NE224 Lecture Notes - Lecture 10: Lac Operon, Pyrimidine Metabolism, Cytidine
9 Oct 2014
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Document Summary
Many different reactions occur in living systems and are intricately inter-related: e. g. metabolic pathways. Figure 16-1 map of the major metabolic pathways in a typical cell. The state of the system can be controlled by controlling enzyme activity: (i) control the amount of enzyme. If a pathway is not needed the enzymes are not made (see the example of the lac operon section 5. 4). (ii) control the activity of the enzymes present by binding effector molecules or covalent modification. Enzyme regulation topics: allosteric enzymes: modify activity by binding other molecules, which can enhance or inhibit activity phosphorylation: covalent modification zymogens: convert protein from inactive to active form tight binding proteins: protein-protein interactions to regulate enzyme activity. Catalyzes initial step in synthesis of pyrimidines, monomers that make up dna and rna: cytidine, thymidine and uridine, ch5. 1. Figure 13-6 schematic representation of the pyrimidine biosynthesis pathway. 6 catalytic subunits and 6 regulatory subunits (2 x c3) + (3 x r2)
