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Hi friends, in this tutorial we are going to discuss about the difference between
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prokaryotic and eukaryotic DNA replication. First of all, let us start with an
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introduction about the DNA. DNA is a genetic material in all organisms from
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bacteria to blue whale and it performs two important functions to make it as a
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genetic material. First is the autokaryotic function where it directs its own
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synthesis or making copies of itself. Second is a hetero karyotic function
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where it directs the synthesis of RNA and proteins altogether forming the
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central dogma of biology where the DNA directs the synthesis of proteins. Now
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moving into the difference between the prokaryotic and eukaryotic replication difference number one is regarding the site of DNA replication. In prokaryotes
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DNA replication occurs in the cytoplasm whereas in eukaryotes the site of DNA
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replication is a nucleus. Difference number two in prokaryotes DNA replication occurs in connection with the cell division or it is a first step in binary
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vision or budding. Whereas in the case of eukaryotes it is a complex process in
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the cell cycle DNA replication occurs during the synthesis phase that is the S
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phase of the cell cycle. Difference number three is regarding the ORI. ORI is
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the origin of replication or a specific sequence that is required to initiate DNA
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replication. In the case of prokaryotes there is a single ri per DNA molecule. In
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the case of eukaryotes the genome is simple single circular circular DNA
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molecule and it is very comparatively less amount of DNA compared to the eukaryotic system and replication of DNA occurs at a single point in prokaryotic DNA molecule whereas in the case of eukaryotes the genome is very vast 50 or more times larger than that of
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the prokaryotic system so that there are number of ORIs many ORIs are present you can see these are
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the origin of replications where the DNA replication starts thousands of ORIs in each
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eukaryotic chromosome and replication occurs at several points in all these ORIs simultaneously in order to replicate this large amount of DNA now the
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difference number four it is regarding the number of nucleotides in the ORI in
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the case of prokaryotes this ORI is formed of approximately 100 to 200 or
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more nucleotides whereas in the case of eukaryotes each ORI is formed of
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approximately 150 nucleotides difference number five it is regarding the formation of replication fork. In the case of prokaryotes these are the replication fork that
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is formed as a result of unwinding of the DNA strand by the helicase enzyme. In the case of
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prokaryotes there are two replication forks and a single replication bubble. This structure is
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called as a replication bubble. As the DNA replication is bidirectional a bubble formation
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occurs. There are two replication forks and a single bubble in the case of prokaryotic DNA
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replication whereas in the case of eukaryotes a number of replication folks
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you can see right here a number of ORIs so that so that a number of replication
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many replication folks are present and also a number of bubbles are present in
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order to replicate simultaneously all these origin of replication regions now the difference number six it is regarding the number of replicons a replicons is a part of ORI along with the part of the DNA that is to be replicated in the case of prokaryotic system there is a single replicons that
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is the entire DNA is replicated simultaneously on a single stretch so
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prokaryotic chromosome has one replicons but as in the case of eukaryotes a
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number of replicons is present and these replicons may not be replicating
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simultaneously at a time maybe a different replicant may be replicating a different time now the difference number seven this is
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regarding the initiation in initiation of dna replication in prokaryotes is carried out by protein proteins like tna a p etc
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and many other proteins whereas in the case of eukaryotes initiation of dna
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replication is carried out by a multi-subunit protein complex it is often called as origin recognition complex a number of proteins are
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in fault in order to initiate the DNA replication. Difference number eight it
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is regarding the DNA polymerase. As we know in DNA replication there are
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two strands synthesis. One is a leading strand which is synthesized continuously whereas the second one is a lagging strand which is synthesized as
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short fragments called as okasaki fragments. In prokaryotes this leading strand and lagging strand both are synthesized by the enzyme DNA polymerase
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3 whereas in the case of eukaryotes this leading strand is synthesized by DNA
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polymerase delta and lagging strand is synthesized by DNA polymerase alpha difference number 9 it is regarding the size of the Okasaki fragments in the
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case of lagging strands the DNA is synthesized as short stretches called as Okasaki fragments and these Akasaki fragments the size of these Akasaki fragments in prokaryotes is approximately thousand to two thousand nucleotides whereas in the case of
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eukaryotes it is much shorter it is 100 to 200 nucleotides long difference
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number 10 in the case of prokaryotic DNA replication it's very fast rapid
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compared to eukaryotic replication 200 base pairs per second as the genome size
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is very small and there is not much requirement of a fidelity as it is a
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single-celled organism a mutation may not affect much whereas in the case of
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eukaryotes comparatively it is a slow process 100 nucleotides per second but
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remember it is a large genome so that a number of ORI origin of replication or
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replicon is working together to synthesize all this DNA to copy all this
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DNA difference number 11 it is regarding the termination of DNA replication now
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telomerase or specific there is a specific termination sites or tercide specific sequences
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where the DNA replication stops as in the case of prokaryotes it is circular DNA molecule at the
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end there will be a daughter strand and the parental strand that is interlocked and this
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locking is unlocked by the enzyme top isomerase 2 but in the case of eukaryotes as the eukaryotic
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chromosome is linear it involves synthesis of specialized structures called telomeres at the
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end there is a telomere there is an end replication problem that is that is sorted out by an enzyme
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called as telomerase and it is an elaborate process also and we have discussed all the
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major differences between eukaryotic and prokaryotic tna replication hope things are clear if you like
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this video please share and like thank you so much for watching you are with biologics i'm sorry dot com
