4.4 Overview of Cellular Respiration
Cellular Respiration…• Is a process that makes ATP by
breaking down sugars (glucose).• Cellular respiration is aerobic, or
requires oxygen.
• Three Stages:1.Glycolysis
2.Krebs Cycle3.Electron Transport Chain
Cellular respiration takes place in the mitochondria!!!
Step 1: GLYCOLYSIS
• MUST happen FIRST…REQUIRED for Cellular Respiration.
• Anaerobic process (does NOT require oxygen)
• Takes place in cytoplasm• Enzymes split glucose into two
three-carbon molecules– Pyruvic Acid
• Produces two ATP molecules
Step 2: The Krebs Cycle
• Is the first main part of cellular respiration.
• Produces molecules that carry energy to the second part of cellular respiration.
Stage 2: KREBS CYCLE(Aerobic Pathway)
– takes place in the matrix of the mitochondria
– breaks down three-carbon molecules from glycolysis (Pyruvic Acid molecules)
– Regulated by enzymes– Makes 2 molecules of ATP– Releases carbon dioxide– Transfers energy-carrying molecules to
Electron Transport Chain• NADH & FADH2
6H O2
6CO 2
6O 2
mitochondrionmitochondrion
matrix (area enclosedby inner membrane)
inner membrane
ATP
ATP
energy
energy from glycolysis
2
4
3
and
and
and
Step 3: The Electron Transport Chain
• Second main part of Cellular Respiration
• takes place in the inner membrane of the mitochondria
• Uses energy from Krebs Cycle to drive electron transport chain
• Oxygen enters process• 32-34 molecules of ATP produced• water released as a waste product• Formed when enzyme combines hydrogen and
oxygen
6H O2
6CO 2
6O 2
mitochondrionmitochondrion
matrix (area enclosedby inner membrane)
inner membrane
ATP
ATP
energy
energy from glycolysis
1
2
4
3
and
and
and
Products of Cellular Respiration-including Glycolysis
• 6 molecules Carbon dioxide from the Krebs cycle and Glycolysis
• 6 molecules of water from the electron transport chain
• A net gain of up to 38 ATP molecules for every glucose molecule– 2 from glycolysis– 2 from the Krebs cycle– 32-34 from the electron transport chain
The equation for the overall process of Cellular Respiration is:
C6H12O6 + 6O2 6CO2 + 6H2O + ATP
Glucose + Oxygen Carbon dioxide + Water + Energy
Relationship between Photosynthesis & Cellular Respiration:
• The reactants in photosynthesis are the same as the products of cellular respiration.
Cellular Respiration
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