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
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).
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′).
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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