Genetics: Analysis and Principles 5th Edition by Robert Brooker

تمرين 40

As shown in Figure 11.5, five DnaA boxes are found within the origin of replication in E. coli. Take a look at these five sequences carefully
a. Are the sequences of the five DnaA boxes very similar to each other (Hint: Remember that DNA is double-stranded; think about these sequences in the forward and reverse direction.)
B. What is the most common sequence for the DnaA box In other words, what is the most common base in the first position, second position, and so on until the ninth position The most common sequence is called the consensus sequence
c. The E. coli chromosome is about 4.6 million bp long. Based on random chance, is it likely that the consensus sequence for a DnaA box occurs elsewhere in the E. coli chromosome If so, why aren't there multiple origins of replication in E. coli
FIGURE 11.5 The sequence of oriC in E. coli. The AT-rich region is composed of three similar sequences that are 13 bp long and highlighted in blue. The five DnaA boxes are highlighted in orange. The GATC methylation sites are underlined.