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1. In E. Coli, two DNA polymerases synthesize the DNA in opposite directions. Th

ID: 192253 • Letter: 1

Question

1. In E. Coli, two DNA polymerases synthesize the DNA in opposite directions. The whole genome of E. Coli is 5 million base pair long. E. Coli replicates its whole DNA every 3000s (10 points) (a) What is an estimated rate for DNA replication of E. Coli (4 points)? (b) A typical mRNA transcript is 1000 bases long and DNA polymerases take 25 seconds to make typical mRNA transcript. What is an estimated rate for RNA transcription of E. Coli (4 points)? (c) Please explain why DNA polymerases and RNA polymerases have significant different rates (2 points)

Explanation / Answer

E.coli genome bp=5,000,000

Time needed for to replicate whole DNA=3000s

Rate of replication= one replication/3000s

Rate of replication=5000000/3000s

Rate of replication=1666.66bp/second

Length of RNA transcript=1000bases

Time taken=25 seconds

Rate=1000/25= 40bases/second

DNA polymerase and RNA polymerase have different rates due to the fact that both have different functions. Where formers has to double the DNA in S phase before cell divides and the latter has to make mRNA which is latter used proteins for the maintaince of cell growth and life and also Rrna and tRNA as adaptor molecules