Wang JiayuANTH 10101/30/2018Discussion 3First of all, Protein synthesis is the process by which organisms synthesize proteins according to the genetic information on messenger ribonucleic acid (mRNA) that is transcribed from DNA. Protein synthesis is a two-step process which involves transcription and translation. Transcription is the production of messenger RNA (mRNA) templates containing protein sequences from the genome for translation.
Only one strand of the DNA double helix is required to be transcribed. Ribonucleic acid polymerase (RNA polymerase) first binds to a particular region of DNA that serves as the start of transcription and this binding region is called the promoter. When RNA polymerase binds to the promoter, the DNA strand begins to unroll. The second transcription step is transcriptional extension. RNA polymerase, together with the uncoded template strand, synthesizes ribonucleotide polymers. The reason why RNA polymerase does not use encoded chains as a template is that any copy of the strand produces a complementary set of underlying sequences. Only the uncoded strand will serve as a template for copying the encoded strand. When the polymerase reaches the final stage, the newly transcribed messenger RNA (mRNA) needs to be modified to reach other parts of the cell, including the cytoplasm and the endoplasmic reticulum.
In eukaryotes, the most important steps of gene splicing occur at this stage.Then it comes to the process of translation. In the process of translation, mRNA previously transcribed from DNA is decoded by special cellular structures to make proteins. This particular cellular structure is called ribosome.
Ribosomes can provide a place for another special type of RNA, called transport RNA (tRNA), to bind to mRNA. Within the tRNA there is a set of “anticodons” that can form the hydrogen bond with the corresponding mRNA in the ribosome. Therefore, the corresponding tRNA (chemically bound to a specific amino acid) will be directed to the ribosome, adding to the developing polypeptide. Ribosomes run one after another on the mRNA codon, and the other tRNA attaches to the ribosome. The first tRNA is released, but the amino acid attached to the tRNA is transported to the second tRNA and binds to its amino acid. This shift continues until one long chain of amino acids is created. When the entire unit reaches the final codon of mRNA, it will leave and the newly formed protein will be released, which is the completion stage.
In this step, a lot of enzymes will be used to assist the whole process.