29 - Wednesday November 3 2010 Lecture 29 Announcements...

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Wednesday, November 3, 2010 Lecture 29 Announcements: Want your midterm exam regraded? Submit for regrading by Friday 11/5 (the usual 1-week span after return of the exam) Info session about the HCEC process next spring: Friday 11/5 at 2:55PM in Comstock B108: How to write the personal statement (what are they looking for?); how to get the best set of 3 recommendation letters. Let’s meet and set the date for the make-up final exam: check your calendars for conflicts! Then we will meet briefly right after the lecture on Wed 11/10 to choose the day and time for the make-up exam. Monday's lecture: control of glycogen phosphorylase: hormonal and local control R - T equilibrium of GP Control of PFK-1: allosteric how a small change in [ATP] results in a large change in [AMP] hormonal vs local control: why different tissues respond differently control of pyruvate kinase: also hormonal and local control, also different tissues respond differently Today's lecture: p. 205 Now the cell has made pyruvate. What happens next? That depends on exactly how rapidly the organism needs energy! What if we need ATP rapidly? The rxns of glycolysis can supply ATP quickly. But if glycolysis simply runs repeatedly, cellular concentration of NAD + (which is required for the oxidation/reduction step of glycolysis) gets too low. When cells run out of NAD + , glycolysis shuts down! But let's consider all the possibilities more systematically. Here is a chart to describe the "ATP-producing systems": System Time to Deplete to Zero at Maximum Power Use phosphocreatine ATP 10-20 sec glycogen lactate 4 min glycogen CO 2 + H 2 O 1-2 hr fatty acid CO 2 + H 2 O days In muscle, the following occurs:
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phosphocreatine + ADP + H+ ATP + creatine In muscle, phosphocreatine, which is a "high-energy molecule", is utilized for the most rapid ATP production. But this works only until the phosphocreatine is used up, which is about 10 to 20 seconds when maximum power is expended. This is the body's fastest supply of ATP, used when maximum power is needed, e.g. in competitive running of distances shorter than 200m. Note that in muscle, [ATP] ~
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29 - Wednesday November 3 2010 Lecture 29 Announcements...

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