Protein Synthesis

Protein synthesis occurs because DNA is a very large molecule and therefore cannot leave the nucleus to pass the coding to ribosomes which can make the protein required. So, mRNA is used to copy the coding and since it is smaller, it can exit the nucleus. 

The first part of protein synthesis is transcription, in which the coding on the DNA strands are copied into an mRNA molecule. First, RNA polymerase attaches to the DNA and separates the 2 strands so that one can be used as a template. It begins at the start of a gene and adds complementary RNA nucleotides with the bases Adenine, Uracil (which subsitutes Thymine), Cytosine and Guanine. Once a stop codon is reached, the mRNA is released and is called pre-mature mRNA. Splicing then occurs: the noncoding introns are removed and the remaining exons are joined together. It is now called mature mRNA. The mature mRNA leaves the nucleus through a pore. Outside…