Energy

Flows in one direction

stored energy  Car at top of hill

energy in motion  Car rolling downhill

•  First Law     
• Total amount of energy in the universe is constant.  Energy can change form and be transferred.      

• Second Law      
• Energy changes from a more useful to a less useful form.  It becomes increasingly more random. 

A chemical reaction where energy is released as a byproduct of the reaction.

AB ---------} A + B + energy

Exergonic reactions release energy!

Chemical reactions that require an input of energy to make the reaction go.                                  

A  +  B + energy -------------} AB     

Endergonic reactions need energy!

• The energy released from an exergonic reaction is used to run an endergonic reaction.
• Exergonic reaction     
• ATP --------} ADP + P + energy

• Endergonic reaction   
• ADP + P + energy--------} ATP

• A series of chemical reactions making up a pathway.
• The pathway may be linear, cyclic or a combination.

• - Most metabolic reactions have a small energy difference-
• - This means that most are reversible.     
• - Direction of reaction depends on concentrations of reactants and products.  

Reactants are located on the flat end of the arrow and products on the pointy end!!