DNA codes for proteins but also ensures that the A-Z sequence is correct. What about the production of phospholipids, cholesterol,…? Is there an analogous system of coding as with the proteins. You do have the ‘biochemical pathway for fatty acid metabolism’, but how is this mechanism controlled so that the correct structure is created?
Answer
Hello Franky,
DNA only codes for proteins and RNA: it determines the sequence of amino acids (for proteins) and nucleotides (for RNA). The production of phospholipids, polysaccharides and all other biomolecules is achieved by the presence of the right enzymes to catalyze the synthetic reactions (and these are proteins that are encoded on the DNA). For the synthesis of all biomolecules (and also for all other reactions in living organisms) it can be said: if the enzymes are not available (this is not coded on the DNA of the organism or are not made in the cell at that time of the organism) then the reaction does not work (or better: much, much too slow, infinitely slow). In this way, the cell determines (by code on the DNA and the moment of its expression) which proteins (and therefore also which enzymes) it makes, and also which other biomolecules are synthesized. The biochemical pathway(s) are controlled by DNA-level regulation, called induction and repression (and these determine which genes and therefore which RNAs and proteins are expressed at that moment) and by protein-level regulation (activation and inhibition). : these determine how active the existing proteins are at that moment. The former is also referred to as coarse adjustment, the latter as fine adjustment. Of course you can only control what is coded (so what genes are available on the DNA).
Kind regards,
Myriam Mayers,
lecturer KULeuven@KHLim – Diepenbeek
Answered by
ir. Myriam Meyers
industrial microbiology and biochemistry
Old Market 13 3000 Leuven
https://www.kuleuven.be/
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