Cellular Respiration Part I:
Introduction to Energy Harvesting
Big Idea 2 Energy 2.A.1
• 1. All living systems require constant input of
energy.
2
Curriculum Framework
• f. Cellular respiration in eukaryotes
involves a series of coordinated enzymecatalyzed reactions that harvest free
energy from simple carbohydrates.
3
It sound simple but……
• Why do you have to eat?
– What does it have to do with entropy?
• Why do you have to breathe?
• Can you give an AP Biology level answer to
these questions?
4
What do you know about this molecule?
ATP
• The cell’s energy currency
• Energy is released when a phosphate is
removed from the molecule.
• Respiration fuels the addition of P to ADP
• Unstable, short-term energy storage
High Energy Phosphate Bonds
-
Ribose
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Light
energy
ECOSYSTEM
Photosynthesis
in chloroplasts
CO2  H2O
Cellular respiration
in mitochondria
ATP
Heat
energy
Organic
 O2
molecules
ATP powers
most cellular work
Sequence These From
Greatest To Least Chemical Energy
Greatest to Least
The Principle of Redox
• Chemical reactions that transfer electrons
between reactants are called oxidationreduction reactions, or redox reactions
• In oxidation, a substance loses electrons, or is
oxidized (its oxidation number increases)
• In reduction, a substance gains electrons, or is
reduced (the amount of positive charge is
reduced)
Example
Reactants
Products
becomes oxidized
Energy
becomes reduced
Methane
(reducing
agent)
Oxygen
(oxidizing
agent)
Carbon dioxide
Water
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Oxidation of Organic Fuel Molecules
During Cellular Respiration
• During cellular respiration, the fuel (such as glucose)
is oxidized, and O2 is reduced
becomes oxidized
becomes reduced
Respiration
• Cellular respiration includes both aerobic and
anaerobic respiration but is often refers to aerobic
respiration
• Although carbohydrates, fats, and proteins are all
consumed as fuel, it is helpful to trace cellular
respiration with the sugar glucose
C6H12O6 + 6 O2  6 CO2 + 6 H2O + Energy (ATP + heat energy)
Big Energy Events of Respiration
– Glycolysis (breaks down glucose into two
molecules of pyruvate)
– The citric acid cycle (completes the
breakdown of glucose)
– Oxidative phosphorylation (accounts for
most of the ATP synthesis)
So…..Why do we have to eat?
• Answer the question using your AP Biology
level understanding of energy transfer.
• Be ready to share your answer.
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Created by:
Debra Richards
Coordinator of Secondary Science Programs
Bryan ISD
Bryan, TX