To remain alive, living things must acquire energy and then put that energy into a form they can use

Deriving Energy From Food

The Fire of Life• Life is a combustion process• You are using oxygen to burn fuel (food) to create energy (and

waste heat)

Oxygen

Heat

Metabolism

You Consume O2 & Food to Produce Energy

Hydrocarbon Fuel + O2 CO2 + H2O

Heat

Combustion in a Pop Bottle Demonstration

Different Fuels (Foods) Produce Different Amounts of Energy

Lipids (fats) = 9.3 kcal/gram Protein = 4.1 kcal/gram

Carbohydrates = 4.1 kcal/gram

Add 2 ATP to a 6 Carbon glucose molecule creating 2 3 carbon pyruvic acid molecules and 4 ATP

This creates a Net Yield of 2 ATP Occurs in the cytoplasm of all tissue cells, but is also

important in: Tissues with no mitochondria: mature RBCs, cornea and lens. Tissues with few mitochondria: Testis, leucocytes, medulla of the

kidney, retina, skin and gastrointestinal tract. Tissues undergo frequent oxygen lack: skeletal muscles especially

during exercise.

Glycolysis:

Alcohol FermentationUses NADH to convert pyruvic acid into alcohol

This produces a steady stream of ATP and CO2Lactic Acid Fermentation:

Uses NADH to convert pyruvic acid to lactic acid

This produces a steady stream of ATP

Fermentation

One carbon is broken off of each pyruvic acid moelculeThis carbon combine with oxygen and is released as

carbon dioxide waste.The remaining 2 2 carbon acetic acid molecules

combine with an enzyme (coenzyme A) forming acetyl CoA.

Acetyl CoA gives its 2 carbons to a 4 carbon citric acid molecule forming a 6 carbon molecule.

One carbon is broken off at each step releasing CO2 and forming NADH and FADH2 (another electon carrier).

2 cycles are necessary to metabolize 1 glucose molecule

The Krebs Cycle:

GLUCOSE is oxidized by a molecule which is in turn oxidized by another on down the hill.

Molecules that shuttle electrons down the hill ELECTRON CARRIERS

Many of these electrons are bound as Hydrogen (1p+ and 1e-)

The Role of Electron Carriers

NAD+ is positive when it is empty (not carrying electrons)

It picks up a Hydrogen atom and an electron.

This makes it NADH (neutral)Because it took an electron from another substance

it is reduced and the substance that it took electrons from is oxidized

NADH moves downhill and drops off its electron passengers with substances that have a greater attraction for them.

NAD+: an electron carrier

The Electron Transport ChainElectrons fall down the energy hill to drive the uphill production of ATP

Electron carriers NADh and FADH2 bring electrons and Hydrogens to ETC (in inner membrane of the mitochondria)

The electron carriers are reduced when they give their electrons over to the ETC.

Energy is released as the electrons move downhill

The hydrogen bind with the final acceptor O2 forming water that is released as water vapor in the breath

The Electron Transport Chain:

Cellular Respiration ATP Yield= 36

The MitochondriaYou got your mitochondria from your mother in the egg cell from which you came. Mitochondria have their own DNA which can be used to trace your mother's mother's mother's mother's mother back through thousands of years. Thanks, Mom.

Functioncellular respirationgenerate ATP

from breakdown of sugars, fats & other fuels

in the presence of oxygenbreak down larger molecules into smaller to generate

energy = catabolismgenerate energy in presence of O2 = aerobic

respiration

The Mitochondria

2 Membranes to increase surface areaSmooth outer membraneHighly folder inner membrane

The Cristae

Mitochondrial Structure