Cellular Respiration “What a Sweet Process!”

Defined as: the process by which mitochondria break down food molecules to produce ATP C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + energy (ATP)

Review of Mitochondria Structure Smooth outer Membrane Smooth outer Membrane Folded inner membrane Folded inner membrane Folds called Cristae Folds called Cristae Space inside cristae called the Matrix Space inside cristae called the Matrix Copyright Cmassengale

Cellular Respiration Can be broken into 3 steps: 1) Glycolysis 2) Krebs (Citric Acid) Cycle 3) Electron Transport Chain

Glycolysis (Glyco-lysis) Takes place in cytoplasm Breaks down glucose (6 C’s) into 2 compounds each with 3 C’s (Pyruvic acid) Net ATP= 2 This step is necessary b/c glucose is too big to fit through the mitochondrial membrane!

Krebs Cycle Pyruvic acid enters the mitochondria Pyruvic acid is broken down to produce 2 ATP molecules and CO 2

Electron Transport Chain Takes place on the inner mitochondrial membrane, makes 32 ATP Creates a pool of H+ ions that create a gradient (outer matrix) ATP Synthase forms ATP Water is made from e-, H+, and O 2 to keep the chain going!

Why the three steps? If cellular respiration took place in just one step, all of the energy from glucose would be released at once and most of it would be lost in the form of light and heat. It can't simply start a fire - it has to release the explosive chemical energy in food molecules a little bit at a time.

Aerobic Process = Requires Oxygen Anaerobic Process = Doesn’t Require Oxygen The preferred pathway is aerobic in humans, it yields far more ATP! (38 vs. 2) ATP production depends on oxygen availability!

Review

Alternate Route! Fermentation: anaerobic (no O 2 ) process that continues making ATP temporarily in the cytoplasm until oxygen is available again 2 types:  Lactic Acid: can occur in mostly animals and some bacteria  Alcoholic: occurs in yeast cells

Lactic Acid Fermentation Makes only 2 ATP! Builds up lactic acid in muscles making the “burning” sensation while working out!

Alcoholic Fermentation Makes only 2 ATP Also gives off CO 2 and Alcohol! Used for making bread dough rise during baking Also, used for wine, champagne, etc.

Final Result In the presence of oxygen, cellular respiration breaks down glucose to get up to 38 ATP (66% efficient)

A different look… nces/Faculty/DMeyer/respiration.html nces/Faculty/DMeyer/respiration.html port_system.htm port_system.htm oyer/ /animations/electron_ transport/electron_transport.htm oyer/ /animations/electron_ transport/electron_transport.htm