• Proteins originally thought to be gene material because of their limitless variations in strucutre and function and ability to hold large amounts of information
• DNA, knonw to be composed of four different deoxyribonucleotides was thought to be simple and uninteresting instructure before Watson and Crick
• Hershey and chase preformed an experiment with the T2 virus to determine whether it was DNA or protein that was genetic material
• T2 is a virus that affects bacteria by latching on the outside of the cell and injecting genetic info inside for the production of more of the T2 virus; it alters the genes of the bacterial cellwhich hosts this parasitic virus until it dies; the capsule the virus arrives in stays attached on the outside of the cell; T2 is made up almost exclusively of DNA
• To highlight the protein portion and DNA portion of T2, they grew the virusus in either radioactive sulfur (for proteins) or radioactive phosphorus (for DNA); each set were then allowed to infect E. Coli cells- if genes were made of DNA, the radioactive phosphorus would be inside the cells, and if proteins, the radioactive sulfur inside the cell; to test this the researchers removed the empty capsids from the outide of the cells and spun the cell the whole thing in a centrifuge; they cell material would form a pellet and the capsids would stay in the solution. Whichever radioactive material found in the pellet would determine which material genes are made of; radioactive phosphorus was found in the pellet, indicating DNA as genetic material

DNA: Adenine-Thymine, Guanin-Cytosine

RNA: Adenine- Uracil

Existing strands of DNA act as a template ofr the production of new strands

• Conducted an experiment to determine in what way parent DNA is present after replication
• Tested the semi-conservative,conservative, and dispersive hypothesises
• Used E.coli bacteria, because bacteria copy their DNA  or genome before every cells division
• Grew E. Coli first generation in N15 because the extra neutron would add heaviness, distinguishing the original DNA from the replicated DNA (distinguished by N14) later
• The cells grown in N15 were transfered then into a solution with only N14 for the second generation and after they were grown they were they were grown again in another N14 enviroment for the thrid generation
• Found the second generation had two hyrid molecules, consisting of a new strand and old strand and the third generation produced two of the same hybrids and two molecule consisting of wholly of the old DNA, supporting the semi-conservative replication

• helped with the discovery of DNA replication
• Catalyzes DNA synthesis
• Only works in one direction-5 prime to 3 prime
• Polymerase I and III
• Usually endergonic, but polymerization is exergonic in cells because the monomers that act as substrates are dNTPS

• Starts at the origin of replication, a specific sequence of bases
• Eukaryotes have multiple sites along each chromosome where DNA synthesis begins

• y-shaped region where parent DNA helix is split into single strands which are copied

• Splits hydrogen bonds