Cellular Respiration
Cellular Respiration
• Process that makes energy for all life on earth
• It is the transfer of chemical bond energy of
organic molecules to the chemical bond energy of
ATP
• Remember:
– Making chemical bonds stores energy
– Breaking chemical bonds releases energy
• Respiration breaks the bonds of glucose, so it
releases energy
Harvesting energy stored in food
• Cellular respiration
– breaking down food to produce ATP
• in mitochondria
• Oxygen is needed for these
reactions
food
– “aerobic” respiration
– usually digesting glucose
• but could be other sugars,
fats, or proteins
O2
glucose + oxygen  energy + carbon + water
dioxide
C6H12O6 +
6O2
 ATP + 6CO2 + 6H2O
ATP
Both plant and animal cells carry out the final stages of
cellular respiration in the mitochondria.
Intermembrane
Mitochondrion
space
Outer membrane
Plantl Cells
Animal Cells
Inner
membrane
Matrix
Using ATP to do work?
ATP facts:
Can’t store ATP
 too unstable
 only used in the cell
that produces it
 only short term
energy storage
carbohydrates & fats
are long term
energy storage
ATP
Adenosine TriPhosphate
work
Adenosine DiPhosphate
ADP
A working muscle recycles over
10 million ATPs per second
ATP Factoid
• On average, the human body contains 250
grams of ATP
• The amount of ATP used by the human body
in a day equals the body weight of the
individual.
ADP vs. ATP
A Body’s Energy Budget
1
eat
food
make energy
ATP
2
synthesis
(building)
3
storage
{
{
{
• energy needed
even at rest
• activity
• temperature
control
• growth
• reproduction
• repair
• glycogen
(animal starch)
• fat
Other Energy Molecules…
• NAD+ and FAD
– Hydrogen and electron carriers
– Bring hydrogen/electrons to the electron transport
chain where they are used to make more ATP
• Hydrogen and Electrons are sources of potential energy
• Energy can be released from these molecules later on to
make ATP
– Low
– NAD+
– FAD


High
NADH
FADH2
Cellular Respiration
• Occurs in 3 Distinct Phases
– The first stage, glycolysis, is anaerobic—no
oxygen is required.
– The last two stages are aerobic and require
oxygen to be completed.
SUMMARY EQUATION:
STAGES OF CELLULAR RESPIRATION
• Respiration occurs in three main stages
High-energy electrons
carried by NADH
GLYCOLYSIS
Cytoplasmic fluid
KREBS
CYCLE
ELECTRON
TRANSPORT CHAIN
Mitochondrion
Glycolysis
Glyco=sweet, sugar
lysis = to split
Glycolysis: a series of chemical
reactions in the cytoplasm of a cell
that break down glucose, a six-carbon
compound, into two molecules of
pyruvic acid, a three-carbon
compound
• Pyruvic acid: a 3 carbon compound
made during glycolysis by splitting
a glucose molecule.
• produces two ATP molecules for
each glucose molecule broken
down.
• 2 molecules of NADH are formed
Detailed View
Glycolysis Summary
• Produces 2 ATP
– 2 ATP were needed for the reaction
– 4 ATP were made in the reaction
• Creates 2 NADH molecules
– Passed to Electron Transport Chain
• Glucose (6 C’s) has been broken
down to form 2 molecules of
pyruvic acid (3 C’s)
– Will be converted into Acetyl CoA
The Transition Phase
*(we’ll include this as part of Kreb’s)
• Before Krebs Cycle and electron transport chain can
begin, pyruvic acid undergoes a series of reactions in
which it gives off a molecule of CO2 and combines with a
molecule called coenzyme A to form acetyl-CoA. (a
molecule made from pyruvic acid )
Acetyl CoA
(acetyl
coenzyme A)
Pyruvic
acid
CO2
The Krebs Cycle
• Series of reactions that
occurs in mitochondrial
matrix
– Breaks pyruvic acid down into
CO2, releasing energy
• For every one turn of the
cycle, one molecule of ATP,
two molecules of carbon
dioxide, 4 NADH, 1 FADH2 are
produced.
• Per molecule of glucose,
Kreb’s creates:
• 2 ATP
• 8 NADH
• 2 FADH2
• 4 CO2
CO2
The electron transport chain (ETC)
• Set of reactions taking place in the inner
mitochondrial membrane that convert the NADH
and FADH2from glycolysis and the krebs cycle to
convert ADP into ATP.
– In the electron transport chain, the carrier molecules
NADH and FADH2 give up electrons that pass through
a series of reactions. Oxygen is the final electron
acceptor forming water.
• This sets up a H+ (proton) gradient
• Allow the protons to flow through ATP synthase
which synthesizes ATP (ADP + Pi = ATP)
ETC continued…
• The electron transport chain adds 32 ATP
molecules to the four already produced during
glycolysis & Krebs cycle
• Occurs in the inner mitochondrial membrane
ETC
• Located in the inner Mitochondrial membrane
• Produces 32 ATP
• For each pair of Hydrogen atoms brought in
by:
– NADH: 3 ATP molecules are made
– FADH2: 2 ATP molecules are made
In summary, what do we need to make
energy?
• The “Furnace” for making energy
– mitochondria
• Fuel
– food: carbohydrates, fats, proteins
• Helpers
– oxygen
– enzymes
food
• Product
enzymes
– ATP
• Waste products
– carbon dioxide
• then used by plants
– water
O2
ATP
CO2
H2O
Summary Facts : Cellular Respiration
• Reactants/Raw materials : oxygen + sugar
(glucose, starch, food, fats)
• Energy Source: chemical bond energy of organic
comp’ds
• Products Made: carbon dioxide, water, ATP
(energy)
• When does it occur?: all the time, constantly,
24/7
• Location in the Cell: mitochondria
• Organisms that use it: all living things