Metabolism refers to the chemical processes that take place inside cells, including thousands of reactions that build up or break down complex compounds. These anabolic and catabolic pathways are concerned with managing the cell's energy and resources. Metabolism involves the conversion of energy from one form to another, as governed by the laws of thermodynamics. ATP acts as the main energy currency, using energy released from its phosphate bonds to power cellular work through exergonic reactions. Enzymes are crucial to metabolism as they catalyze reactions and allow them to proceed faster by lowering their activation energy. Metabolic pathways are regulated through feedback inhibition which turns pathways off once a threshold of end products has been reached.

1. INTRODUCTION TO
METABOLISM

2. • Metabolism = the totality of an organisms
chemical processes
• Inside cells thousands of chemical reactions
occur within microscopic spaces
• Metabolism is concerned with the
management of energy and chemical
resources of the cell

3. • Pathways that build up complex compounds
are called Anabolic
• Pathways that breakdown complex
compounds are called Catabolic
• Often these complimentary reactions are
paired

4. Energy
• Energy is the capacity to do work
• Kinetic energy is the energy of things in
motion
• Potential energy is energy of non-moving
matter; by virtue of its location or
arrangement
• Energy can be converted from one form to
another

5. Thermodynamics
• Thermodynamics is the study of energy
transformations
• 1st Law of Thermodynamics = Energy
cannot be created or destroyed
• 2nd Law of Thermodynamics = Every
energy transfer or transformation increases
the entropy (disorder) in the universe

6. Free Energy
• Free energy is the portion of a system’s
energy that can perform work when temp. is
uniform throughout the system. Ex In a
living cell
• Delta G = Delta H - T Delta S : This is the
free energy equation; This term is very
important it determines whether reactions
will “go” in systems

7. Free Energy Cont.
• Delta G = Delta H - T Delta S ( a triangle
represents delta)
• Delta means “change in”
• G = G final state - G initial state
• T = C + 273
• S = entropy
• H = system’s total energy

8. Reactions in Biological Systems
• Chemical reactions are classified by their
free energy status
• Exergonic reactions = proceed with a net
release of free energy
• Endergonic = absorb energy from the
environment. They need to be provided
“power” to run
• Ex Breakdown of glucose exergonic but
photosynthesis is endergonic

9. ATP and Cellular work
• ATP is a nucleoside that the cell uses to
power the cell. It is the main energy
currency of cells.
• ATP is composed of an adenine, a ribose,
and PO4 group: the tri PO4 tail is unstable
• The bonds can be broken by hydrolysis
• The terminal phosphate is most unstable,
when removed it yields - ( negative) 7.3
kcal of energy.

11. ATP Cont.
• Negative delta Gs mean the reaction is
exergonic ( gives off energy)
• Positive delta Gs mean the reaction is
endergonic ( needs energy to go)
• The cell can couple reaction yielding and
needing ATP to make complex biochemical
pathways go.
• ATP is a renewable resource it is recycled

14. Enzymes
• Most chemical reactions would occur too
slowly in bio systems because the temps are
fairly low
• Enzymes are chemical agents that change
the reaction rate without being consumed or
converted in the reaction process
• Enzymes speed reactions by lowering the
activation energy

17. Enzymes cont.
• Enzymes are very specific
• Enzymes are proteins
• Chemical reactions involve bond a making
and breaking
• The initial energy necessary to start the
reaction is called activation energy
• Enzymes can “ recognize” their substrates
WHY?

18. Enzymes Cont.
• The active site of an enzyme is the pocket
where it attaches to the substrate
• Substrate------Product ( Enzyme) ;
cofactors = helpers
• Factors affecting enzyme function and
stability
– Temp
– pH
– Salinity

21. Inhibitors
• Enzyme inhibition
– Competitive = bind to active site
– Non-competitive = bind to another area

23. Metabolic Control
• Not all metabolic pathways are
simultaneously activated
• Feedback inhibition control is most
common = pathway is turned off by a
specific concentration of the end product