m-RNA or massenger RNA .

Explanation

(1)m-RNA is a simple molecule which shows linear structure without any folds.(2)It performs the function of transcription during protein synthesis.(3)m-RNA is formed from DNA by the process of transcription in the nucleus.Later it comes in the cytoplasm and moves to the ribosomes.Since it carries the messange for the protein synthesis from DNA to ribosomes.therefore,it is called messenger RNA(4)Of the total cellular RNA,m-RNA forms 3-5%.It has molecule wieght of about 5,00,000.(5)There are two ends in m-RNA molecule.viz.'3 and 5' ends.(6)The nucleotide of m-RNA are arranged in group of three triplets or codons.the sequence of codon on the m-RNA strand is called genetic code or m-RNA language or crytogram.(7)The beginning of m-RNA molecule is called start codon or initiation codon.It lies at 5' end.It is AUG or Sometimes GUG.(8)m-RNA ends at 3' end with stop codon or termination codon,where are UAA.UAG or UGA.(9)EACH codon on m-RNA specifies a particular amino acid.(E.g.AUG specifies glycine or g-glycine).(10)The codons UAA.UAG and UGA do not specify any amino acid and hence they are known as nonsense codons.(11)The main function of m-RNA is to carry coded informartion about the sequence of amino acids in the polypeptide chain,from DNA to ribosomes.This further leads to protein synthesis.