1. DNA! Part 1

2. The Scientists ScientistsResearch QsConclusions GriffithWhat causes virulence in bacteria? The ability to cause disease is heritable. (Side note: polysaccharides are not responsible for causing disease) AveryWhat organic compound is the transforming factor that allows harmless bacteria to produce harmful offspring? DNA (by ruling out proteins and lipids) Hershey & Chase What is the molecule of heredity? DNA (has the instructions to build new viruses) **Packet page 7**

3. Catalyst (You can do this catalyst in space that you find on page 8 of your packet) You are studying a segment of DNA that is 200 base pairs long. 15% of the total monomers in this molecule are guanine. How many nucleotides are there in total? _____ What percent of the nucleotides are thymine? _____ How many thymine nucleotides are there? _____ How do you know this?

4. Nucleic acids DNA (deoxyribose nucleic acid) and RNA (ribonucleic acid) are both nucleic acids The monomers of nucleic acids are nucleotides All nucleotides have a nitrogenous base, a sugar, and a phosphate group There are 4 DNA nucleotides, they are named after their nitrogenous bases: Guanine **Packet page 8**

5. DNA structure Double helix (two connected twists) with uniform diameter. The shape was discovered by Watson and Crick when they viewed an x-ray produced image made by Rosalind Franklin (without her permission).

6. DNA structure Watson and Francis Crick worked out how the helix formed using pieces of information from other scientists –Franklin: the sides of the "ladder" are made of connecting sugars and phosphate groups, the nitrogenous bases are on the inside –Erwin Chargaff: the amount of adenine is always equal to the amount of thymine; and, the amount of guanine is always equal to the amount of cytosine ("Chargaff's Rules")

7. DNA structure: base pairing Since purines are larger than pyrimidines, the only way for a uniform thickness of DNA was to have a purine always pair with a pyrimidine: adenine pairs with thymine, guanine pairs with cytosine