Question

-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) ?

please help.....

Answer 1

1. Feedback inhibition occurs when a series of reactions makes a lot of its specific product and the concentration of the products increase around the enzymes, and the product it makes is its own regulator substrate, it attaches to the regulator site on the first enzyme in the series (telling the series that it has enough, because there were enough to float around and bind to the active site), and stops further synthesis.
Think of cofactors as a puzzle piece that is needed in the active site for the substrate to fit properly. In the absence of cofactors, the substrate cannot attach, and the reaction cannot take place. Without substrates, the enzyme will not function, it remains inactive.

2. ATP is the entire reason for glycolysis, as it is the energy needed to drive most metabolic functions. When ATP concentrations are low, the cell sends glucose to be processed to harvest ATP. ADP is 'used up' ATP, so when there are high concentrations, they need to be phosphorylated (add phosphate group to make it ATP) to be used again as ATP. Hydrogen has the electrons (it is composed of one proton and one electron) needed for the electron transport chain, which makes tons of ATP (32-38) for each glucose molecule. Changing the concentrations of these will either drive the cycle or inhibit it, depending on what it needs.

3. Oxygen is the final electron acceptor for the electron transport chain during aerobic respiration because it is very electronegative (accepts electrons easily). During anaerobic respiration, it uses less oxidative (less willing to accept electrons) molecules like nitrate and sulfate. Anaerobic respiration is less efficient because the electrons are not accepted as efficiently as in the presence of oxygen. Because there are less electron acceptors that will quickly take electrons, electrons build up in the ETC because they have nowhere to go, and the NADH has nowhere to give its electrons. The result is that there is less NAD+ going back to the Krebs cycle to shuttle more electrons through.

Hope this helps.

Answer 2

thanx a lot :D