1. 7.1: NUCLEIC ACIDS

2. 1. HERSHEY-CHASE EXPERIMENTS Alfred Hershey and Martha Chase researched the genetic material of viruses. They used the T2 bacteriophage (simple structure). They knew that: DNA contains phosphorous but not sulphur Protein contains sulphur but not phosphorous

3. 2. ROSALIND FRANKLIN’S X-RAY DIFFRACTION 1950: Franklin made improvements to the equipment (camera) and procedure for isolating DNA. Until she was able to calculate the dimensions of the double helix.

4. VIEWING NUCLEOSOMES -What do you remember about nucleosomes? -What is the function of a nucleosome? Go to: http://www.rcsb.org/pdb/home/home. do http://www.rcsb.org/pdb/home/home. do Follow the instructions on page 348, purple box.

5. ENZYMES OF REPLICATION EnzymeFunction HelicaseSeparates the strands (breaks H- bonds) TopoisomeraseReleased before helicase, ahead of the replication fork Single stranded binding proteins Separate the strands RNA primerInitiates activity of DNA polymerase DNA primaseCreates RNA primer DNA polymeraseAttaches new nucleotides DNA ligaseConnects fragments of replicated DNA

6. NON CODING REGIONS OF DNA The majority of the genome for eukaryotes is non-coding. There are many repetitive sequences – in humans almost 60% of the total genome is repetitive. Telomeres contain a large amount of repetitive code (they ‘protect’ the genes near the end of the chromosome)

7. PROMOTER The promoter is an example of a non-coding region of DNA that has a function. The promoter is the binding site for RNA polymerase, the promoter is not transcribed but proteins would not be produced without it.