2. Chapter 6: Page 1
• 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. Chapter 6: Page 2
• Pathways that build up complex compounds
are called Anabolic
• Pathways that breakdown complex
compounds are called Catabolic
• Often these complimentary reactions are
paired
4. Chapter 6 Page 3 : 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. Chapter 6 Page 4:
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. Chapter 6 Page 5: 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. Chapter 6 Page 6: Free Energy
Cont.
• Δ G = Δ H - T Δ 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. Chapter 6 Page 7: 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. Chapter 6 Page 8 : 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.
10.
11. Chapter 6 Page 9 : 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
12.
13.
14. Chapter 6 Page 10: 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
15.
16.
17. Chapter 6 Page 11: 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. Chapter 6 Page 12: 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
19.
20.
21. Chapter 6 Page 13: Inhibitors
• Enzyme inhibition
– Competitive = bind to active site
– Non-competitive = bind to another area
22.
23. Chapter 6 page 14 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
