Nucleic Acid Components and Functions, Biology tutorial


The nucleic acids (DNA and RNA) are wonderful discoveries of the recent times. They are generally present in the nucleus and in the cytoplasm of all the living cells and are now definitely recognized to form the chemical basis of life.

Nucleic Acid Components:

Adenine, cytosine, guanine and phosphate group are general to both RNA and DNA. Ribose sugar and uracil are obtained in RNA whereas thymine and deoxyribose are in the DNA.

1) Nucleobases:

Nucleobases are heterocyclic aromatic organic compounds having nitrogen atoms. Nucleobases are portions of RNA and DNA engaged in base pairing. Cytosine, adenine, guanine, thymine are found mostly in DNA, whereas in RNA uracil substitutes thymine. These are abbreviated as C, G, A, T, U, correspondingly.

Nucleobases are complementary and whenever making base pairs should always join accordingly: cytosine-guanine, adenine-thymine (adenine-uracil if RNA). The strength of the interaction among cytosine and guanine is stronger than among adenine and thymine as the former pair consists of three hydrogen bonds joining them whereas the latter pair consists of just two. Therefore, the higher the GC content of double-stranded DNA, the more stable the molecule and the higher the melting temperature.

2) Nucleosides:

Nucleosides are the glycosylamines build up by joining a nucleobase (simply termed as bases) to a ribose or deoxyribose (sugar) ring. In short, a nucleoside is a base linked to the sugar. The names obtain from the nucleobase names. The nucleosides generally occurring in DNA and RNA comprise cytidine, uridine, adenosine, guanosine and thymidine. If phosphate is added to a nucleoside (through a specific kinase enzyme) a nucleotide is generated. 

3) Nucleotides:

A nucleotide comprises of a nucleoside and one phosphate group. Nucleotides are the monomers of RNA and DNA and also forming the structural units of some significant cofactors - CoA, flavin adenine dinucleotide, flavin mononucleotide, adenosine triphosphate and nicotinamide adenine dinucleotide phosphate. In cell nucleotides play significant roles in metabolism and signaling.

Nucleotides are termed after the nucleoside on which they are based, in conjunction by the number of phosphates they contain. For illustration: adenine bonded to ribose forms the nucleoside adenosine. Adenosine bonded to the phosphate forms adenosine monophosphate. As phosphates are added, adenosine diphosphate and adenosine triphosphate are made, in series. The ATP, adenosine triphosphate is a nucleotide.

Functions of Nucleic Acids:

The major function of nucleic acids is to store and transmit genetic information and utilized that information to direct the synthesis of new protein. The DNA (that is, deoxyribonucleic acid) is the permanent storage place for genetic information in the nucleus of the cell. DNA controls the synthesis of RNA (that is, ribonucleic acid). RNA transmits genetic information from DNA to the protein synthesizers in the cell. RNA is as well responsible for directing the production of the new protein through transmitting the genetic information to the protein building structures. The nucleotide, ATP (that is, adenosine triphosphate) that is closely associated to DNA and RNA, is the short-term energy storage for all the life processes. The function of the series of bases (that is, adenine, cytosine, guanine and thymine) in the backbone of DNA finds out what proteins are being synthesized and in what order (note that in RNA, thymine is substituted by uracil).  The function of the double helix formation of DNA molecules is to make sure that no disorders take place when genetic information is lost or damaged. Illustrations of disorders associated to damaged or lost genetic information are sickle cell anemia and Down's syndrome.

Functions of DNA (Deoxyribonucleic Acid):

a) DNA is a permanent storage position for the genetic information.

b) DNA controls the synthesis of the ribonucleic acid (RNA).

c) The series of nitrogenous bases in DNA finds out the protein growth in new cells.

d) The function of the double helix formation of DNA is to make sure that no disorders takes place. This is because the second similar strand of DNA which runs anti-parallel to the first is a backup in case of lost or damaged genetic information. 

Functions of RNA (Ribonucleic Acid):

a) RNA is synthesized through DNA for the transportation of genetic information to the protein making apparatus in the cell.

b) RNA as well directs the synthesis of new proteins by employing the genetic information it has transported.

c) mRNA (that is, messenger ribonucleic acid) is employed to transfer genetic information via plasma membranes.

Functions of some Nucleotides:

a) The nucleotide, adenosine triphosphate (ATP) is the short-term energy storage for all the living organisms. Nucleic acids can be employed to make energy in the form of ATP.  ATP is build up with the nitrogenous bases ribose and adenosine. 

b) Three phosphates are joined with the above nitrogenous bases to make ATP.  But how does ATP give the energy? To give energy, ATP goes via the procedure of hydrolysis, producing energy, and also a phosphate molecule.

c) It is significant to note that, throughout cellular respiration, ATP can be accessed either via aerobic (having oxygen) system and anaerobic (devoid of oxygen) system. Aerobic access of ATP energy is much more proficient, making 36 ATP rather than 2 with anaerobic.

d) CAMP (that is, cyclic adenosine monophosphate) is a messenger in the hormone regulation.

e) Nucleotide derivatives like NAD + (that is, nictinamide adenine dinucleotide) are employed as a coenzyme in the photosynthesis.

Duplication Abilities of RNA and DNA:

Nucleic acids (in particular DNA) carry out an essential role in the human body. Especially, nucleic acids play a vital role in both mitosis and meiosis.

In mitosis, the chromosomes and genetic information contained within the nucleus of the parent cell is duplicated. The two resultant daughter cells have similar genetic information to the parent cell. This is possible just via nucleic acids remarkable capability to make similar copies of itself. This is the only molecule known to encompass this capability. Mitosis is necessary to life as it substitutes damaged or dead cells, repairs tissues and lets the body to grow (in size and mass).

The other use for nucleic acids duplication capability is meiosis. Meiosis is the procedure in which sex cells are made. Devoid of nucleic acids, meiosis would be impossible and thus there would be no reproductive procedures in the living organisms.

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