1. List proteins (enzymes and other factors) involved in the process of DNA replication in E. coli. Explain the role of each of these proteins in replication. Dnaa recognizes oric, binds to 4 9 bp boxes and opens strand at 3 13 bp boxes, initiates replication Dnab helicase, moves along strand and seperates them DNac loads dnab onto the stand Ssb bind to single stands to keep them from rejoining Dna pol I removes nucleotide errors and replaces gaps Primase synthesizes rna primers for initiation of replication on both strand DNA pol III synthesizes new dna strand Ligase joins okazagi fragments together RNase h involved in removal of primer Topoisomerases regulate supercoiling 2. What is meant by replication being bidirectional? Semiconservative? Continuous and discontinuous? Bidirectional means it moves in both directions from origin of replication, on both strands, one strand being continonus from origin in one way, discontinuous in the other direction. Semiconservative, each replicated strand has one new strand and one parent strand Continous meaning that once dna pol III stards building off of RNA primer, it will continue until strand is completed, there are no gaps or breaks Discontinuous, several rna primers made on other strand, followed by dna strands, rna removed and gaps are filled 3. Contrast the role of DNA polymerase I and III in E. coli DNA replication. DNA polymerase is involved in removal of rna primers and filling with dNTPs, DNA polymerase III catalyzes the synthesis of the DNA strand from an RNA template. 4. Which subunit of DNA polymerase III provides processivity? Which protein complex loads this subunit onto the DNA? The beta clamp provides processicity. Processivity means that the polymerase will continue replicating and going along strand until it ends or it is unloaded. The alpha gamma subunit loads it onto dna. 5. How can discontinuos synthesis of the lagging strand keep up with continuous synthesis of the leading strand?