Lec17 - MCB 102 Professor Markus Pauly 02/28/11 Lecture 17...

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MCB 102 Professor Markus Pauly 02/28/11 Lecture 17 ASUC Lecture Notes Online is the only authorized note-taking service at UC Berkeley. Do not share, copy, or illegally distribute (electronically or otherwise) these notes. Our student-run program depends on your individual subscription for its continued existence. These notes are copyrighted by the University of California and are for your personal use only. D O N O T C O P Y Sharing or copying these notes is illegal and could end note taking for this course. ANNOUNCEMENTS The second part of the lecture reader is now available on bSpace. Please print it out and bring it to lecture. LECTURE Enzyme regulation is needed to maintain constant levels of metabolites such as ATP and NADH in different cells. So far we have explored the network of metabolism starting with glycolysis, branching to two types of fermentations, then gluconeogenesis, and pentose phosphate pathway. Things are linked within the cell, and thousands of reactions occur at the same time. We therefore need regulation. Cells are not really in a steady state since reactants and products are constantly removed. It is essentially dynamic with a constant flux of energy. When there are changes to this flux, cells must compensate through metabolic regulation (maintaining homeostasis) and metabolic control (changing metabolic pathway). Factors that determine enzyme activity include control of enzyme abundance and control of existing enzyme. Controlling the activity of existing enzyme can be done through allosteric regulation, association with regulatory protein, sequestration (compartmentation), covalent modification (phosphorylation), and most importantly, substrate regulation. Cells maintain energy supply through the ratio of ATP/AMP. ATP indicates high energy and AMP indicates low energy in the cell. When the level of ATP starts depleting, AMP-activated kinase signals to other tissues in the body to stop synthesis and increase glucose breakdown. If the forward enzyme (glycolysis) and reverse
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Lec17 - MCB 102 Professor Markus Pauly 02/28/11 Lecture 17...

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