CBSE Class 12-science Answered

Features

Messenger RNA (mRNA)

Transfer RNA (tRNA)

Ribosomal RNA (rRNA)

Composition of RNA in the cell

About 5%

About 15%

About 80%

Length of the molecule

Longest

Shortest

Variable

Shape of the molecule

Linear

Clover leaf-like

Greatly coiled

Types

Numerous

About 60

Six

Role

Carry information from DNA

Carry amino acids to mRNA codons

Constitute major part of ribosomes

Shelf life

Very short, 2 mins-4 hrs, get degraded after translation

Long, can be used again and again during translation

Long, can be used again and again during translation

Ends of the molecule

Has initiation codon and leader sequence at 5’ end and termination codon and tailer sequence at 3’ end

5’ end has guanosine monophosphate and 3 end has CCA sequence of nitrogenous bases

Not definite

Functions

Receives genetic information from DNA through transcription, comes out of the nucleus into the cytoplasm and translates the coded information into a protein with a determined sequence of amino acids.

Picks up amino acid from the cytoplasm of the cell and brings it to mRNA template at a specific position for polymerisation.

Forms structural component of ribosomes and provides surface for the attachment of mRNA and tRNA and acts as ribozyme to catalyse the formation of peptide bond.