Protein Synthesis

The first step in protein synthesis of a polypeptide strand is to change the DNA into mRNA. This is called transcription, RNA Polymerase creates mRNA because DNA has a double helix and is too big to fit through a pore in the nuclear membrane. Protein synthesis can only occur in Eukaryotic cells, cells that have a nucleus. The second step is RNA processing where the introns get cut out by spliceosomes and the exons stay the same. This happens in the cytoplasm, a guanine cap (3 phosphates) and poly A tails (bunch of  A nucleotides) are placed to protect the message. After RNA processing, the mRNA goes to the APE site. The "A" stands for accepting site, where the mRNA is accepted. The "P" stands for peptide site, where peptide bonds are formed. The "E" site stands for exiting site where the mRNA codon (3 pairs of RNA base)/ peptide bonds are matched with anticodons (tRNA) and leave the ribosome which reads from 5 carbon end to 3 carbon end, whereas in transcription it reads from 3 carbon end to 5 carbon end. The tRNA also buses amino acids. The last step is translation, when the mRNA is translated into proteins.