How we obtain
energy!
ATP & ADP
WHAT IS ATP?
¡  Adenosine triphosphate (ATP)
¡  Supplies energy to ALL cells
¡  One molecule of ATP is composed of 3 parts:
1.  Nitrogenous base (Adenosine)
2.  Sugar (Ribose)
3.  Three phosphate groups
§  These three groups are bonded together by HIGH ENERGY BONDS
BREAKING BONDS IN ATP
¡  Cells break the bonds between the 3 phosphates to supply
energy for most cellular functions
¡  When the bond breaks holding the phosphate, ATP is turned
into ADP
§  With a phosphate available for reuse
USE AND RELEASE OF ENERGY
¡  When any of the phosphate bonds are broken or formed,
energy is involved
§  Energy is released when a phosphate is removed from ATP
§  Energy is used when phosphate is attached to the molecule
¡  To constantly supply the cell with energy, the ADP is recycled
creating more ATP, which carries much more energy than ADP
ATP – ADP CYCLE
¡  To supply cells with energy, a “high energy” bond in ATP is
broken.
§  ADP is formed and a phosphate is released back into the cytoplasm
§  ATP à ADP + phosphate + energy
¡  ADP becomes ATP when a free phosphate attaches to the ADP
molecule
§  The energy required to attach the phosphate to ADP is much less
than the energy produced when the phosphate bond is broken.
§  ADP + phosphate + energy à ATP
ANIMATIONS
¡  ATP/ADP Cycle Animation
THE ENERGY STORAGE PROCESS
1.
The ADP molecule is waiting for
a “food molecule”
§
Lipid, carbohydrate, or protein
2.
When the food molecule is
broken down an extra
phosphate attaches to the ADP
to form ATP, which can then be
used as energy in the cell.
3.
When ATP is broken down and
stripped, the energy is then
transferred to be used for the
creation of macromolecules
(large molecules) like proteins.
¡  Ever y time you eat food, or take
in energy, you are essentially “recharging” your ADP by adding
extra Phosphates in order to form
ATP
FOOD / FUEL MOLECULES
¡  Carbohydrates:
§  Molecules most commonly broken down to produce ATP
§  Remember “immediate energy”???
§  From one glucose molecule you can form up to 36 ATP!
¡  Lipids:
§  Store the MOST energy
§  These are fats!
§  80% of energy in the body is from lipids
§  From one triglyceride molecule you can form up to 146 ATP!
¡  Proteins:
§  Least likely molecule to be broken down to make ATP
§  Amino acids are not usually needed for energy
§  If used, they produce the same amount of energy as a carbohydrate.