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They conduct experiments on rats using viruses to observe the outcomes, and they notice that viruses can change from harmless to harmful for reasons that remain unknown. -
Nucleic acids (DNA and RNA) carry the instructions for life. DNA stores info, and RNA helps make proteins. They are made of small building blocks called nucleotides. -
DNA is made up of a sugar (deoxyribose), a phosphate group, and four nitrogenous bases (adenine, thymine, cytosine, and guanine). These components were discovered in the early 20th century, and in 1953, Watson and Crick described the double helix structure that stores genetic information. -
They confirm that viruses change due to DNA through experiments with proteins and DNA. From then on, they realize that DNA, not protein, is the carrier of information. -
Around 1950, Chargaff found out that in DNA the amount of A is always the same as T, and C is always the same as G. This showed that the bases go in pairs, which is really important for how DNA works. -
Linus Pauling said that DNA was shaped like a triple helix, with three strands coiled together, but this model did not fit with experiments and did not properly explain how DNA worked. -
Hershey and Chase proved that DNA, not protein, is the genetic material by doing experiments with viruses and bacteria. They used radioactive labels to see which part of the virus went into the cell. -
Rosalind Franklin took very sharp X-ray pictures of DNA that were used to discover. That it had a double helix shape. Her work was key to Watson and Crick arriving at their idea. -
Watson and Crick discovered that DNA has a double helix shape and that the two strands are joined by base pairs. This helped to understand how DNA is copied and genetic information is passed on. -
Watson and Crick said that DNA is shaped like a double helix, with the nitrogenous bases on the inside and the sugar-phosphate chains on the outside. This way of being ordered makes DNA stable and can be copied.