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What is the difference between continuous and discontinuous DNA synthesis?

Science 2021

The genetic code of living organisms is contained in the DNA of the chromium zoom. Since the DNA molecule has a double helix made up of pairs of nucleotides, each consisting of a phosphate group, a sugar group


The genetic code of living organisms is contained in the DNA of the chromosomes. The DNA molecule is a double helix made up of pairs of Nucleotideseach consisting of a phosphate group, a sugar group and a nitrogen base. The structure of the nucleotides is asymmetrical, which means that the two strands of double helix DNA have opposite directions.

When DNA synthesis occurs during DNA replication, the two strands of the double helix become separated. Replication can only occur in the forward direction of each strand. As a result, one strand is copied continuously in the forward direction while the other is copied discontinuously in segments that are later joined together.

Why the strands of DNA have a direction

The sides of the double helix DNA molecules are made up of Phosphate and sugar groups while the sprouts are made up nitrogenous bases. Usually the carbon atoms in the carbon chains or rings of organic molecules are numbered sequentially. The carbon atoms in the nitrogenous bases are numbered 1, 2, 3, and so on. To distinguish the numbered carbon atoms of the sugar groups, these carbon atoms are numbered with a prime number symbol, i.e. 1, 2, 3 etc. or a prime number etc.

There are five carbon atoms in the sugar groups numbered 1 through 5. The 5 atom has a Phosphate group attached to it while the 3 carbon compounds become one OH group. To form the sides of the helix, the 5-phosphate on one side of the sugar group combines with the 3-OH on the next nucleotide. The order of this strand is 5 to 3.

The rungs of the helix molecule are formed from linked nitrogenous bases. The four bases in DNA molecules are adenine, guanine, cytosine, and thymine, abbreviated as A, G, C, and T. The A and T bases can form a link, and G and C can form a link.

If a nucleotide in the 5- to 3-chain sequence is linked to another nucleotide to form a rung, the other nucleotide has the opposite phosphate / OH sequence. This means that one side of the helix is ​​in the direction of 5 to 3 while the other side is in the direction of 5 to 3 3 to 5 Direction.

Discontinuous DNA replication versus continuous replication

DNA synthesis can only take place when the two strands of the double helix are separated. During DNA replication, an enzyme breaks the helix and opens up DNA polymerase copies every strand. The strand running in the 5 to 3 direction is called the leading strand, while the other strand with a sequence of 3 to 5 is the trailing strand.

The polymerase can only copy DNA into DNA 5 to 3 direction. This means that it can continuously replicate the leading strand as it moves along the strand from the starting point of the separation. In order to copy the trailing strand, the polymerase must replicate backwards along the strand to the initial point of separation.

The replication is then stopped, the strand is shifted upwards and there is a switch backwards to the segment that was already copied. A number of separate DNA segment copies are called Okazaki fragments are made from the tail line.

DNA ligase

As DNA replication proceeds, the DNA ligase enzyme connects the Okazaki fragments into one continuous strand. This combination of continuous synthesis of the leading strand and piecewise or discontinuous replication of the trailing strand results in two new DNA helixes as soon as the segments of the trailing strand are connected.

Each new double helix has a parent strand from the original DNA molecule and a newly replicated strand that is synthesized by DNA polymerase. When replication was successfully completed, there is no difference between the two copies of the original DNA molecule, although one was derived from continuous replication while the other had discontinuous DNA replication.

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