gluconeoglycogen-long

gluconeoglycogen-long - GLUCONEOGENESIS...

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--  GLUCONEOGENESIS GLUCONEOGENESIS   --   Definition Definition : the  biosynthesis  of glucose   primarily from pyruvate and its precursors.  
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The gluconeogenesis pathway is similar to the reverse  of glycolysis but  differs   at critical sites.   control of these opposing pathways  is  reciprocal  so that physiological conditions favoring one disfavor the other and vice versa.    General principles of metabolic control --  a)  pathways are not simple reversals of each other  and b)  under reciprocal control
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  Why do we produce glucose? Why do we produce glucose? a)  Need to maintain glucose levels within a  narrow range in blood. b)  Some tissue-- brain, erythrocytes, and muscles in exertion use glucose at a rapid rate and sometimes require  glucose in addition to dietary glucose. c)  The brain uses mostly glucose and  erythrocytes can use  only  glucose as a source  of energy.
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Where is glucose synthesized? Where is glucose synthesized?   The liver comes to rescue. The  liver  is the  major location for gluconeogenesis.   The major precursor for glucose  biosynthesis is pyruvate.
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What are the sources of pyruvate What are the sources of pyruvate precursor? precursor?   lactate –from muscle, forms pyruvate  some  amino acid   carbon skeletons- from  diet or breakdown of muscle protein during  starvation- most important is  alanine   TCA cycle intermediates   propionate   from breakdown of certsin fatty  acids and amino acids.   glycerol   from certain lipids.
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  Lactate   is the primary source for pyruvate. -- In muscle, lactate is produced in great quantities during exertion. -- This excess lactate cannot be further oxidized in muscle. -- Lactate is released from the muscles to the blood and travels to the  liver  for conversion to pyruvate and, ultimately to glucose.   Notice glucose cannot be made from acetyl CoA 
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Gluconeogenesis Gluconeogenesis - beginning - beginning
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            fructose 1,6- bis phosphate                         aldolase                   triose phosphate isomerase dihydroxyacetone              glyceraldehyde   phosphate                         3-phosphate
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                                 GLUCOSE GLUCOSE                      glucose                  P i BYPASS 3  6-phosphatase        ( hexokinase)                       Glucose 6-phosphate    phosphogluco-   isomerase                       Fructose 6-phosphate     BYPASS 2     fructose              P i      ( phospho-    1,6 bisphosphatase                  fructokinase)         Fructose 1,6- bis phosphate
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gluconeoglycogen-long - GLUCONEOGENESIS...

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