What Is DNA And What Does It Do?

An in depth explanation of what DNA is and how it replicates!

Let us zoom into the cellular world, first looking at chromosomes, which house genes, which contain the infamous DNA. DNA stands for deoxyribonucleic acid. A DNA molecule consists of two strands of nucleotide sequences, held together by hydrogen bonds. These two strands are twisted like a spiral staircase in a double helix. The nucleotides which are on the sequences are: cytosine, thymine, adenine, guanine. Cytosine and guanine form three hydrogen bonds, while adenine and thymine only form two hydrogen bonds. Adenine and thymine are part of the purine group, while cytosine and guanine are part of the pyrimidine.

Despite the fact that they bonds aren't equal, the base pairs are all of the same width. This is vital for keeping the sugar phosphate backbone and equal distance apart at all points.

These nucleotides are on the inside of the helix. On the outside of the helix is a alternation pattern of the five carbon sugar deoxyribose, and phosphate groups. The nucleotides are covalently linked onto the sugar phosphate.



DNA strands run antiparrallel. In this I mean they always run, or are copied, from 5' to 3'. So while on the right you might have the 5¡¦ end, on the other side there is the 3'. This is due to the polarity signified by the carbon structure.

DNA carries genetic information that is copied when a cell divides. The way with which the nucleotides are ordered, determines the genetic information, it is a form of language. Specifically, it is a language which dictates protein synthesis. The whole of the DNA information is titled the genome.

As just mentioned, DNA must replicate in order to pass on it¡¦s information, this is titled DNA replication. In DNA replication, one strand of DNA must be the template. This strand of DNA is then copied in the 5' to 3' direction. All of the nucleotides are paired with a complementary nucleotide. Then you will eventually have two identical DNA double helices. Each of the new helices will contain one of the strands from the original DNA molecule.

DNA replication starts at several different origins in order to speed up the process. These points of origin later become Y-shaped replication forks which are going in two directions at once (remember they must always go 5' "ž³ 3'). The synthesis of the actual DNA is carried out by an enzyme titled DNA polymerase.

After synthesis is complete, the DNA polymerase carries out proofreading, where it checks to make sure are nucleotides are correctly paired. If there is an error, it cuts the phosphodiester bond between the two nucleotides and replaces the nucleotide on the new strand. If it replaced the nucleotide on the old strand, the genetic information would be permanently altered. A new strand of DNA can't be made in the same fashion as detailed above. In stead, RNA (ribonucleic acid) primers are necessary.

DNA replication is a vital process in all life. In order for reproduction to properly occur, the DNA must be replicated and passed on to offspring. It is for this reason that there are fewer than 1 in 10,000,000 errors in DNA replication.

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