Explain the roles of helicase and polymerase in DNA replication.
helicase unwinds the dna so that the dna can be replicated
the polymerase "reads" an intact DNA strand as a template and uses it to synthesize the new strand.
Thanks Betty! :)
Helicase and polymerase play crucial roles in DNA replication, a process by which a cell creates an identical copy of its DNA during cell division.
Helicase is an enzyme that unwinds the double-stranded DNA molecule by breaking the hydrogen bonds between the base pairs. This unwinding creates a replication fork, which is the point where the two strands of the DNA molecule separate. Helicase moves along the DNA strand, continuously separating the two strands and exposing the template strands needed for replication.
To understand the role of polymerase, it is important to note that DNA molecules are composed of two complementary strands. Each strand serves as a template for the synthesis of a new complementary strand during replication. Polymerase, specifically DNA polymerase, is an enzyme that adds new nucleotides to the growing DNA chain. It can only add nucleotides in the 5' to 3' direction.
During replication, DNA polymerase moves along the exposed template strand in the 3' to 5' direction, adding complementary nucleotides to synthesize new DNA strands. However, since DNA polymerase can only add nucleotides in the 5' to 3' direction, it can only add new nucleotides to the growing strand in one direction (3' to 5').
This creates a challenge because the two DNA strands are oriented in opposite directions. The leading strand can be synthesized continuously in the same direction as the replication fork advances, while the lagging strand is synthesized in small fragments, called Okazaki fragments, in the opposite direction. DNA polymerase works in coordination with other enzymes to synthesize these Okazaki fragments, and later, another enzyme called DNA ligase helps to join the fragments together.
In summary, helicase unwinds the DNA molecule and creates a replication fork, while DNA polymerase adds new nucleotides to synthesize new DNA strands. Helicase separates the two template strands, and DNA polymerase uses these templates to create new complementary strands during replication.