Q. 164.8( 6 Votes )

Explain the mecha

Answer :


Mechanism of DNA replication:


i. Initiation –


There is a particular region called origin of replication. This is the point where the replication originates.


The DNA strands are unwound to form a replication fork. This is created by polymerases enzyme which is an opening in the DNA strand.


ii. Elongation –


As the strands are separated, the polymerase enzymes start synthesizing the complementary sequence in each of the strands.


The parental strands will act as a template


Elongation is unidirectional i.e. DNA is always polymerized only in the 5′ to 3′ direction.


In one strand (the template 35) it is continuous, hence called continuous replication while on the other strand (the template 53) it is discontinuous replication. They occur as fragments called Okazaki fragments.


DNA ligase joins these fragments later on.


iii. Termination –


The termination occurs in different ways in different organisms.


In E.coli like organisms, chromosomes are circular. And this happens when the two replication forks between the two terminals meet each other.


DNA - Ligase is the enzyme which glues the discontinuous DNA strands (OKAZAKI FRAGMENTS)


OR


RNA molecule doesn’t contain Thymine (T). Hence the question is wrong.


Assuming the correct sequence was the given, the question would be solved like this:


The correct RNA segment should be


5’ A U G C A U G C A U G C 3’


3’ U A C G U A C G U A C G 5’


The process of copying genetic information from strand of DNA into RNA is known as transcription.


The transcription unit for the above mentioned RNA molecules would be like this:



The enzyme that transcribes this RNA is DNA-dependant RNA polymerase.

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