RNA

RNA
Definition
The single stranded helical polynucleotide contain ribose sugar and uracil instead of thymine is called RNA.
Location
RNA is found in the nucleus (in nucleolus 10%) as well as in the cytoplasm (90%).
Types of RNA
There are three types of RNA.
1. Ribosomal RNA (rRNA)
2. Transfer RNA (tRNA)
3. Messenger RNA (mRNA)
1. Ribosomal RNA (rRNA)
The class of RNA found in ribosomes is called ribosomal RNA.
Function
During polypeptide synthesis it provides the site on the ribosome where the polypeptide is assembled.
2. Transfer RNA (tRNA)
A second class of RNA is called transfer RNA is much smaller. Human cell contains more than 40 different kinds of tRNA molecules.
Function
During polypeptide synthesis tRNA molecules transport the amino acid into the ribosome for the synthesis of polypeptide chain.
3. Messenger RNA (mRNA)
It is long strand of RNA that passes from the nucleus to the Cytoplasm.
Function
During polypeptide synthesis, mRNA molecules brings information from the chromosomes to the ribosomes to direct the assembly of amino acids into a polypeptide.