Question

-Identify the three sites of regulation of glycolysis (including enzymes and nature of inhibitors) ?



-Concepts of end-product inhibition & lack of coenzymes/substrates explained ?



-Identify the role of changing concentrations of ATP, ADP, hydrogen ions and other intermediates such as citrate in regulation of glycolysis ?



-Discuss the role that a lack of oxygen plays in causing the cell to switch from anaerobic to aerobic respiration (including the need to recycle NAD) ?



-Explain the key role of both forms of fermentation in recycling NAD ?



-Include the effect of the build-up of of lactic acid (and its removal) during anaerobic glycolysis in muscle cells.

please help

Answer 1

Some of the questions have some quite long answers as they are not very specific so I start with the first one:
1. Phosphofrutokinase: In the liver,phosphofrutokinase is inhibited by citrate, an early intermediate in the citrate acid cycle. A high level of citrate in the cytoplasm means that biosynthetic precursors are abundant, and so there is no need to degrade additional glucose for this purpose. Citrate inhibits phosphofrutokinase by enhancing the inhibitory effect of ATP.

2. Hexokinase: Is regulated glucose 6-phosphate as another specialized isozyme of hexokinase called glucokinase, which is not inhibited by glucose 6-phosphate. Glucokinase phosphorylates glucose to another isomer that can not be used in the glycolysis. This is done by that glucokinase have a affinity for glucose 50 times lower than hexokinase and therefor is only real active when glucose is found in small amounts.

3. Pyruvate kinase. This enzyme is inhibited by a phosphorylation of the enzyme it self, that then become less active. So when ATP is formed in great levels it can be degraded to ADP and inorganic phosphate, where the inorganic phosphate is bound to the enzyme that then become less active. keywords: phosphorylated pyruvate kinase (less active), dephosphylated pyruvate kinase (more active)

Answer 2

thanks a lot for at least starting with thr first one :)

Answer 3

could you please help me with the others too?