Question

The genetic code is (almost) universal, meaning that ribosomes from bacteria, fish, mice or humans will translate a particular open reading frame into identical proteins. However, it is not possible to place a message from bacteria into a human cell (or vice versa) and expect to see a protein produced. Why?

Answer 1

Genetic code:

Genetic code is universal because all organisms descended from the common ancestor over evolution, genetic code is one shared aspect that is present common from bacteria to human.This common feature is used to produce the human protein in bacteria. But there are many differences in translation process in bacteria and human.

• Ribosome that carries out the protein synthesis in bacteria is different from human.
• The bacteria has less introns, where as human has more number of introns in-between the exons.
• Spicing is the process that is carried out by higher eukaryotic organisms to remove the non coding regions.
• Bacteria do not have introns and there is no process of splicing, when placing the human gene in bacteria for translation fully functional mRNA has to be placed.
• Bacteria is polycistronic, many ribosomes bind to single mRNA to produce many proteins.
• In Eukaryotes translation recognizes the 5’ cap of mRNA and initiation of protein synthesis begins from the start site of AUG.
• Eukaryotic mRNA is monocistronic produce only single protein.
• If the same gene is needed to produce different protein then it undergoes different form of splicing to produce monocistronic mRNA and a alternate form of protein.
• Thus bacterial gene cannot be translated in human cell. When bacterial infection occurs to human it produces bacterial proteins which cause disease to human.
• There are many antibiotics which are used to interrupt the protein synthesis of the bacteria and destroy them.
• If human mRNA had to be translated in bacterial cell, then introns are removed, fully functional form of mRNA is introduced into the bacteria to produce the protein and this process is called genetic engineering.