Energy
The ability to do work (to cause change)
Forms of energy
Potential
Kinetic
Thermodynamics
study of the interactions of heat and other forms of energy
First law of thermodynamics
energy cannot be created or destroyed but transformed from one form to another
second law of thermodynamics
energy systems experience an increase in the amount of disorder over time (i.e. entropy increases)
Delta G
The change in available (free) energy during an energy transformation
Positive Delta G
the energy available to do work goes up at the end of the transformation
Kinetic energy is used to increase potential energy
Endergonic
Negative Delta G
the energy available to do work goes down at the end of the transformation
potential energy is released as kinetic energy
exergonic
Mechanical work
ATP provide the energy requirement for motor proteins (usually cytoskeletal) to facilitate cellular or subcellular movement
Transport work
ATP provide the energy requirement for membrane protein to perform active and bulk transport
chemical work
ATP provides the energy requirement for enzymes to perform anabolic reactions like dehydration synthesis
Functions of ATP
Provides energy for cell functions
powers cellular work by coupling exergonic reactions to endergonic
Structure of ATP
3 Phosphate groups
Ribose
Adenine
Metabolism
The sum total of a cell's chemical reactions is referred to as it's metabolism.
Two reactions of Metabolism
anabolic and catabolic
Anabolic reactions
"building" reactions
Builds energy
endergonic
Controlled by enzymes
Catabolic reactions
"digestive" reactions
Exergonic
controlled by enzymes
active site of an enzyme
where the substrate binds on an enzyme
enzyme-substrate complex
when the substrate binds to the active site of the enzyme
general principles for enzymes
1. substrates need to diffuse into the active site
-heat is required as an energy source for all enzymes
2. the active site is specific to the substrate
Catabolic reactions thermodynamically
do not require ATP
catalyze "spontaneous" reactions w/ negative delta G
Lower the activation energy
activation energy
the energy needed doe a reaction to get started
anabolic reactions thermodynamically
require ATP to "drive" the reaction due to positive delta G
competitive inhibition
a competitive inhibitor interferes with active site of an enzyme so the substrate cannot bind
noncompetitve inhibition
a noncompetitive inhibitor binds to the allosteric site, changing the shape of the enzyme so it cannot bind to the substrate
activator
can bind to an allosteric site to promote enzyme action