Messenger RNA (mRNA) is synthesized from a gene segment of DNA which ultimately contains the information on the primary sequence of amino acids in a protein to be synthesized. The genetic code as translated is for m-RNA not DNA. The messenger RNA carries the code into the cytoplasm where protein synthesis occurs.
Genetic Code:
Each gene (or distinct segment) on DNA contains instructions for making one specific protein with order of amino acids coded by the precise sequence of heterocyclic amines on the nucleotides. Since proteins have a variety of functions including those of enzymes mistakes in the primary sequence of amino acids in proteins may have lethal effects.
How can a polymeric nucleotide with only four different heterocyclic amines specify the sequence of 20 or more different amino acids? If each nucleotide coded for a single amino acid, then obviously only 4 of the 20 amino acids could be accommodated. If the nucleotides were used in groups of two, there are 16 different combinations possible which is still inadequate.
It has been determined that the genetic code is actually based upon triplets of nucleotides which provide 64 different codes using the 4 nucleotides. During the 1960's, a tremendous effort was devoted to proving that the code was read as triplets, and also to solving the genetic code. The genetic code was originally translated for the bacteria E. Coli, but its universality has since been established. The genetic code is "read" from a type of RNA called messenger RNA (mRNA). Each nucleotide triplet, called a codon, can be "read" and translated into an amino acid to be incorporated into a protein being synthesized. The genetic code is shown in Figure 7.
Several distinctive features of the genetic code are clearly evident. First, all of the 64 codons or triplets have a known function, with 61 coding for amino acids and the other 3 serving as a stop or termination signal for protein synthesis. Secondly, the code is degenerate, meaning that there are usually several codons for each amino acid. Only methionine and tryptophan have a single codon. More specifics on the importance of the degeneracy of the genetic code will be discussed in a later section.
The basic unit of messenger RNA is nucleotides. Nucleotides are also the basic units of DNA and are organic molecules.
Codon
There are three main types of RNA: messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA). There are other types, such as the transfer-messenger RNA in some bacteria.
The mRNA carries information to the ribosomes. This is known as 'messenger' RNA because it carries the message, the base sequence from the nucleus to the ribosome. This mRNA is then translated into an amino acid sequence (polypeptide/protein) at the ribosome.
Messenger RNA carries a copy of DNA out of the nucleus and into cytoplasm. Transfer RNA then carries amino acids to the copy of DNA to form a protein chain.
There are three primary types of RNA involved in protein synthesis: messenger RNA, transfer RNA and ribosomal RNA. Whereas most types of RNA are the final products of their genes, messenger RNA (mRNA) is an intermediate in the information transfer process
Amino acids are the basic units of messenger RNA. mRNA is synthesized from DNA and is a single stranded molecule.
DNA and RNA
Codon
DNA code is copied to messenger RNA, abbreviated mRNA.
DNA and RNA
RNA
messenger Rna.
messenger RNA
There are three main types of RNA: messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA). There are other types, such as the transfer-messenger RNA in some bacteria.
RNA is a nucleic acid,messenger RNA is a form of RNA that carries the instructions for making a protein form a gene and delivers it to the site of translation
This is called messenger RNA. mRNA
The mRNA carries information to the ribosomes. This is known as 'messenger' RNA because it carries the message, the base sequence from the nucleus to the ribosome. This mRNA is then translated into an amino acid sequence (polypeptide/protein) at the ribosome.