Basics of DNA Replication (Genetics)

 

As a whole, there are three main steps/stages of DNA replication: initiation,

elongation, and termination. The initiation stage is where DNA replication is

initiated: within the template strand in a coding region site known as origins. More

importantly, there are several of these origin sites, they are acknowledged as

replication forks: this is where the double helix will be separated. As a result, DNA

helicase unwinds the double helix. Thus, the separation preps DNA polymerase and

other enzymes to synthesize a new double helix: by growing a new DNA daughter

strand. During the process of elongation, DNA polymerase adds DNA nucleotides to

the 3’ end of the synthesized polynucleotide strand. As a result, the new strand will

be synthesized in the 5’ to 3’ direction, this strand will be known as the leading

strand. In the process, DNA primase synthesizes a RNA primer, initiating DNA

polymerase to continue developing new nucleotides. As a result, the new DNA strand

extends/elongates. In correspondence, the 5’ to 3’ template is also elongated forming

a lagging strand (which is replicated in the opposing direction of the replication

fork). As a result, DNA is added to the lagging strand in a discontinuous form,

known as Okazaki fragments. The last step in the DNA replication process,

termination, occurs when two of the replication forks meet. For instance, after the

creation and extension of leading and lagging strands, initiates exonuclease: an

enzyme that removes all RNA primers from original strands. Additionally, another

form of the enzyme proofreads the strands, fixing any errors made in the process.

Moreover, some of the more recognizable enzymes and proteins involved in DNA replication are: DNA Polymerase, Helicase, SSB (single-stranded DNA-binding Proteins), Primase, DNA Ligase, DNA Topoisomerase, and Telomerase. For instance, DNA Polymerase, is involved with Primase activity, gap filling and synthesis of lagging strand, DNA proof reading and repair(Epsilon), DNA repair(Beta), mitochondrial DNA synthesis(Gamma). As well as, the synthesis of the leading DNA strand (Delta). Whereas, Helicase is involved in the unwinding of DNA double helix. SSBs, single stranded DNA-binding proteins, stabilize unwound strands. Alternatively, the synthesis of RNA primers is regulated by Primase.


All in all, the process of DNA replication is a complex mechanism where the genome's DNA is replicated in cells. For instance, before cell division, replication of DNA must take place. As a result, the resulting daughter cells will have their own copy of the replicated DNA.


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