Setting the Stage – PPT 1
NOW Required!
AP Biology
What’s the point?
ATP
The Point is to Make ATP!
AP Biology
Harvesting stored energy
 Energy is stored in organic molecules

heterotrophs eat food (organic molecules)
 digest organic molecules
 serve as raw materials for building & fuels for energy
 controlled release of energy
 series of step-by-step enzyme-controlled reactions

“burning” fuels
 carbohydrates, lipids, proteins, nucleic acids
AP Biology
2005-2006
Harvesting energy stored in glucose
 Glucose is the model
respiration

catabolism of glucose to produce ATP
glucose + oxygen  carbon + water + energy
dioxide
C6H12O6 +
6O2
 6CO2 + 6H2O + ATP + heat
combustion = making heat energy
by burning fuels in one step
respiration = making ATP (& less heat)
by burning fuels in many small steps
ATP
fuel
AP Biology
(carbohydrates)
CO2 + H2O + heat
CO2 + H2O + 2005-2006
ATP (+ heat)
How do we harvest energy from fuels?
 Digest large molecules into smaller ones

break bonds & move electrons from one
molecule to another
 as electrons move they carry energy with them
 that energy is stored in another bond, released
as heat, or harvested to make ATP
loses e-
gains e-
+
oxidized
+
oxidation
AP Biology
e-
reduced
+
–
ereduction
2005-2006
How do we move electrons in biology?
In living systems, electrons do not
move alone
 electrons move as part of H atom
loses e-
gains e-
oxidized
+
+
oxidation
reduced
+
–
H
reduction
H
oxidation
C6H12O6 +
AP Biology
H
6O2
 6CO2 + 6H2O + ATP
reduction
2005-2006
Coupling oxidation & reduction
 Redox reactions in respiration

release energy as breakdown molecules
 break C-C bonds
 strip off electrons from C-H bonds by removing H atoms
 C6H12O6  CO2 = fuel has been oxidized
 electrons attracted to more electronegative atoms
 in biology, the most electronegative atom?
 O2  H2O = oxygen has been reduced
 release energy to synthesize ATP
 O2
oxidation
C6H12O6 +
AP Biology
6O2
 6CO2 + 6H2O + ATP
reduction
2005-2006
Oxidation & reduction
 Oxidation
 Reduction
removing H
 loss of electrons
 releases energy
 exergonic

adding H
 gain of electrons
 stores energy
 endergonic

oxidation
C6H12O6 +
6O2
 6CO2 + 6H2O + ATP
reduction
AP Biology
2005-2006
Moving electrons in respiration
 Electron carriers move electrons by shuttling
H atoms around
 NAD+  NADH (reduced)
 FAD+2  FADH2 (reduced)
NAD
nicotinamide
Vitamin B3
O–
O – P –O
O
phosphates
O–
O – P –O
O
AP Biology
H
reducing power!
NADH
O
H H
C NH2
N+
+
adenine
ribose sugar
H
O
C NH2
reduction
O–
–
–
oxidation O P O
O
O–
– P –O
O
stores energy
O
as a reduced
molecule
N+
How efficient!
Build once,
use many ways
2005-2006
Overview of cellular respiration
 4 metabolic stages

Anaerobic respiration
 1. Glycolysis
 respiration without O2
 in cytosol

Aerobic respiration
 respiration using O2
 in mitochondria
 2. Pyruvate oxidation
 3. Kreb’s cycle
 4. Electron transport chain
C H O6 +
AP Biology
6 12
6O2
(+ heat)
 6CO2 + 6H2O + ATP 2005-2006
What’s the point?
ATP
The Point is to Make ATP!
AP Biology
2005-2006
Any Questions??
AP Biology
2005-2006