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This text explains the discoveries of Griffith, Avery, Hershey-Chase, Watson, and Crick regarding the role of DNA in transmitting genetic information. It covers the concepts of transformation, nucleotides, DNA structure, and nitrogen base pairing.
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12-1 DNA and RNA
Griffith • Griffith was trying to figure out how bacteria made people sick • Isolated two strains of pneumonia bacteria for mice • They were easy to grow in a culture and easy do distinguish between the two types by look
Griffith mixed some of the deadly strain of the bacteria that had been killed with the harmless strain of bacteria. • Alone both were harmless but the mixture caused the mice to get pneumonia and die • Somehow the killed bacteria passed their disease causing ability to the harmless strain • Transformation – when an organism is permanently changed into another
Avery • Oswald Avery discovered that the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next
Hershey-Chase • Used bacteriophages to test Avery’s discovery and concluded he was correct • Bacteriophages – virus that infects bacteria
Components and Structure of DNA • DNA is a long molecule made up of units called nucleotides • Nucleotides – units that make DNA, made of 3 parts. • Sugar • Phosphate • Nitrogen base
The Double Helix • Watson and Crick two scientist that discovered the structure of DNA • DNA is made up of nucleotides that connect to each other and repeat over and over • This make a ladder shape that then twists
Nitrogen base pairing • 4 possible nitrogen bases • Adenine, Guanine, Cytosine, Thymine • A always bonds with T A-T • G always bonds with C G-C