Question

5. DNA replication of the circular chromosome in E. coli begins when a protein called DnaA binds to the replication origin on the DNA. The replication origin likely to be richer in the nucleotides _______ and ________, thereby making it easier to separate the strands during replication. 6. Explain your answer.

Answer 1

Adenine; Thymine

Step-by-step explanation:

• The origin of replication in E.coli is called the oriC
• This region is rich in Adenine and Thymine bases because their base stacking interactions are weaker than those of Cytosine and Guanine.
• Between A and T bases there are only 2 hydrogen bonds (not a very strong interaction so requires less energy to separate) while between C and G bases there are 3 hydrogen bonds (strong interaction thus requires more energy to separate)
• The oriC is a region which needs to be separated when replication occurs. It is thus a region which requires easy separation with as little energy as possible so that proteins like DnaA can bind.