Cellular Respiration
Prior Knowledge
 ATP is the basic form of energy used for cellular respiration
 Energy is released from ATP by removing the phosphate off the end
ATP Structure
Respiration Equation
In this equation, the glucose is OXIDEZED, creating CO2
The 02 is REDUCED, creating H20
What is Cell Respiration?
Respiration is the reactions that occur in the mitochondria, in which the biochemical
energy held in glucose is converted into ATP.
The three processes that make up respiration include…
 Glycolysis
 The Krebs/Citric Acid Cycle
 Electron Transport Chain (oxidative phosphorylation)

1. Glycolysis
Glycolysis is a series of reactions that leads to the oxidative breakdown of glucose
into two molecules of pyruvate and the production of ATP, and the reduction of
NAD+ into NADH. This occurs in the cytoplasm.
 USES: 1 Glucose 2 NAD+
 PRODUCES: 2 Pyruvate, 2 ATP, 2 NADH
 Two Major Phases
o Energy Investment Phase (2 ATP used)
o Energy Payoff Phase (4 ATP and 2 NADH formed)

After entering the mitochondria, the Pyruvate must be converted into Acetyl
CoA in order to enter the citric acid cycle.
o This produces 2 NADH
2. Citric Acid or Krebs Cycle
In one single rotation of the cycle (Remember it goes through 2 cycles, one for each
pyruvate), the cycle creates
 NADH- 3 molecules (6 total per one molecule of glucose)
 FADH2- 1 molecule (2 per glucose)
 ATP/GTP- 1 molecule (2 per glucose)
These products will then travel to the Electron Transport Chain to drive the
synthesis of ATP molecules through oxidative phosphorylation
3. Electron Transport Chain
The electron transport chain takes the energy of the electrons stored in NADH and
FADH2 to create a proton gradient that will create ATP. This occurs in the inner
mitochondrial membrane.
 NADH and FADH2 are passed through electron acceptors as they move
towards the final acceptor, oxygen. Proteins pump H+ from the
mitochondrial matrix to the inter-membrane space
 H+ moves back through ATP synthase
o Uses exergonic flow to drive phosphorylation of ATP
This process of using energy in a H+ gradient to drive cellular work is known as
chemiosmosis
 This energy aids in redox reactions
 The gradient is responsible for a proton-motive force
Anaerobic Respiration
 Does NOT use oxygen

Anaerobic respiration still uses the ETC, but the final acceptor is not oxygen,
instead it may be sulfate, etc.
o Fermentation uses substrate-level phosphorylation, not the ETC
 Alcohol fermentation= pyruvate releases CO2 to form ethanol
in two steps
 Lactic acid fermentation= pyruvate forms lactate, allowing no
CO2 to be released, yet a reduction of NADH