WHAT IS ENERGY?
•  Energy is the capacity to do work.
ENERGY FORMS
•  Thermal – can move molecules
•  Chemical – can change molecular
structure
•  Electrical – can move charged particles
•  Photo – can boost electrons
to higher orbits
ENERGY STATES
•  Potential
•  Kinetic
A FACT
•  About 1% of light energy that arrives
at our planet gets used in life processes
1’ST LAW OF
THERMODYNAMICS
•  Energy can be transformed from one
form to another BUT it can neither be
created nor destroyed
ORGANISMS CANNOT
CREATE ENERGY
•  THUS:
– Form and function often
reflects constraint
ORGANISMS CANNOT
CREATE ENERGY
•  THUS:
– Form and function often reflects
constraint
– Conversion across trophic levels is
less than 100%
2’nd LAW OF
THERMODYNAMICS
•  In all energy exchanges, the potential
energy of the final state will always be
less than the initial state
A SCARY THOUGHT?
•  The universe is moving toward
complete entropy!
TWO FORMS OF ENERGY
“WEALTH”
•  Stored
•  Flow
STORED WEALTH
•  Polysaccarides, fats
A FACT
•  The energy currency used by all cells is
adenosine triphosphate ATP
ATP DRIVES WORK
•  3 examples
ENERGY THROUGH
HYDROLYSIS
+ H20
=
+ ENERGY
A FACT
•  ATP is recycled –  The average human body harbors about 250
grams of ATP but uses close to its own weight
in ATP every day
A FACT
•  ATP is recycled 2 TYPES OF REACTIONS
•  Exergonic
•  Endergonic
TO DRIVE ENDERGONIC
REACTIONS:
•  Couple them to exergonic reactions
ACQUIRING ENERGY FROM
PHOSPHORYLATION
•  fructose + ATP fructose phosphate + ADP
•  glucose + ATP glucose phosphate + ADP
"
HOW TO MAKE SUCROSE
•  glucose phosphate + fructose phosphate
 sucrose + 2 phosphates TWO POINTS TO KEEP
IN MIND
•  Limits to ATP supply
•  Reactions may need activation
GETTING OVER THE
HUMP
•  Reactions may need activation
SOME FACTS
•  Enzymes are specialists.
•  They can facilitate reactions at rates
more than 1,000,000 times faster than
naturally occur
ENZYMES CATALYZE
REACTIONS VIA:
•  Substrate orientation
•  Physical stress
•  Changes in substrate reactivity
BOX ANALOGY
FACILITATOR
TAKING ADVANTAGE OF
ENZYMES
•  Substrate competition - tight bond
•  Substrate competition - classic competition
•  Protein binding
•  ph
•  Temperature
FEEDBACK INHIBITION
•  DEF’N - Key enzyme in a metabolic
pathway is temporarily inactivated
when the concentration of the end
product of that pathway is elevated
CO-FACTORS IN ENZYME
ACTION
•  Non-protein substances that work in
concert with enzymes to facilitate a
reaction