PPT Slide

Source of Energy for Critical Biological Systems

• Although the primary source of energy used in chemical rxns is ATP, other high energy phosphates do exist e.g. GTP, CTP

• Present in muscle cell at about 4-6 mM of ATP/kg muscle

• This is a very low concentration, but the turnover rate is very high (mol x s-1) -At rest + 40 Kg/24 hr (88 lbs) -Heavy Exercise = .5 Kg/min (1.1 lbs)

• This fact indicates that ATP is not a storage form for energy. Rather, it is a transmitter or carrier of energy.

• The concentrations of ATP, ADP, and AMP vary only slightly in normal cells under steady state conditions. This is an extremely critical aspect of cell life, and cells have very elaborate processes to ensure that this remains true under most, if not all conditions.

• Nevertheless, a sudden increase in demand slightly decrease ADP and slightly increases ADP, resulting in the acceleration of metabolism (more later). A new ìsteady stateî is formed.

Relevant Terms:

Steady State: A condition where energy created in the form of ATP equals breakdown.

Energy Charge: An indication of the availability of energy in a cell, characterized by the mathematical relationship of the concentrations of ATP, ADP, and AMP.

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