Biology Units 3/4
What is protein synthesis?
What is transcription?
Transcription is the first part of the process of protein synthesis. It takes place in the cell nucleus, where deoxyribonucleic acid (DNA) is housed in the chromosomes. As we all know, DNA is a double helix structure. From the two parallel strands, one acts as a template to produce messenger RNA. As an initiation step of transcription, RNA polymerase binds its self to a particular site in one of the DNA strands that will act as a template.
Following its attachment to DNA template strand, the polymerase enzyme synthesize a messenger RNA polymer under the direction of the template DNA. The messenger RNA strand continues to elongate until the polymerase reaches a 'terminator region' in the DNA template. Thus, DNA transcription encompasses three steps. Initiation, elongation, and termination. The newly transcribed messenger RNA is released by the polymerase enzyme which is then migrated to the cytoplasm to complete protein synthesis.
What is translation?
The second primary part of the process is translation. Contrary to transcription that occurs in the nucleus, translation takes place in the cytoplasm of the cell. This part is initiated as soon as the transcribed messenger RNA enters the cytoplasm. The ribosomes present in the cytoplasm immediately attach to the messenger RNA at a specific site, called the start codon. An amino acyl transfer RNA also binds at the messenger RNA strand. This phase is called initiation. As the ribosome moves along the messenger RNA strand, the amino acyl transfer RNA brings amino acid one by one. This particular stage is called elongation. At the termination phase, the ribosome reads the last codon of the messenger RNA strand. With this, end of the translation part and the polypeptide chain is released. Precisely speaking, in translation, the ribosomes and transfer RNA attach to the messenger RNA, which read the coded information present in the strand. Accordantly protein synthesis of a specific amino acid sequence takes place.