The RNA World Dossier

Types, Enzymes & Cellular Secrets

The Division of Labour

In Eukaryotes, the task of transcription is split among three specialized RNA Polymerase enzymes. Below is the classified data on their production, structure, and unique functions.

rRNA

80%
Full Name
Ribosomal RNA
Primary Function
The structural and catalytic engine of the ribosome. It forms peptide bonds (Ribozyme activity).
Types (Svedberg Unit)
Prokaryotes (70S): 23S, 16S, 5S
Eukaryotes (80S): 28S, 18S, 5.8S, 5S
PRODUCED BY RNA POLYMERASE I
(Except 5S rRNA)

tRNA

15%
Full Name
Transfer RNA (Soluble RNA / sRNA)
Why "Soluble"?
Called sRNA because it is soluble in 1M NaCl solution. It is the smallest RNA.
The Numbers
Size: 73-93 Nucleotides.
Shape: Clover-leaf (2D) / Inverted L-shape (3D).
PRODUCED BY RNA POLYMERASE III
(+ 5S rRNA & snRNAs)

mRNA

2-5%
Full Name
Messenger RNA
Primary Function
Carries the genetic blueprint (codons) from DNA to the ribosome. It is the most unstable RNA.
Record Breaker
Largest Gene (Human): Dystrophin (2.4 million bases).
Structure: Linear, has Cap (5') & Poly-A Tail (3').
PRODUCED BY RNA POLYMERASE II
(Transcribes hnRNA precursor)

Classified Data Summary

RNA TYPE ENZYME (EUKARYOTES) KEY FUNCTION CELLULAR %
rRNA RNA Polymerase I Catalytic Core (Ribozyme) 80%
tRNA RNA Polymerase III Amino Acid Adapter 15%
mRNA RNA Polymerase II Genetic Messenger 2-5%
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