4.4 Overview of Cellular Respiration

KEY CONCEPT The overall process of cellular respiration converts sugar into ATP using oxygen.

4.4 Overview of Cellular Respiration

Cellular respiration makes ATP by breaking down sugars.

• Cellular respiration is aerobic, or requires oxygen.• Aerobic stages take place in mitochondria.

mitochondrion

animal cell

4.4 Overview of Cellular Respiration

• The equation for the overall process is:C6H12O6 + 6O2 6CO2 + 6H2O

• The reactants in photosynthesis are the same as the products of cellular respiration.

4.4 Overview of Cellular Respiration

• Glycolysis must take place before cellular respiration can begin.

– anaerobic process (does not require oxygen)– takes place in cytoplasm– uses 2 ATP molecules to split glucose– glucose is broken down into 2 molecules of pyruvate– produces 4 ATP molecules; therefore net ATP produced = 2 ATP– 2 molecules of NADH produced

4.4 Overview of Cellular Respiration

Before the Kreb’s Cycle can start the following has to take place:

• Pyruvate is broken down before the Krebs cycle.– carbon dioxide is released– NADH is produced and

moves on to the electron transport chain

– coenzyme A (CoA) bonds to a two-carbon molecule and is used to start the Kreb’s Cycle

4.4 Overview of Cellular Respiration

• The Kreb’s Cycle is also known asthe Citric Acid Cycle, b/c citric acidis made and then broken down.

• Takes place in the mitochondrion matrix.• The following are produced from the

breakdown of 1 pyruvate molecule: 3 molecules of CO2

1 molecule of ATP 4 molecules of NADH (which is

sent to the electron transport chain) 1 molecule of FADH2 (which is

sent to the electron transport chain.

Since 2 pyruvates are made during glycolysis, how many of each molecule isproduced? (6 CO2, 2 ATP, 8 NADH, 2 FADH2)

The first MAIN stage of cellular respiration is the Kreb’s Cycle.The Kreb’s Cycle produces energy-carrying molecules (ATP, NADH, FADH2)

4.4 Overview of Cellular Respiration

• The electron transport chain produces up to 32 ATP in addition to water.

– NADH and FADH2 are stripped of electrons which converts them to NAD+ and FAD+. The electrons travel down the ETS and are used to make water and ATP.

– ATP synthase converts ADP into ATP

– Oxygen picks up electrons and H + to make H20 (water).

The electron transport chain is the second main part of cellular respiration.• The electron transport chain uses NADH and FADH2 from the Kreb’s

Cycle to make ATP.

4.4 Overview of Cellular Respiration

Comparing Cellular Respiration and PhotosynthesisPhotosynthesis Cell Respiration

Organelle for Process chloroplasts mitochondrion

Reactants CO2 and H2O C6H12O6 and O2

Electron Transport Chain

Proteins w/in the thylakoid membrane

Proteins w/in the inner mitochondrial membrane

Cycle of Chemical Reactions

Calvin Cycle in the stroma of chloroplasts builds sugars (C6H12O6)

Krebs Cycle in the matrix of the mitochondria

breaks down sugar and other carbon-based

molecules

Products C6H12O6 and O2 CO2 and H2O

Remember photosynthesis absorbs energy and cellular respiration releases it!