Final answer:
When a single mRNA encodes three proteins, it is referred to as polycistronic mRNA. This type of mRNA allows for the production of multiple proteins from one mRNA molecule through a series of triplet codons, a principle that applies universally in genetic coding. Translation of this mRNA involves transfer RNA (tRNA) and can occur simultaneously by multiple ribosomes forming a polysome.
Step-by-step explanation:
When all the genes are transcribed as a single mRNA encoding the 3 proteins, this is called a polycistronic mRNA. In such cases, a single messenger RNA molecule is used to produce more than one protein product. This is commonly seen in prokaryotes where transcription and translation are coupled, and multiple proteins are synthesized from one mRNA transcript. The mRNA molecule carries a sequence of codons, each of which corresponds to an amino acid. In polycistronic mRNA, several such sequences are present, allowing for the synthesis of multiple proteins.
Each triplet codon on the mRNA corresponds to a specific amino acid during the process of translation. In prokaryotes, the genetic code is expressed directly from the DNA to proteins through the intermediate of mRNA. This is different in eukaryotes, where a single gene usually leads to a single mRNA molecule. However, the genetic code in both prokaryotes and eukaryotes operates through the triplet codon principle, which is universal across all organisms.
Translation factors, such as transfer RNA (tRNA), are critical in this process. tRNA molecules serve as the adapters that read the mRNA codon and bring the corresponding amino acid to the growing polypeptide chain during translation. Together, multiple ribosomes can form a polysome, translating the same mRNA transcript simultaneously, creating multiple copies of the protein.