* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download molecular genetics
Survey
Document related concepts
Deoxyribozyme wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Molecular cloning wikipedia , lookup
Point mutation wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Therapeutic gene modulation wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
DNA vaccination wikipedia , lookup
Primary transcript wikipedia , lookup
Cre-Lox recombination wikipedia , lookup
Polycomb Group Proteins and Cancer wikipedia , lookup
History of genetic engineering wikipedia , lookup
Transcript
UNIT 3! Answer questions 1,2,and 3 on the bottom of page 204. Before the 20th Century: It was believed that proteins were the hereditary material (because they are so prevalent in the cell) Friedrich Miescher 1869 Used pus cells to investigate the material inside the nucleus Called this substance nuclein. did not behave like proteins. Did not know this was the hereditary material. Hammerling 1930s Used Acetabularia, a one-celled green algae to investigate WHERE hereditary information was stored in the cell. Reaches 5 cm in length: great to work with. Three distinct parts: Foot (contains the nucleus) Stalk cap The hereditary information must be in the foot (and possibly the nucleus) He furthered his experiments: Two species of Acetabularia: Grafted stalk of A.c onto foot of A.m. A. Mediterranea: disk-shaped cap A. Crenulata: branched, flowerlike cap. Subsequent cap was an intermediate between the two species: because substances that determined cap type were still in the stalk. Excised the cap and found that the new cap formed was A. m: substances in the transplant were used up under the control of the new nucleus. Concluded that YES, the hereditary material is in the nucleus. Nucleus was known to be the site of hereditary information. Chromosomes consist of both DNA and proteins. Which one was responsible for inheritance? Not until 1952 that DNA accepted as hereditary material. Conducted experiments using a virus, bacteriophage T2: __________________. (Bacteriophages are commonly called phages) Two components DNA Protein coat. How viruses work: Attach to membrane Inject hereditary information (PROTEIN COATS REMAIN OUTSIDE OF THE CELL) DNA of phage takes over cell mechanics Cell makes components (proteins and nucleic acids) of the virus Cell assembles components into new viruses New viruses burst out of the cell, resulting in host cell’s death New viruses can then infect other cells. Key aspects: Proteins contain sulfur but no phosphorous DNA contains phosphorus and no sulfur Hershey and Chase tracked the location of DNA and proteins throughout infection. Tagged some viral proteins with an isotope of sulfur, 35S Tagged some viral DNA with an isotope of phosphorus, 32P. Both 35S and 32P are radioisotopes: emit radiation as they decay: can be tracked. Both types of tagged T2s were allowed to infect bacterial cells. Cells put in blender and centrifuged to isolate bacteria parts (pellet) and viral parts (liquid) Results? Bacterial cells infected by 35S – containing viruses did NOT contain any radioactivity. Bacterial cells infected by 32P – containing viruses DID contain radioactivity. THEREFORE, PHOSPHORUS-RICH DNA WAS INJECTED INTO THE BACTERIAL CELL. This must be the genetic information. Page 209, #2, 3, 4, 5.