Roles of dna and rna, Biology tutorial


Like any other macromolecule discovered in living systems, nucleic acid have their roles and functions wherever they are found. Aside from fact that nucleic acids vary from one another structurally and chemically, they also have various functions and roles which is very much reflected in chemistry.

Difference between DNA and RNA:

Though both deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are nucleic acids, they yet have few differences chemically and structurally which will now be described.

Chemical and structural differences between DNA and RNA:



Contains deoxyribose sugar

Contains ribose sugar

Contains the bases: Adenine, Thymine,

Cytosine and Guanine.

Contains the bases: Adenine, Guanine, Cytosine and Uracil. RNA does not contain Thymine.

Can only be hydrolysed by deoxyribonucleases (DNAses).

Can only be hydrolysed by ribonucleases (RNAses).

DNA is synthesized in 5'-3' direction.

RNA is synthesized in 3'-5' direction.

DNA is synthesized by DNA polymerase


RNA is synthesized by RNA polymerase Enzyme.

DNA is double stranded.

RNA is single stranded.

Similarities between DNA and Rna:

  • DNA and RNA have three main components: nucleotide, nitrogenous base and phosphoric acid.
  • DNA and RNA both have Adenine, Guanine and Cytosine nitrogenous bases.
  • Both DNA and RNA carry genetic information.
  • DNA and RNA are both polymers of nucleotides
  • Both DNA and RNA can be found in cell.

Function and roles of DNA:

Having discovered that DNA is the genetic material. It is valuable emphasizing that major role of DNA is storage and transmission of genetic information from parents to offspring or from one generation to another. DNA is able to undergo replication (synthesis of another copy of DNA) and being transcribed in RNA (transcription). These 2 procedures allow genetic information encoded in DNA found in nucleus to be transformed in functional biological material e.g. protein in cytoplasm.

Function and roles of RNA:

RNA, similar to DNA has shown to be general component of prokaryotic and eukaryotic cells. Though RNA molecules are not as stable as DNA, they also act as genetic information carrier in some organisms like some viruses where RNA is their genetic material.

Major functions of tRNA comprise:

Transportation of particular amino acids to ribosome's (site for protein synthesis) decoding genetic information in messenger RNA in terms of proper amino acid to be inserted in sequence of protein/polypeptide synthesised. Every tRNA carries one amino acid and has anticodon by which it recognizes message on mRNA template in protein synthesis.

Transfer RNAs contain 2 primary active sites, 3'hydroxyl terminus to which particular aminoacid are joined covalently and anticodon triplet. Ribosomal RNAs (rRNA) serve as structural framework for ribosomes. Hinging mechanism between two ribosomal subunits allow translocation and mRNA movement.

Messenger RNA (mRNA) is direct carriers of genetic information from nucleus to cytoplasmic ribosomes. Every eukaryotic mRNA have information for only one polypeptide and is thus monocistronic while prokaryotic mRNA can have information for more than one polypeptide chain and thus designated polycistronic.

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