9+ Function of Cytosine: Why, How and Detailed facts

Cytosine is considered one among the nucleotides bases in both of the nucleic acids mainly DNA and RNA.

Cytosine is of the four bases in DNA and RNA with the function of cytosine being controlling of the hereditary material for the living cells and also in some serving as a coenzyme that shall act in conjunction with the enzymes in body.

The bases can be a derivative of both pyrimidine and purine. Cytosine on the other hand is a derivative of pyrimidine along with thymine or uracil and is seemed to be an aromatic heterocyclic ring which have two of the substitutes linked up. There is an amine group attached at the 4th place and a keto group linked at the second position.

Cytosine is a pair of guanine and is vital in playing a metabolite for human. It is a metabolite of the Escherichia coli and a referral for mouse metabolite along with also for Saccharomyces cerevisiae. Cytosine helps in controlling many of the work in chemical reaction and getting data changed.

All of the bases do have a nucleoside of their own and the one for cytosine is called the cytidine. Considering the function of cytosine and the base pairing in the model of Watson and Crick, cytosine is seen to make there of the hydrogen bonds along with another base called the guanine that is the purine derivative. Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone.

Cytosine can be found as a portion of DNA or RNA or even as a portion of any nucleotide. As a part of cytidine triphsophate it can play a part of co enzyme and can let the start for conversion of adenosine diphosphate to adenosine triphosphate. Cytosine is seemed to pair up with guanine in both the acids. In organic chemistry, a substituent is an atom or group of atoms substituted in place of a hydrogen atom on the parent chain of a hydrocarbon.

function of cytosine
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Structure of Cytosine

As a base of nitrogen, cytosine is made of three of the nitrogen atoms. It is also made of one carbon ring that makes it is a base of pyrimidine.

On the other hand purine is made of two carbon rings. Cytosine is referred to as pyrimidine along with thymine in DNA and the rest two are stated to be purine in DNA. RNA also has two of the pyrimidine, they are uracil and cytosine.

Inside the DNA the base of thymine and adenine are there in similar percentage and do always link together with each other. It then leaves the rest of them being cytosine to pair up with the guanine which is a double ring structure. Cytosine pairs with guanine in both DNA and RNA. Cytosine can sometimes loose electrons by mistake and become uracil. This is known as spontaneous deamination. If DNA repair enzymes such as uracil glycosylase do not repair the damage by cleaving uracil in DNA, a point mutation may result.

Adenine (A) and Guanine (G) both have a double ring structure and are called purines. Thymine (T) and Cytosine (C) both have a single ring structure and are called pyrimidines. Because of their structural similarity, we usually refer the nine-member double rings adenine and guanine as purines, and six-member single-ring thymine, uracil, and cytosine are pyrimidines.

At the time when cytosine is one of the strands in the nucleic acid, the rest of the strands will be definite in having guanine to show up its bond and match. They are companions as they fit perfect collaborating with three bonds of hydrogen. Cytosine can also transfer easily into other bases and thus call the wild card base. Nucleotides containing cytosine can power chemical reactions and are involved in signaling inside the cell.

DNA is said to store information that helps in making and building of the cell. The transmission of the code is a task and the data for all the genetic transfer is stored in cytosine. It is replicated while the cell gets a duplicate copy and then makes the cell to divide. Heterocyclic compounds are organic compounds (those containing carbon) that contain a ring structure containing atoms in addition to carbon—such as sulfur, oxygen, or nitrogen—as part of the ring.

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Heterocyclic compoundsWikipedia

Function of cytosine

In the meteorites, there has been no traces of the base cytosine and thus its suggestion states that the first stands of the DNA or RNA had to be seen else to take the building block. 

Cytosine can be said to be a part of the nucleotide which is a molecule having a sugar and one or more of the phosphates. The time when the nucleotide gets connected they form the DNA and RNA said to the nucleic acids.

Cytosine recently found use in quantum computation. The first time any quantum mechanical properties were harnessed to process information took place on August 1st. It is termed to be a third in terms of codon in the RNA, cytosine is the synonym for uracil and are said to be interchangeable as known for its third base. When it is found to be in the second position in any codon, it is changeable.

An example for this can said to be UCU, the UCG, UCA and UCC and all of them are serine despite any one of them being the third base. There is also an enzymatic deamination that is active in the cytosine. Cytosine can be said to be 5-methycytosine by the APOBEC family of the cytosine. Cytosine-C5 DNA MTases catalyze the transfer of the methyl group from a cofactor molecule S-adenosyl-l-methionine. Purine biosynthesis differs from pyrimidine biosynthesis in that purines are formed first as a nucleotide, whereas pyrimidines are formed first as a free base

Codon in genetics is a rule set that is utilized for all the living ce;;s to convert the information encoded inside the genetic material and convert into proteins. The transfer in obtained by ribosome that links to the protein genic amino acid that is specific to the messenger RNA and uses the transfer RNA to carry them. Cytosine undergoing modifications are often located in clusters which are therefore repetitive in nature. Short-read based methods are unable to uniquely map short reads to repetitive regions, resulting in the under representation of these important regions.

It can be both useful and harmful for all the implications imposed on several processes of the cell as well as for the evolution in the organism. The outcome of the deamination onto the 5-hydromethylcytosine on the rest part seems to be hard and harmful to deal with. The coding of it is same to that of the entire organism. It is a pyrimidine base C4H5N3O that codes genetic information in the polynucleotide chain of DNA or RNA — compare adenine, guanine, thymine, uracil.

Image credit- Messenger RNAWikipedia

The function of cytosine is-

  • Each of the cytosine takes part in building of code for the cell
  • It links with the other side guanine base and can also get itself changed to uracil. Cytosine forms three hydrogen bonds with guanine in DNA and RNA. This device, however, is unstable and can transform into uracil.
  • Mostly inside the cell cytosine has a linked up extra group of methyl as a chemical
  • They can also get into modifying of its bases that shall carry the epigenetic data.
  • It can also be a carrier in having their energy carried out and also being a cofactor of CTP.
  • Cytosine can help carry the genetic data for the molecules they have.
  • Aromaticity is a chemical property in which the stability of a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals is greater than can be predicted from conjugation alone.
  • Cytosine forms the nucleoside cytidine when it binds to ribose, and deoxyribose forms deoxycytidine when it binds to deoxyribose.
  • The methylation of this in cytosine is said to get the genes regulated to help them turn themselves on and off whenever needed.
  • It’s a pyrimidine nucleobase, pyrimidone, and aminopyrimidine all rolled into one. The molecule has a planar shape, and in the DNA double helix, cytosine forms three hydrogen bonds with Guanine


I am Ankita Chattopadhyay from Kharagpur. I have completed my BTech in Biotechnology from Amity University Kolkata. I am a Subject Matter Expert in Biotechnology and also a web content writer (freelancer). I have been keen in writing articles and also interested in Literature with having my writing published in a Biotech website and a book respectively. Along with these, I am also a Hodophile, a Cinephile and a foodie.

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