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Transcription:process of mRNA formation.1. Triggered by chem. messengers from cytoplasm which bind to DNA2. 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)
Translation Protein Structure Four 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 chain 3. Tertiary structure: further bending/folding into globular/fibrous shape 4. Quaternary structure: two or more amino acid chains interact
