Cellular Respiration:
Harvesting Chemical Energy
Respiration is the process of
extracting stored energy from
glucose to make ATP.
Cellular Respiration
Equation
C6H12O6 + 6 O2
6 CO2 + 6 H2O and energy
As a result of respiration, energy
is released from the chemical
bonds found in complex organic
molecules (food).
Aerobic Respiration
Aerobic
Respiration is
respiration which takes place
in the presence of oxygen
Respiration is controlled by Enzymes
…rate is controlled by enzymes
Cell Respiration
is divided into 3 stages.
(components)
1. Glycolysis
2. Krebs Cycle
3. Oxidative Phosphorylation
Glycolysis
Glyco-
glucose, -lysis: to split
Universal step in all forms of
respiration
Likely used to supply energy for
the ancient cells.
Glycolysis
Function
- To split glucose and
produce NADH, ATP and
Pyruvate (pyruvic acid).
Location - Cytoplasm.
Occurs in 9 steps…. 6 of the
steps use magnesium Mg as
cofactors.
NAD+
Energy carrier
Nicotinamide
Adenine
Dinucleotide
NAD+ + 2 eNADH
NAD+ = oxidized form
NADH = reduced form
Requirements for Glycolysis
Glucose
2
ATP…. As activation energy
4 ADP
2 NAD+
Enzymes
The Products of
Glycolysis
2
Pyruvic Acids (a 3C acid)
4 ATP
2 NADH
Net Energy Result
2
ATP per glucose
2 NADH
In
summary, glycolysis takes
one glucose and turns it into 2
pyruvate, 2 NADH and a net of 2
ATP.
Krebs Cycle
Also called: Citric Acid Cycle
or Tricarboxylic Acid Cycle
Function:
Oxidize pyruvic acid to CO2
Produce:
3NADH, 1FADH2 and 1ATP
Location:
Mitochondria matrix
Formation of Acetyl CoA:
Acetyl CoA is formed when the pyruvate , from
glycolysis, combines with Coenzyme A… tis
takes place in the matrix.
Requirements for Krebs Cycle
Pyruvic
acid (3C acid)
Coenzyme A
3 NAD+
1 ADP
1 FAD
Double this list for each
glucose.
Products of Krebs Cycle
3
CO2
Acetyl CoA
3 NADH
1 ATP
1 FADH2
Double this list for each
glucose.
Krebs Cycle
Produces
most of the cell's
energy in the form of NADH and
FADH2… not ATP
Does NOT require O2
The CO2 produced by the Krebs
cycle is the CO2 animal exhale
when they breathe.
Oxidative Phosphorylation
Process
of extracting to energy
from NADH and FADH2 to form
ATP.
Function: Convert NADH and
FADH2 into ATP.
Location: Mitochondria cristae.
Oxidative Phosphorylation
NADH
ADP
O2
or FADH2
Oxidative Phosphorylation
Requires
the Electron Transport
Chain… the Electron Transport
Chain is a collection of proteins,
embedded in the inner
membrane, used to transport the
electrons from NADH and FADH2
Cytochrome c
 Cytochrome
c: is one of the proteins
of the electron transport chain…
often used by geneticists to
determine relatedness… exists in all
living organisms.
 The Cytochromes alternate between
RED and OX forms and pass
electrons down to O2
ATP Yield
Each
NADH energizes 3 ATP
Each FADH2 energizes 2 ATP
Chemiosmotic
Hypothesis
ETC
energy is used to move
H+ (protons) across the
cristae membrane.
ATP is generated as the H+
diffuse back into the matrix
through ATP Synthase
ATP Synthase
Uses
the flow of H+ to make
ATP.
Works like an ion pump in
reverse, or like a waterwheel
under the flow of H+ “water”.
Alcoholic Fermentation
Carried
out by yeast, a kind
of fungus.
Alcoholic Fermentation
Uses
only Glycolysis.
An incomplete oxidation energy is still left in the
products (alcohol).
Does NOT require O2
Produces ATP when O2 is not
available.
Lactic Acid
Fermentation
Uses
only Glycolysis.
An incomplete oxidation energy is still left in the
products (lactic acid).
Does NOT require O2
Produces ATP when O2 is not
available.
Lactic Acid
Fermentation
Done
by human muscle cells
under oxygen debt.
Lactic Acid is a toxin and
causes soreness and
stiffness in muscles.
Fermentation Summary
Way
of using up NADH so
Glycolysis can still run.
Provides ATP to a cell even
when O2 is absent.
Aerobic vs Anaerobic
Aerobic
- Respiration with O2
Anaerobic - Respiration without O2
Aerobic - All three Respiration steps.
Anaerobic - Glycolysis only.
Strict vs. Facultative
Respiration
Strict
- can only carry out
Respiration one way…
aerobic or anaerobic.
Facultative - can switch
respiration types depending
on O2 availability. Ex - yeast
ATP yields by Respiration type
Anaerobic
- Glycolysis only
Gets 2 ATPs per glucose.
Aerobic - Glycolysis, Krebs, and
Oxidative Phosphorylation
(electron transport chain)
Generates many more ATPs per
glucose.
Aerobic ATP yield
Glycolysis
- 2 ATPS, 2
NADHs
Krebs - 2 ATPS, 8 NADHs,
2 FADH2
Each NADH = 3 ATP
Each FADH2 = 2 ATP
ATP Sum
10



NADH x 3 = 30 ATPs
2 FADH2 x 2 =
4 ATPs
2 ATPs (Gly) = 2 ATPs
2 ATPs (Krebs) = 2 ATPs
Max
= 38 ATPs per glucose
However...
Some
energy is used in
shuttling the NADH from
Glycolysis into the
mitochondria.
Actual ATP yield ~ 36/glucose
Yeast
Would
rather do aerobic
Respiration; it has 18x more
energy per glucose.
But, anaerobic will keep you
alive if oxygen is not present.
Importance of Respiration
Alcohol
Industry - almost
every society has a
fermented beverage.
Baking Industry - many
breads use yeast to provide
bubbles to raise the dough.
Matching
Sugar Cane
Barley
Grapes
Juniper Cones
Agave Leaves
Rice
Potatoes
Gin
Saki
Tequila
Vodka
Beer
Wine
Rum
Question
Why
is the alcohol content of
wine always around 12-14%?
Alcohol is toxic and kills the
yeast at high concentrations.
Swiss Cheese
Holes
are bubbles of CO2
from fermentation.
Summary
Know
the 3 main reactions of
Respiration and the 4
required items for each.
Exergonic/Endergonic
Biological Examples
Exergonic
- respiration
Endergonic - photosynthesis
Cell - Types of Work
Mechanical
- muscle
contractions
Transport - pumping across
membranes
Chemical - making polymers
Cells use ATP as their
energy source
Adenosine
Made
Triphosphate
of:
- Adenine (nitrogenous base)
- Ribose (pentose sugar)
- 3 phosphate groups
Adenine
Phosphates
Ribose
Key to ATP
Is
in the high energy bonds
between the three phosphate
groups.
Negative charges on the
phosphate groups repel each
other and makes the
phosphates unstable.
ATP Cycles
Energy
released from ATP
drives anabolic reactions.
Energy from catabolic
reactions “recharges” ATP.
ATP
ATP Cycle
ADP + P + Energy
ATP in Cells
A
cell's ATP content is
recycled every minute.
Humans use close to their
body weight in ATP daily.
No ATP production equals
quick death.