Chapter 7 Oxidation and Reduction Introduction to Respiration Day 2.
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Chapter 7 Oxidation and Reduction Introduction to Respiration Day 2
Transcript of Chapter 7 Oxidation and Reduction Introduction to Respiration Day 2.
Chapter 7Oxidation and Reduction
Introduction to RespirationDay 2
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Cellular respiration can best be described as
A. using energy released from breaking high-energy covalent bonds in organic molecules to make ATP.
B. taking electrons from food and giving them to oxygen to make water and using the energy released to make ATP.
C. converting higher-energy organic molecules to lower-energy organic molecules and using the energy released to make ATP.
The Principle of Redox
• Chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions, or redox reactions.
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Oxidation
• In oxidation, a substance loses electrons, or is oxidized.
Redox• In reduction, a substance gains electrons, or is
reduced (the amount of positive charge is reduced).
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• The electron donor is called the reducing agent. (Na)
• The electron acceptor is called the oxidizing agent. (Cl)
becomes oxidized(loses electron)
becomes reduced(gains electron)
Figure 7.UN02
becomes oxidized
becomes reduced
• The electron donor is called the reducing agent. (X)
• The electron acceptor is called the oxidizing agent. (Y)
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Figure 7.3
Reactants Products
Methane(reducing
agent)
Oxygen(oxidizing
agent)
Carbon dioxide Water
becomes reduced
becomes oxidized
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Figure 7.UN03
becomes oxidized
becomes reduced
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Stepwise Energy Harvest via NAD+ and the Electron Transport Chain
In cellular respiration, glucose and other organic molecules are broken down in a series of steps.
Electrons from organic compounds are usually first transferred to NAD, a coenzyme.
As an electron acceptor, NAD functions as an oxidizing agent during cellular respiration.
Each NADH (the reduced form of NAD) represents stored energy that is tapped to synthesize ATP.
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Figure 7.4
NAD
Nicotinamide(oxidized form)
Nicotinamide(reduced form)
Oxidation of NADH
Reduction of NAD
DehydrogenaseNADH
2[H] (from food)
2 e− 2 H
2 e− H
H
H
Figure 7.UN04
NADH passes the electrons to the electron transport chain.
Unlike an uncontrolled reaction, the electron transport chain passes electrons in a series of steps instead of one explosive reaction.
O2 pulls electrons down the chain in an energy-yielding tumble.
The energy yielded is used to regenerate ATP.
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Figure 7.5
Explosiverelease
(a) Uncontrolled reaction (b) Cellular respiration
H2O
Fre
e en
erg
y, G
Fre
e en
erg
y, G
Electro
n tran
spo
rt
chain
Controlledrelease of
energy
H2O
2 H
2 e−
2 H 2 e−
ATP
ATP
ATP
½
½
½H2 O2 O2
O2
2 H
Zombie Ladybug
When a female Dinocampus coccinellae wasp stings a ladybug, it leaves behind a single egg. After the egg hatches, the larva begins to eat its host form the inside out. When ready, the parasite emerges and spins a cocoon between the ladybug’s legs. Though the body is now free of the tormentor, the bug remains enslaved, standing over the cocoon and protecting it form predators.
