Smooth colonies of bacteria killed mice.

1. DNA makes RNA in a process called transcription. RNA makes proteins in a process called translation. When the heat-killed deadly colonies were mixed with the rough colonies… the mouse died! Smooth colonies of bacteria killed mice. Rough colonies of bacteria did not kill mice. When the deadly smooth were treated with heat, they did not kill mice. Samples showed LIVING smooth colonies.

2. Avery, McCarty, and McLeod re-created Griffith’s experiment, but decided to find out exactly what compound was responsible for the transformation. They added enzymes that killed specific molecules (lipids, carbohydrates, RNA, DNA, proteins) to samples of the heat-killed deadly smooth bacteria. Then they mixed the heat-killed smooth and the living rough bacteria. It was found that transformation failed to occur only the sample where DNA was destroyed – meaning, DNA was the transforming factor!

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4. Phages that were radioactively labeled were allowed to infect bacteria. After infection, the mixture was agitated to separate the bacteriophages from the bacteria. The mixture was centrifuged, and a pellet of bacteria at the bottom showed that only the radioactively labeled DNA – NOT the radioactively labeled protein – had been injected into the bacteria. This means that DNA – NOT proteins – must be the genetic material.

5. A pairs with T; G pairs with C. One pyrimidine always pairs with one purine. A & G are purines, T & C are pyrimidines.

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7. The double helix structure of DNA. Watson & Crick 5-carbon sugar and phosphate group The phosphate group gives it a slightly negative charge. Sugar Phosphate T Nitrogenous base A C G

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