Protein synthesis

• Proteome is the complete set of proteins expressed by an organism
• Proteome can describe proteins expressed at a particular time in a particular cell
• Proteome of a cell or organism is active and transient
• Proetome is constantly changing in response to its environment
• Genome is constant whereas proteome is transient
• Genome contains polynucleotides and proteone contains polypeptides
• Transcription involves DNA helicase separating the DNA at the start code, RNA polymerase moves along the DNA template adding free RNA nucelotides to the 3 prime end this produces a pre-mRNA molecule
• Splicing refers to the removal of introns from the pre-mrNA strand, this creates a mature mRNA strand
• Exons are DNA sequences that code for polypeptides
• Introns do not code for proteins and hence need to be removed
• Translation involves the mRNA is drawn to the ribosome and binds to the small ribosomal unit, the large ribosomal unit and the first tRNA binds, mRNA then moves along the ribosone binding two complementary tRNAs at a time, they continued to bind until a stop codon is reached and amino acid sequence is released
• tRNA delivers amino acids connected by peptide bond, these bonds are catalysed by the large ribosome using ATP