Harvesting Energy
Glycolysis and Cellular Respiration
Energy from Glucose
• __________and _______________
break glucose and other carbon
compounds apart.
• Energy released from broken bonds is
harnessed to make ____ to run cell
processes.
• ALL Eukaryotic organisms (including
plants) carry out cellular respiration ____
_____ _____.
Cellular respiration takes place in the mitochondria.
outer
membrane
mitochondrion
intermembrane
space
inner
membrane
cristae
matrix
Remember ATP?
Adenosine triphosphate,
the universal energy
carrier, is a single
nucleotide (adenine)
with two extra
phosphate groups
attached.
ATP is produced in
great quantities by
mitochondria.
Review: ATP is produced and used in coupled reactions
______________
(glucose breakdown)
_____________
(ATP synthesis)
______________
(ATP breakdown)
ADP + heat
net ____________
“downhill” reaction
_______________
(protein synthesis)
Overview
glucose
(cytosol)
2 NADH
glycolysis
2 ATP
2 pyruvate
____________ splits
sugar into two 3carbon chains
(pyruvate), producing
2 ATPs
2 NADH
(mitochondrion)
2 acetyl CoA
6 NADH
Krebs
(citric acid)
cycle
2 ATP
electron transport chain
32 or 34
ATPs
2 FADH2
________________
breaks the sugar
down further,
producing 32-34
ATPs.
Total 36 or 38
ATPs
NADH and FADH (derived from vitamins B3 and
B2) act as electron carriers.
in cytosol–
no oxygen required
glucose
if no O2 available
fermentation
in mitochondria–
oxygen required
cellular respiration
Glycolysis
in cytosol
2 ATP
4
2 ADP
ADP
4 ATP
2
glucose
2
G3P
fructose
bisphosphate
1 Glucose activation
__________ is split in half.
2 ATPs are used.
2 NAD+
pyruvate
2 NADH
2 Energy harvest
Net gain of 2 ATPs
End product is ________
Glycolysis Animation
Role of B Vitamins
Cellular respiration begins with moving the products of
glycolysis into the mitochondrion.
1 Formation of
acetyl CoA
coenzyme A
3 _______
3 NAD+
_______
____ coenzyme
A
CoA
__________
________
NAD+
FAD
2 Krebs
cycle
_______
In cytosol
2
ADP
_______
In mitochondrion
______
Krebs Cycle Animation
Electron carriers from the Krebs cycle are used to power
an electron transport chain and proton pump.
High-energy electron carriers
from acetyl CoA formation, Krebs
cycle, and glycolysis feed into the ETC.
FADH2
NADH
Flow of H+ down
concentration gradient
powers ATP synthesis.
Oxygen is required
to accept energydepleted electrons.
1/2O2
2e–
FAD
NAD
2H+
H2O
ADP
+
Pi
ATP
matrix
inner
membrane
Energy from
high-energy electrons
powers active
transport of H+ by ETC.
intermembrane
space
High H+ concentration is
generated by active transport.
H+ channel is coupled to
ATP synthesizing enzyme.
Electron Transport Chain Animation
Main points of cellular respiration
• Cellular respiration takes place in the
mitochondria.
• The product of glycolysis is broken down
completely, releasing CO2 as a waste
gas.
• The electron transport chain/proton
pump complex uses energized electrons
to produce up to 36 ATPs from each
molecule of glucose.
Mitochondria animation on XVIVO
glucose
(cytosol)
2 NADH
glycolysis
2 ATP
In the absence
of _________,
ethanol + CO
cellular
respiration
cannot continue.
Pyruvate from
glycolysis is
fermented,
producing ____
____ or ______.
lactate
Cellular
respiration
requires ______
to pick up
electrons and
protons at the
end of an
electron
transport chain
2 pyruvate
fermentation
(no O2)
or
2
cellular respiration
2 CO2
2 NADH
2 acetyl CoA
Krebs
(citric
acid)
cycle
6 NADH
2 FADH2
4 CO2
2 ATP H O
2
1/2O2
2H+
2e–
32 or 34
ATPs
electron transport chain
(mitochondrion)
If the mitochondria can’t accept pyruvate, NADH from
glycolysis accumulates, depleting NAD+. Fermentation
uses excess NADH to convert pyruvate to lactic acid or
ethanol.
regeneration
NAD+
NADH
2
(glycolysis)
glucose
2
ADP
2
NADH
NADH
NAD+
2
(fermentation)
pyruvate
lactate
ATP
Other
monomers can
be broken down
for energy as
well.
(cytosol)
fats
complex
carbohydrates
glucose
glycerol
proteins
amino
acids
Glycolysis
fatty acids
pyruvate
Fatty acids have
more energy per
gram than sugars,
so are preferred
as energy storage.
acetyl
CoA
While brain cells
usually must have
glucose, other
cells can use fatty
acids and amino
acids for energy.
Krebs
cycle
electron
carriers
Electron
transport chain
(mitochondrion)
synthesis
breakdown
Amino acids must
be stripped of
nitrogen first,
which is disposed
of in the kidneys.
What if you take in more monomers than you
need to produce ATP?
Simple S ugars
Acetyl group
Fatty Acids
Fats
Simple sugars are broken apart in glycolysis. If the
mitochondria does not need Acetyl CoA, the acetate is
released and can be used to synthesize fatty acids to
make fats for storage.
Carbon
Backbones
Amino Acids
Fatty Acids
Fats
NH 3
Urea
Amino acids not needed for protein synthesis are
stripped of their amine groups. The remaining carbon
backbone can either be used to make Acetyl CoA, or
can be used to synthesize fatty acids.
Recap
• Cellular respiration breaks organic
compounds down into inorganic compounds.
• In the process, chemical energy in
compounds such as sugar is converted to
chemical energy in ATP.
• ATP is used to run cellular processes.
• ALL Eukaryotic organisms carry out cellular
respiration.