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Anaerobic and Aerobic Glycolysis

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Anaerobic and Aerobic Glycolysis Powered By Docstoc
					Anaerobic and Aerobic
     Glycolysis
Topics that will be covered…
~Overview of Glycolysis
and description of the
pathway
~Divergence to
anaerobic metabolism
within the muscle and
how does aerobic
metabolism also help
energize our muscles?
~The three main energy
sources for our muscles.
                      Glycolysis
~Ancient metabolic pathway used by the earliest bacteria
~This pathway existed about 1 million years before oxygen
existed on the earths surface.
~Basically, glycolysis is a set of chemical reactions that
produce energy (in the form of ATP) from the sugar glucose.
~In the 10 steps of glycolysis glucose is converted to pyruvate
and the reaction yeilds 2 pyruvate molecules and 2 net ATP
molecules per glucose.
The glycolysis pathway
     Now what can be done with
           pyruvate?
Anaerobic glycolysis is the process by which the normal pathway
of glycolysis is routed to produce lactate. It occurs at times when
energy is required in the absence of oxygen. It is vital for tissues
with high energy requirements, insufficient oxygen supply or
absence of oxidative enzymes.

 Glycolysis produces reduced forms of NAD in the energy generation
  phase.
 In an anaerobic environment, lactate dehydrogenase converts pyruvate
  to L-lactate and restores NADH to NAD+ which can then be used in
  once again in the glycolysis pathway.
                 The fate of pyruvate

  Pyruvate + NAD+ + CoA          Acetyl CoA + CO2 + NADH + H+


Using pyruvate in this way (to keep glycolysis running at a paltry
2ATP per glucose) may seem wasteful considering the much larger
amount of ATP generated should it enter the citric acid cycle (as
acetyl CoA). However, glycolysis can run at a very high rate and
thus meet the ATP demands of the cell (at least for a short time) even
though it is a very expensive use of glucose.

But… a continuous buildup of lactic acid could lead to acidosis
So then what do our muscles do
  with the lactate produced?
       It turns out breakdown of glucose to pyruvate within muscle

              cells is not the primary source of ATP synthesis.

ATP is the immediate source of energy for muscle
contraction. Although a muscle fiber contains
only enough ATP to power a few twitches, its
ATP "pool" is replenished as needed. There are
three sources of high-energy phosphate to keep
the ATP pool filled.
     •creatine phosphate
     •glycogen
     •cellular respiration in the mitochondria of
     the fibers.
     Creatine phosphate and cellular respiration as a
              source of ATP for the muscle
The phosphate group in creatine phosphate is attached by a "high-
                energy" bond like that in ATP.
         Creatine phosphate + ADP ↔ creatine + ATP

                                          Aerobic production
                                          of ATP aids in the
                                           reproduction of
                                          glycogen from the
                                          lactic acid that has
                                          built up within the
                                           muscle.
                           References…
Biochemistry second edition written by Christopher Mathews and
K.E. Van Holde.

Pictures from:

•http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Muscles.html

•http://www.umanitoba.ca/faculties/medicine/units/biochem/coursenotes/blanchaer_
tutorials/Bob/metabolism

•http://www.arabidopsis.org:1555/ARA/new-image?type=PATHWAY&object=
•ANAGLYCOLYSIS-PWY

				
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posted:8/26/2012
language:English
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