Download GLYCOLYSIS

Cellular Respiration:
Harvesting Chemical
Energy
Chapter 6
Energy Flow in Ecosystems
• Photosynthesis
captures and store
sunlight energy as
glucose
• Cellular Respiration
release energy to
cell to do work.
Respiration is the complement to
Photosynthesis, completing a cycle:
Photosynthesis & Respiration
SUNLIGHT
PHOTOSYNTHESIS
6CO2 + 6H2O
C6H12O6 + 6O2
AEROBIC RESPIRATION
The products of photosynthesis
are the reactants for respiration
Controlled
Uncontrolled
The Powerful Mitochondria
• Provide the cell with usable energy as ATP
• Cells with high energy demands make more
mitochondria
• Muscle cells have very high number of
mitochondria
• We breath to get oxygen to our mitochondria
and to to rid ourselves of the carbon dioxide
the mitochondria produce
• The blood carries these gasses to our lungs
for gas exchange by diffusion
• The more energy you burn, the more you
breath out
ATP : Cellular unit of energy
ATP
ADP + Pi
The Reaction for Respiration:
• The carbon atoms we eat in glucose we
breath out as carbon dioxide
• The oxygen we breath in becomes
water in our bodies
C6H12O6 + 6O2
glucose
oxygen
6CO2 + 6H2O
carbon
water
dioxide
The reverse of the equation for photosynthesis
Reactants and Products
• The carbon atoms we eat in glucose we
breath out as carbon dioxide
• The oxygen we breath in becomes
water in our bodies
Thought questions
• What cells have very
high number of
mitochondria ?
• Why do we breath?
• We breath to get _____ into our mitochondria
and to get rid of the _______the mitochondria
produce
• How do these gasses move in the body?
• How does your breathing relate to energy use?
GLUCOSE
The common
food molecule
Respiration is a three step process:
In Cytoplasm:
• Step 1 Glycolysis
– breaks glucose into 2 pyruvate molecules
– Makes 2 ATP
In Mitochondrion:
• Step 2 Krebs cycle
– Completely breaks all c-c bonds
– Primes the proton gradient
– Makes 2 ATP
• Step 3 Electron transport chain
– Makes ATP by chemiosmosis
– Needs O2
– Makes 32-34 more ATP
3 Steps to Cellular respiration
Respiration is a controlled release of usable
energy, in the form of ATP
Step 1: Glycolysis
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•
•
•
•
Breaks (C6) glucose into 2 pyruvate (C3)
Breaks C-C bond
Forms 2 NADH (high energy)
Forms a net of 2 ATP per glucose
Takes place in cytoplasm
Must have 2 NAD+ as reactants to run
Does not release CO2 or need Oxygen
glucose
GLYCOLYSIS
pyruvate
animal cell (eukaryotic)
All cells use Glycolysis
even bacteria
plant cell (eukaryotic)
bacterial cell (prokaryotic)
Glycolysis:
2 ATP in for
“Priming”
4 ATP out
Net: 2 ATP
ATP formation by phosphate transfer
P group transferred
onto now a ATP
Fuel
Molecule
with 2 P
Now Fuel
Molecule
with 1 P
Energy tab so far: 1 Glucose:
• Glycolysis net:
2 ATP
3 Steps to Cellular respiration
From the cytoplasm to the mitochondria
• Pyruvate moves into the mitochondrion
• Some preparatory steps from 2 NADH
(a cofactor)
• Form here the products go to the Krebs
Cycle
The Krebs Cycle
• Takes place in the inner most
compartment of the mitochondria
• Breaks all C-C bonds, uses up all the
remainders of glucose
• Releases CO2 Carbon dioxide that you
breath out
• Loads cofactors NADH, FADH2
• Forms 2 ATP
Krebs Cycle
Energy tab so far: 1 Glucose:
• Glycolysis net:
• Krebs Cycle:
2 ATP
2 ATP
3 Steps to Cellular respiration
Electron Transport Chain
• Electron flow along inner membrane
• All cofactors (coenzymes) from Glycolysis,
preparatory steps and Krebs go to inner
membrane
• Cofactors release electrons, and protons
• Electrons flow and pump protons out creating
gradient
• ATP made n by chemiosmosis
• Electrons flow to Oxygen, the final electron
acceptor, and with protons form water
Mitochondrion
Structure
inner compartment
outer compartment
cytoplasm
outer
mitochondrial
membrane
inner
mitochondrial
membrane
Electron transport chain
OUTER COMPARTMENT
INNER COMPARTMENT
Cofactors (NADH, FADH2) provide protons
and fuel transport chain proton pump
Chemiosmosis by the proton gradient
makes ATP from ADP + Pi
Energy tab so far: 1 Glucose:
• Glycolysis net:
2 ATP
• Krebs Cycle:
2 ATP
• Chemiosmosis: (Electron transport
chains):
32-34 ATP
----------------Grand Total
34-36 ATP
Why we breath:
• We need Oxygen to accept electrons
and keep the transport chain flowing
• We must get rid of the excess carbon
dioxide from the Krebs cycle, or our
blood pH will drop too low.
We need Oxygen to:
Foods other than glucose…
• Catabolism: all biomolecules are broken
down and feed into the pathway at
different points.
– Lipids
– Complex carbohydrates
– Proteins
– Nucleic Acids
All food feeds into Respiration:
Not all cells do aerobic respiration:
• Some live with out oxygen (anaerobes)
• Some need more energy faster than the
Krebs cycle can keep up (muscles under
workout stress)
• Some environments turn off the Krebs cycle
(yeasts)
• Bacteria do not have mitochondria
These cells do Fermentation
start (Glycolysis) in
cytoplasm
start (Glycolysis) in
cytoplasm
completed in mitochondrion
completed in cytoplasm
Aerobic Respiration
In Mitochondria
Anaerobic EnergyFermentation
Mitochondria require oxygen
Fermentation does not
Fermentation equations:
Fermentation
• Normal Glycolysis, only 2 ATP
• No Krebs Cycle
• Must regenerate NAD+ or Glycolysis will
stop
• “wastes” pyruvate energy to reform
NAD+
• Produces either Lactic Acid (Muscles) or
Ethanol and Carbon Dioxide (Yeasts).
• NO additional ATP
Energy Comparison:
Fermentation
Aerobic Respiration
• Glycolysis 2 ATP
• Glycolysis 2 ATP
• Krebs Cycle 2 ATP
• ETC
32-34 ATP
Total
Total
2 ATP
26-38 ATP
Ethanol & Carbon Dioxide Production
The carbon dioxide makes the bubbles in beer
and champagne!! They let it escape in wine
Ethanol & Carbon Dioxide Fermentation
The ethanol bakes away, it is part of
the aroma of baking bread!!
Lactic Acid Production