How Many Strands Of Dna Are Used As The Template In Dna Replication

We know that DNA is a self-replicating structure and Dna replicates semi-conservatively. However, DNA replication is catalyzed by a set of enzymes. Let's acquire about the DNA replication process and the role of enzymes involved in DNA replication.

Dna Replication

In the process of Dna replication, the DNA makes multiple copies of itself. It is a biological polymerisation, which proceeds in the sequence of initiation, elongation, and termination. Information technology is an enzyme-catalysed reaction. DNA Polymerase is the main enzyme in the replication process.

Machinery and Enzymes of DNA replication

DNA Replication Process

DNA Replication Steps

Following are the important steps involved in DNA replication:

Initiation

DNA replication demands a high caste of accurateness because even a minute mistake would upshot in mutations. Thus, replication cannot initiate randomly at any point in Dna.

For the replication to begin there is a particular region chosen the origin of replication. This is the betoken where the replication originates. Replication begins with the spotting of this origin followed by the unwinding of the two DNA strands.

Unzipping of Dna strands in their entire length is not feasible due to high energy input. Hence, outset, a replication fork is created catalysed by the helicase enzyme, which unzips the Deoxyribonucleic acid strand.

Elongation

Every bit the strands are separated, the polymerase enzymes start synthesising the complementary sequence in each of the strands. The parental strands will act as a template for newly synthesising girl strands.

It is to be noted that elongation is unidirectional i.e. DNA is always polymerised only in the 5′ to iii′ direction. Therefore, in one strand (the template three'→5') information technology is continuous, hence called continuous replication while on the other strand (the template 5'→three') information technology is discontinuous replication. They occur as fragments called Okazaki fragments. The enzyme called DNA ligase joins them later.

Replication fork

Dna Replication Fork

Termination

Termination of replication occurs in different ways in dissimilar organisms. In E.coli like organisms, chromosomes are circular. And this happens when the 2 replication forks between the ii terminals meet each other.

As well Read:DNA Structure

Function of Enzymes in Dna Replication

DNA replication is a highly enzyme-dependent process. There are many enzymes involved in DNA replication, which includes the enzymes, Dna-dependent DNA polymerase, helicase, ligase, etc. Amid them, DNA-dependent Dna polymerase is the main enzyme.

Deoxyribonucleic acid-dependent DNA polymerase

It helps in the polymerisation, catalyses and regularises the whole process of DNA replication with the support of other enzymes. Deoxyribonucleoside triphosphates are the substrate also as the energy provider for the replication process. DNA polymerase is of three types:

DNA Polymerase I

It is a Dna repair enzyme. It is involved in three activities:

5′-three′ polymerase activity
five′-3′ exonuclease activeness
3′-5′ exonuclease action

DNA Polymerase II

Information technology is responsible for primer extension and proofreading.

DNA Polymerase III

It is responsible for in vivo Dna replication.

Helicase

Helicase is the enzyme, which unzips the DNA strands by breaking the hydrogen bonds betwixt them. Thus, information technology helps in the formation of the replication fork.

Ligase

Ligase is the enzyme which joins together the Okazaki fragments of the discontinuous Dna strands.

Primase

This enzyme helps in the synthesis of RNA primer complementary to the DNA template strand.

Endonucleases

These produce a single-stranded or a double-stranded cut in a DNA molecule.

Unmarried-stranded Binding Proteins

It binds to single-stranded Deoxyribonucleic acid and protects it from forming secondary structures.

Besides Read:Difference between Replication and Transcription

DNA Replication Process in Prokaryotes

The DNA replication in prokaryotes takes place in the following identify:

The ii strands of DNA unwind at the origin of replication.
Helicase opens the Dna and replication forks are formed.
The Deoxyribonucleic acid is coated by the unmarried-strand binding proteins around the replication fork to prevent rewinding of Deoxyribonucleic acid.
Topoisomerase prevents the supercoiling of DNA.
RNA primers are synthesised by primase. These primers are complementary to the Dna strand.
DNA polymerase Iii starts calculation nucleotides at the end of the primers.
The leading and lagging strands continue to elongate.
The primers are removed and the gaps are filled with DNA Polymerase I and sealed by ligase.

DNA Replication in Eukaryotes

The Dna replication in eukaryotes is similar to the Dna replication in prokaryotes. Even so, the initiation process is more complex in eukaryotes than prokaryotes. In eukaryotes, there are multiple origins of replication present. A pre-replication complex is fabricated with other initiator proteins. The process is entirely the aforementioned but the enzymes used are different. E.k. in eukaryotes, the polymerisation process is carried out by the enzyme Pol δ, whereas in prokaryotes information technology is done by Deoxyribonucleic acid Pol III.

Likewise Read:Dna Packaging

For more information on the Dna replication procedure in prokaryotes and eukaryotes and the steps involved in DNA replication, keep visiting BYJU'S website or download BYJU'South app for farther reference.