Bell Work • A set of parents have 4 children. One is dominant, one is recessive, and two are heterozygous for a trait. • What is the genotype of the parents?
Bell Work • Who is “the father of genetics”? • Who came up with the double helix model? • Who did an experiment on fruit flies? • Who did an experiment on rats?
Write these three questions on your bell work: • What are the chemical components of DNA? • What clues helped scientist solve the structure of DNA? • What does the double-helix model tell us about DNA?
Objectives • Understand the historical discovery of DNA. • Know the chemical structures of DNA including the effectiveness of the double helix. • Understand hydrogen bonding in regards to base pairs.
History of DNA page 349. • Gregor Mendel-1865 • Father of Genetics • Showed that characteristics in pea plants can be passed in a predictable way. • In USA history: 13th amendment abolishing slavery was passed.
History of DNA page 349. • Walter Sutton- 1903 • First one to realize that chromosomes hold genetic material. • American geneticist
History of DNA page 349. • Thomas Hunt Morgan • Showed that genes are arranged linearly on the chromosomes of a fruit fly. • Gene Linkage: pg. 328. some traits are closer together on the chromosome, so they are more likely to be inherited together. • The closer two genes are to each other, the less likely they will be divided during crossing over.
History of DNA page 349. • Frederick Griffith- 1928 • Bacteria contain a molecule that can transfer genetic information from cell to cell. • Pg. 339 figure 12-1 • Transformation: one type of bacteria (harmless) is permanently changed into another bacteria (disease causing). • USA History- mickey mouse first appears. Herbert Hoover is President. 1929 the Great Depression happens.
History of DNA page 349. • 1944- Oswald Avery, Colin Macleod, Maclyn McCarty • Discover that the nucleic acid DNA stores and transmits genetic information from one generation to the next.
History of DNA page 349. • Hershey-Chase-1952 • Repeat the Avery experiment and confirm the results. pg. 341 figure 12-3 • History: Elizabeth II becomes queen (like the current queen of England).
History of DNA page 349. • Watson and Crick: 1953 • Publish their model of DNA double helix. • Rosalind Franklin: purified DNA, stretched it out and then X-ray beamed it. This gave her a diffraction photo of DNA. • Watson and Crick were working on their double helix model when they say Franklins picture.
History of DNA page 349. • They realized that their double helix model was correct and explained Chargaff’s rule • Chargaff’s Rule: there are an equal number of Adenines and Thymines and guanines and cytosines in each DNA strand. • Antiparallel- The DNA runs in opposite directions, ensuring that the nitrogenous bases are in the center of the cell.
History of DNA page 349. • Craig Venter and Francis Collins: 2000 • Draft of the human genome DNA sequence. • The final verison was published in 2003.