Cell Protein Production

Transcription:process of mRNA formation.

1. Triggered by chem. messengers from cytoplasm which bind to DNA

2. This causes release of RNA polymerase (enzyme) which splits DNA apart (Generally 17 base pairs at a time) into a ‘template’ and ‘coding’ strand (RNA will mimic the coding strand)

3. There are ‘start’ and ‘stop’ triplets so the RNA polymerase knows where mRNA chain begins and ends.

Processing & Splicing- Once pre-mRNA has been formed (a direct copy of the coding strand) it must be modified before it can leave the nucleus- Not all triplets created from DNA are codons as some do not code for a specific amino acid.- These are described as ‘Introns’.- Introns: regions of mRNA which have no particular function and need to be removed- Exons: regions of mRNA which code for a specific amino acid. (codons)

Translation- This involves the actual production of the protein using info from mRNA.- A ribosome attaches itself to the mRNA and will being to piece together the amino acid chain based on the code from the mRNA.- The ribosome will being at the ‘start’ codon (AUG) and will end at the ‘stop’ codon (UAA, UAG or UGA)- Small segments of tRNA (transfer RNA) have a specific amino acid attached to them. These segments of tRNA are structured in such a way that they have a sharp ‘loop’ at one end which has a specific codon called the ‘anticodon’ which will correspond to a specific codon on the mRNA strand.

Translation-- The tRNA molecules line up and the amino acids attached will then form a bond with each other (requiring energy of one ATP conversion)

TranslationProtein StructureFour levels of complexity:1. Primary structure: sequence of amino acids (one protein may have 10 000 amino acids)2. Secondary structure: coiled/folded shaped due to bonds between diff parts of chain3. Tertiary structure: further bending/folding into globular/fibrous shape4. Quaternary structure: two or more amino acid chains interact