How is the nucleotide seguence in the mRNA translated into a polypeptide sequence?

Answer 1

As we all know, mRNA undergoes translation to form a polypeptide sequence.

Besides the mRNA, there are still the tRNA ( transfer RNA ) and rRNA ( ribosomal RNA ). All these three types of RNA are essential in determining the polypeptide sequence.

This is the because, mRNA only acts as a messenger. A messenger to bring the information from the DNA to the ribosome to synthesis protein.

the tRNA transports the required amino acid to form the polypeptide refering to the mRNA while the rRNA builds a site for the polypeptide synthesis to occur.

For translation to occur, the essential components are required : tRNA with it's anticodons to the start codon - UAC - ( start codon = AUG- methionine). the subunits of the ribosomal RNA and the mRNA that needs to be translated.

i)the tRNA with the correct anticodons binds to the start codon.

ii) the next tRNA recognizing the next codon locates itself on the ribosome and the first tRNA is transferred by ribosome.

iii) Once the amino acid are in place, peptide bonds are formed between them and a polypeptide chain is formed. the first tRNA leaves the ribosome while the next tRNA takes it's place. As another tRNA recognizes the next codon, it locates itself on the ribosome once more.

iv) Translation goes on until the ribosome reaches either one of the stop codon. -- UAA / UAG/ UGA.. found on the mRNA.

v) When the ribosome arrives at the stop codon, translation stops. The ribosome splits to it's two sub units, and the newly synthesized polypeptide chain is released from the mRNA.

vi) the tRNA and rRNA can be reused to form new polypeptides on other mRNA strands.