Cellular Respiration

“What a Sweet Process!”

Cellular Respiration

Defined as: the process by which mitochondria break down food molecules to produce ATP

C6H12O6 + 6O2 6CO2 + 6H2O + energy (ATP)

Review of Mitochondria Review of Mitochondria StructureStructure

SmoothSmooth outer outer MembraneMembrane

FoldedFolded inner inner membranemembrane

Folds called Folds called CristaeCristae Space inside cristae Space inside cristae

called the called the MatrixMatrix

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 CO2

Electron Transport ChainTakes place on the inner

mitochondrial membrane, makes 32 ATP

Creates a pool of H+ ions that create a gradient (outer matrix)

ATP Synthase forms ATPWater is made from e-, H+, and O2

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 O2)

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 bacteriaAlcoholic: 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 FermentationMakes only 2 ATPAlso gives off CO2 and Alcohol!

Used for making bread dough rise during baking

Also, used for wine, champagne, etc.

Final ResultIn the presence of

oxygen, cellular respiration breaks down glucose to get up to 38 ATP (66% efficient)

A different look…

http://www.qcc.cuny.edu/BiologicalSciences/Faculty/DMeyer/respiration.html

http://www2.nl.edu/jste/electron_transport_system.htm

http://www.wiley.com/legacy/college/boyer/0470003790/animations/electron_transport/electron_transport.htm