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When live, harmless bacteria and heat-killed bacteria are mixed, the heat-killed bacteria passed on disease-causing information to the live cells of the harmless bacteria, causing harmless bacteria to “transform” into bad bacteria
This factor was probably a gene because he noticed that the offspring inherited the disease as well
Avery’s Experiments: DNA is the Transforming Factor
American biologist Oswald Avery, 1944
Was transforming factor DNA or Protein?
Took Griffith’s heat-killed bacteria and good bacteria and made an extract (aka a juice)
Treated this extract “protein-destroying enzymes”
Injected mice with the treated extract
Did the bacteria still function and kill the mice?
Yes, the bad bacteria still transformed the harmless bacteria…therefore protein did NOT contain the “transforming factor”
Treated Griffith’s deadly bacteria and harmless bacteria with “DNA-destroying enzymes”
Did they still function?
No, the bacteria was not transformed, therefore, DNA had to be the transforming factor
1952, American biologists Alfred Hershey and Martha Chase
Which is the hereditary material: Protein or DNA ???
Conducted Experiments using viruses
Package of nucleic acid wrapped in a protein coat
Not made of cells
Can only reproduce by infecting living cell with its genetic info
Genetic info of virus then tells the cell’s organelles to make more viruses
Bacteriophage (phage)-virus that infects bacteria…literally means “bacteria eater”
Virus attaches to the surface of bacteria, injects its genetic material into the bacteria, the viral genes cause many more viruses to be made inside the bacteria until the bacteria burst and hundreds of new viruses are released
Legend: Transcription of DNA to RNA to protein: This dogma forms the backbone of molecular biology and is represented by four major stages. 1. The DNA replicates its information in a process that involves many enzymes: replication. 2. The DNA codes for the production of messenger RNA (mRNA) during transcription. 3. In eukaryotic cells, the mRNA is processed (essentially by splicing) and migrates from the nucleus to the cytoplasm. 4. Messenger RNA carries coded information to ribosomes. The ribosomes "read" this information and use it for protein synthesis. This process is called translation . - Proteins do not code for the production of protein, RNA or DNA. -They are involved in almost all biological activities, structural or enzymatic.