Question

Replication of the genome is a key step in the reproduction of an organism. Compare and contrast the process of genome replication in E. coli with that of SARS-Cov-2 (the virus that causes COVID-19) . For full credit, please provide at least two similarities and two differences.

Answer 1

Genome replication in SARS-Cov-2:

· SARS-Cov-2 genome replication involves a linear single-stranded positive RNA genome of 265 basepairs.

· RNA replication involves two RNA-dependent RNA polymerases, in which, one RNA polymerase namely, non-structural protein 12 (nsp12), requires primer for RNA replication, whereas the second RNA polymerase, non-structural protein 8 (nsp8), does not require a primer for RNA replication.

· Nsp 8 protein along with Nsp 7 forms a complex multimeric RNA polymerase that helps in initiation and primer extension of RNA replication without a primer.

Genome replication in E.coli

· E. coli contains a single stranded DNA molecule with 4.6 million basepairs

· The DNA replication occurs in two directions with the formation of two replication fork.

· There occurs synthesis of two nascent DNA strands, one on leading strand which is continuous and another on lagging strand which is discontinuous.

· The synthesis of DNA strands occurs on a same replication apparatus called as replisomes.

Similarities between E.coli and SARS-Cov-2 genome replication

1. Both E. coli and SARS-Cov-2 genomes are single stranded

2. Genome replication requires primers for the replication process.

3. Both forms replication machinery for the genome synthesis.

Differences between E.coli and SARS-Cov-2 genome replication

1. E. coli genome is single stranded DNA whereas that of SARS-Cov-2 is single stranded RNA

2. E.coli requires DNA polymerase for DNA replication whereas SARS-Cov-2 requires RNA dependent RNA polymerase for replication.

3. Primers are essential for E. coli DNA replication whereas one RNA polymerase nsp 8 of SARS-Cov-2 can replicate RNA without primers.