Chapter 1-2: Genetics Progressed from Mendel to DNA in Less Than a Century

1. Chapter 1-2:Genetics Progressed from Mendel to DNA in Less Than a Century By PresenterMedia.com

2. A Breakdown Item 1 Item 2 Chromosome Theory of Inheritance Genetic Variation Mendel’s Work Search for the Chemical Nature of Genes Item 3 Item 4

3. Mendel’s Work • Essential Point #1: Mendel’s work on pea plants established the principles of gene transmission from parent to offspring that serve as the foundation for the science of genetics.

4. Chromosome Theory of Inheritance • Essential Point #2: The Chromosome Theory of Inheritance explains how genetic information is transmitted from generation to generation.

5. Chromosome Theory of Inheritance • Terms to know: • Diploid (2n): 2 copies; found in body cells. • Homologous chromosomes: chromosomes appear in pairs. They are identical in size and location of centromeres. • Mitosis/Meiosis: Replication and division of chromosomes for cell distribution. • Haploid (n): half the copies; found in gametes. • Allele: alternative forms of a gene • Phenotype: observable features. • Genotype: the set of alleles for a given trait in the genetic code.

6. Genetic Variation • Results from any heritable change. • Discovery of mutations in eye color in Drosophila, fruit fly, the most common model organism in genetics. • These mutations can be found in the genes of gametes and are passed through sexual reproduction.

7. Genetic Variation • Heritable changes are called MUTATIONS. • MUTATIONS can: • Cause no change • Cause beneficial changes/ Natural Selection • Cause harmful changes

8. The Search for DNA or Protein? • Many researchers thoughtproteins were the chemical responsible for the passage of genes from parent to offspring. • 1944: Avery, etal proved that DNA was responsible for carrying genetic information in bacteria.

9. Questions to Consider • Can we apply Mendel’s theories to the inheritance of all traits? Give examples. • Why was it difficult for scientists to accept Avery, etal claim that DNA was the mechanism of heredity in 1944? (hint: when did Watson, Crick, and Franklin publish their findings?)

10. 1.3: Discovery of the Double Helix and Molecular Genetics • Once Avery, etal proved that DNA was the mechanism of inheritance, the stage was set in the discovery of its structure. • 1953: Watson & Crick described the molecular structure of DNA. • Awarded the Nobel Prize in 1962

12. Gene Expression: from DNA to phenotype Also known as the Central Dogma

13. Proteins and Biological Function • Proteins are the product of genetic expression. • What is/are the functions of proteins in living organisms? • 20 different Amino Acids = the building blocks of proteins. • Lets do the math… • Protein that contains 100 amino acids can have any one of the 20 A.A.’s at each location • 20 100 = 5 trillion possibilities!!! • 3-dimensional conformation of the protein is essential to its biological function. • Enzymes = shape is ESSENTIAL for bonding with chemicals at the active site.

14. Case StudySickle Cell Trait

15. Phenotype and Genotype: Sickle cell trait RESULT: Can’t bind to oxygen for transport.