The weaker of the two traits that is masked by the dominant trait. (d)

6. Symbols of Genetics: Geneticist: a scientist who studies heredity.Geneticist: a scientist who studies heredity. P1 Generation: Parental or 1 st generation.P1 Generation: Parental or 1 st generation. F1 Generation: Filial or 2 nd generation.F1 Generation: Filial or 2 nd generation. F2 Generation: 3 rd generation.F2 Generation: 3 rd generation.

7. Principals of Genetics Traits are passed from one generation to the next.Traits are passed from one generation to the next. Traits are controlled by genes.Traits are controlled by genes. Organisms inherit one gene from each parent.Organisms inherit one gene from each parent. Some genes are dominant and some recessive.Some genes are dominant and some recessive.

8. Continued: Dominant genes hide recessive genes. (Dd)Dominant genes hide recessive genes. (Dd) Some genes are neither dominant or recessive. They have Incomplete Dominance (RW).Some genes are neither dominant or recessive. They have Incomplete Dominance (RW). Purebred: (PP or pp) same genesPurebred: (PP or pp) same genes Hybrid: (Pp) different genes.Hybrid: (Pp) different genes.

9. Probability: The possibility, or likelihood, that a particular event will take place. It is used to predict the results of genetic crosses.The possibility, or likelihood, that a particular event will take place. It is used to predict the results of genetic crosses.

10. Punnett Square A special chart is used to show the possible gene combinations in a cross between two organisms.A special chart is used to show the possible gene combinations in a cross between two organisms. Developed by Reginald C. Punnett, an English geneticist.Developed by Reginald C. Punnett, an English geneticist.

11. A white rabbit Phenotypes: physical appearance or what an organism looks like (white).Phenotypes: physical appearance or what an organism looks like (white). Genotypes: The gene make-up of the organism. BB or Bb or bb.Genotypes: The gene make-up of the organism. BB or Bb or bb. A white rabbit: Phenotype? Genotype?A white rabbit: Phenotype? Genotype?

12. Chromosomes Walter Sutton: an American graduate student.Walter Sutton: an American graduate student. Developed the Chromosome Theory of Genetics.Developed the Chromosome Theory of Genetics. Genes are carried from parents to offspring on chromosomes.Genes are carried from parents to offspring on chromosomes. They are found in the nucleus and produce proteins.They are found in the nucleus and produce proteins.

13. Mitosis: Cell Division Mitosis: One cell divides into two identical cells. This happens in 4 phases or steps.Mitosis: One cell divides into two identical cells. This happens in 4 phases or steps.

14. Meiosis A process of cell division that produces sex cells: egg and sperm.A process of cell division that produces sex cells: egg and sperm. Each cell contains half the number of chromosomes as the original cell.Each cell contains half the number of chromosomes as the original cell.

15. DNA Deoxyribonucleic acidDeoxyribonucleic acid Stores and passes on genetic information from one generation to the next.Stores and passes on genetic information from one generation to the next. James Watson & Francis Crick (1962) discovered it.James Watson & Francis Crick (1962) discovered it. Chromosomes are made up of DNA. DNA contains the genes.Chromosomes are made up of DNA. DNA contains the genes.

16. Structure of DNA Atwisted ladder, the steps are the nitrogen bases. AdenineAdenine (A) GuanineGuanine (G) CytosineCytosine (C) ThymineThymine (T) Aonly pairs with T. Gonly pairs with C.

17. DNA Replication The process of DNA forming exact copies or duplicates.The process of DNA forming exact copies or duplicates. The DNA ladder unzips at the two nitrogen bases.The DNA ladder unzips at the two nitrogen bases. Free nitrogen bases match up with the pairs to make an exact copy.Free nitrogen bases match up with the pairs to make an exact copy.

18. Inherited Diseases Sometimes a structure of a gene contains an error.Sometimes a structure of a gene contains an error. Sickle Cell Anemia, Muscular Dystrophy.Sickle Cell Anemia, Muscular Dystrophy. Sex-linked traits carried only on the X chromosome.Sex-linked traits carried only on the X chromosome. Hemophilia & Colorblindness