To remain alive, living things must acquire energy and then
put that energy into a form they can use
Oxygen
Heat
Metabolism
• Life is a combustion process
• You are using oxygen to burn fuel (food) to create energy (and waste
heat)
Hydrocarbon Fuel + O 2
CO 2 + H 2 O
Heat
Combustion in a Pop Bottle Demonstration
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.
 Alcohol Fermentation
 Uses NADH to convert pyruvic acid into alcohol
 This produces a steady stream of ATP and CO2
 Lactic Acid Fermentation:
 Uses NADH to convert pyruvic acid to lactic acid
 This produces a steady stream of ATP
 One carbon is broken off of each pyruvic acid moelcule
 This 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
 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-)
 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.
Electrons 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
ATP Yield= 36
You 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.
 Function
 cellular respiration
 generate ATP
 from breakdown of sugars, fats
& other fuels
 in the presence of oxygen
 break down larger molecules into smaller to generate energy =
catabolism
 generate energy in presence of O2 = aerobic respiration
 2 Membranes to increase surface area
 Smooth outer membrane
 Highly folder inner membrane
 The Cristae