Transcript Energy Transfer: Cellular Respiration

Energy Transfer:
Cellular Respiration
G.Burgess
Updated 2010.
Release of stored energy
 Two forms:
 Anaerobic: releases energy when oxygen is not
present = fermentation
 Aerobic: releases energy using oxygen
Anaerobic Respiration

Fermentation:
 performed by yeast: converts glucose to carbon dioxide
and ethanol when releasing energy.
 2ATP + Glucose  2 pyruvic acid molecules (3C molecules)
+ 4ATP
 The pyruvic acid is then converted to ethanol and CO2
 This conversion releases H+ to NAD+ molecules
 Bacteria also perform anaerobic respiration
 Convert pyruvic acid to lactic acid.
 This is a similar reaction that occurs in over stressed
muscle cell.
Aerobic Respiration


Most efficient for ATP production
Three main processes;
 Glycolysis: cytoplasm
 Krebs Cycle: outer membrane of mitochondria
 Electron Transport Chain: inner membrane of
mitochondria

Reactants: Glucose and oxygen

Products: ATP + CO2 + H2O
Glycolysis




Anaerobic phase
requires 2 ATP
Glucose is converted to pyruvic acid releasing H+ and 4 ATP
H+ is picked up by NAD+ (nicotinamide adenine dinucleotide)
and transported to the electron transport chain
http://librar
y.thinkque
st.org/278
19/media/
glycolysis.
gif,
accessed
Oct.14,
2007
Krebs Cycle








AKA: Citric Acid Cycle
Changes pyruvic acid to different carbon molecular forms.
The changing of the molecule releases H+’s, GTP and CO2.
**Each time CO2 is released, oxygen was used.
NAD and FAD are ion acceptor molecules in this stage
NAD and FAD transport H+’s to the electron transport chain.
GTP is converted to ATP for useable molecular energy.
2 ATP are formed
Electron Transport Chain
 AKA: oxidative phosphorylation
 Electron acceptor molecules transport electrons (H ions)
to the inner membrane of the mitochondria
 The electrons are passed from one electron acceptor to
another stronger one.
 Each time the electron is passed energy is given off
 Energy is collected as ADP joins P to form ATP.
 Approx. 32 ATP are formed
Net Energy
 **Not all the energy formed is converted to ATP
 Energy not collected by ATP is released as heat
energy.
 This is partly the reason why we are warm blooded
organisms.