Explain the roles of specific enzymes in prokaryote DNA replication. [7 marks]

DNA replication is the same in eukaryotes and prokaryotes; the question just emphasizes that the process depends on enzymes and their functions need to be explained.DNA gyrase (or topoisomerase II) relieves the strains on the double helix, facilitating uncoiling of DNA. Helicase unwinds the DNA double helix by breaking the hydrogen bonds between the linked base pairs in the two strands. DNA primase adds a small RNA sequence at the 5' end of the strand that is being replicated to initiate the activity of DNA polymerase (III). DNA polymerase III recognizes the RNA primer and adds the complementary (deoxyribo)nucleotides in a 5'-3' direction, thus synthesizing the complementary DNA strand. DNA polymerase I is responsible for removing the short RNA primer sequence needed for replication initiation. DNA polymerases III and I both proofread the DNA newly-formed strand by taking part in the previously described processes. Since in the lagging strand the DNA replication happens in fragments (the Okazaki fragments), DNA ligase is an enzyme that will link these small sections of replicated DNA (or otherwise ligase seals the nicks).

HS
Answered by Hristo S. Biology tutor

6007 Views

See similar Biology IB tutors

Related Biology IB answers

All answers ▸

State one similarity and one difference between homologous chromosomes.


What is the protein synthesis pathway in the cell?


What are the similarities and differences between mitosis and meiosis?


Explain that female carriers are heterozygous for X-linked recessive alleles.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences