ch369_3-4_11mar2011_notes

ch369_3-4_11mar2011_notes - In glycolysis step #5, triose...

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Unformatted text preview: In glycolysis step #5, triose phosphate isomerase catalyzes the interconversion of two 3-carbon sugars. At typical cellular conditions, the free energy change for the forward (left-to-right) reaction is about 2 kJ/mol. At equilibrium, the concentrations of dihydroxyacetone phosphate & glyceraldehyde-3-phosphate are: A) Equal. B) Both trioses are present at equilibrium, but there is more glyceraldehyde-3-phosphate. C) Both trioses are present at equilibrium, but there is more dihydroxyacetone phosphate. What is glycolysis? What is the overall point of glycolysis? Why make ATP? What’s it good for? What are NAD + and NADH, and why do we need these? Which glycolysis reactions are irreversible? What is gluconeogenesis? Why is it useful? Why must these pathways be regulated? Which steps are regulated? Why is it sometimes useful to convert pyruvate to lactate (or ethanol) ? The reverse of glycolysis is called “ gluconeogenesis ”. In humans, liver cells can do gluconeogenesis . (liver cells have the enzymes that can do the reverse of glycolysis steps 10, 3 and 1) Reversing step 10 of glycolysis requires 2 enzymes for a 2-step reaction, consuming ATP and GTP: Pyruvate carboxylase requires a biotin prosthetic group, attached to a lysine on the enzyme. Gluconeogenesis. Biotin is a prosthetic group for pyruvate carboxylase, an enzyme in gluconeogenesis. Biotin prosthetic group on lysine Vitamin B7 - Biotin. Used by pyruvate carboxylase in gluconeogenesis. Also used in fatty acid synthesis, and other functions. Vitamin B7 - Biotin Gluconeogenesis is energetically expensive . It is regulated, so only used when needed. Regulatory points are the same as glycolysis (the reverse of steps 10, 3, 1). fructose bisphosphatase regulated regulated regulated What to do with extra glucose when it isn ’t needed ?...
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This note was uploaded on 04/02/2011 for the course CH 369 taught by Professor Kbrowning during the Spring '07 term at University of Texas.

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ch369_3-4_11mar2011_notes - In glycolysis step #5, triose...

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