Cellular RespirationCellular Respiration
9-1 – 9-29-1 – 9-2
Chemical Energy and FoodChemical Energy and Food
• All living things consume and use energy– Heterotrophs take in food which is digested
and broken down into C6H12O6
– Autotrophs can’t “eat” so they make C6H12O6 through photosynthesis
– Mitochondria then transform the “food energy” into chemical energy ( )ATP
Chemical Energy and FoodChemical Energy and Food
• Calories– Unit of measurement for energy– Amount of energy needed to raise the
temperature of 1 gram of water 1 degree Celsius
– Nutrition information on food is Calories (1000 calories)
Chemical Energy and FoodChemical Energy and Food
• Calories– 1 gram of glucose (sugar) produces 3811
calories when burned– A lot of energy for a cell– Our bodies use glycolysis and cellular
respiration to gradually release energy in food
Overview of Cellular RespirationOverview of Cellular Respiration
• Mitochondria “make change” energetically
• Take the energy in a sugar and convert it into more conveniently-sized packages
ATP
Overview of Cellular RespirationOverview of Cellular Respiration
• Definition: process that releases energy by breaking down glucose and other food molecules
• Requires oxygen
Overview of Cellular RespirationOverview of Cellular Respiration
C6H12O6 + 6O2 → 6CO2 + 6H2O + energyCarbondioxide
WaterCarbohydrate Oxygen ATP
Overview of Cellular RespirationOverview of Cellular Respiration
• Step 1: Glycolysis
• Step 2: Krebs cycle
• Step 3: Electron transport chain
Overview of Cellular RespirationOverview of Cellular Respiration
MATRIX:Breakdown ofpyruvic acid, Krebs cycle
Outer membrane
INNER MEMBRANE:Electron transportchain
CYTOPLASM:Glycolysis
MITOCHONDRION
Step 1: GlycolysisStep 1: Glycolysis
• Occurs in cytoplasm of ALL cells
• Does not require oxygen
• Process of splitting a glucose (C6H12O6) molecule in half
Step 1: GlycolysisStep 1: Glycolysis
• Products:– 2 pyruvic acid molecules
• What you get when you split glucose in half• Used in Krebs cycle
– Energized electrons• Carried to the electron transport chain (ETC) by
• Used to generate
NADH
ATP
Step 1: GlycolysisStep 1: Glycolysis
• Products:– 2
• Uses up 2 ATP• Produces 4 ATP
– Net yield = 2
ATP
ATP
Step 1: GlycolysisStep 1: Glycolysis
1 GlucoseC6H12O6
Step 1: GlycolysisStep 1: Glycolysis
1 GlucoseC6H12O6
2 ADPATP2
Step 1: GlycolysisStep 1: Glycolysis
1 GlucoseC6H12O6
2 ADP
P
P
2 PGAL
ATP2
Step 1: GlycolysisStep 1: Glycolysis
1 GlucoseC6H12O6
2 ADP
P
P
2 PGAL
4ADP + 4 Pi
2 NAD+ 2 NADH
4ATPATP2
To ETC
Step 1: GlycolysisStep 1: Glycolysis
1 GlucoseC6H12O6
2 ADP
P
P
2 PGAL
4ADP + 4 Pi
2 NAD+
4ATP
2 Pyruvicacid
ATP2
2 NADH
To ETC
Step 1: GlycolysisStep 1: Glycolysis
• If oxygen is present pyruvic acid molecules enter the mitochondria for the Krebs cycle– Leads to production of lots of
• If oxygen is absent pyruvic acid molecules stay in the cytoplasm for fermentation– No more ATP is produced
ATP
Cellular RespirationCellular Respiration
C6H12O6 + 6O2 → 6CO2 + 6H2O + energyCarbondioxide
WaterCarbohydrate Oxygen ATP
Cellular RespirationCellular Respiration
Step 1: Glycolysis
• Step 2: Krebs cycle
• Step 3: Electron transport chain
Step 2: Krebs CycleStep 2: Krebs Cycle
• Requires oxygen– If there is no oxygen present pyruvic acid
stays in the cytoplasm and does fermentation
Step 2: Krebs CycleStep 2: Krebs Cycle
• Involves first breaking down pyruvic acid formed during glycolysis
• Occurs as pyruvic acid crosses the mitochondrial membrane
• Rest of the cycle occurs in the mitochondrial matrix
Step 2: Krebs CycleStep 2: Krebs Cycle
• Products:– 3 CO2
• Exhaled
– 2– Lots more energized electrons
• Carried to ETC by and• Used to generate more
ATP
NADH FADH2
ATP
Step 2: Krebs Cycle – Break Step 2: Krebs Cycle – Break Down of Pyruvic AcidDown of Pyruvic Acid
CYTOPLASM Mitochondrialmembrane
MITOCHONDRION
Pyruvicacid
(from glycolysis)CO2
NAD+ NADH
Co-A
Co-A
Acetyl Co-A
TOKREBSCYCLE
3 carbons
Exhaled
To ETC
4 carboncompound
Co-ACo-A
CitricAcid
CO2
NAD+
NADH
5-carboncompound
CO2NAD+
NADH
ADP
ATP
NAD+
NADH
FAD
FADH2
KREBSCYCLE
Cellular RespirationCellular Respiration
C6H12O6 + 6O2 → 6CO2 + 6H2O + energyCarbondioxide
WaterCarbohydrate Oxygen ATP
Cellular RespirationCellular Respiration
Step 1: GlycolysisStep 2: Krebs cycle
• Step 3: Electron transport chain
Cellular RespirationCellular Respiration
Mitochondrialmatrix
Outer membrane
Inner membrane
CYTOPLASM
MITOCHONDRION
Intermembranespace
Step 3: Electron Transport ChainStep 3: Electron Transport Chain
• Happens on inner membrane of mitochondria
• Major production of
• Uses energized electrons delivered by and created during glycolysis and the Krebs cycle
NADH
FADH2
ATP
Step 3: Electron Transport ChainStep 3: Electron Transport Chain
• Energized electrons are passed along a series of molecules embedded in the inner mitochondrial membrane
• ETC molecules take the electrons’ energy
• Uses energy to make ATP
Step 3: Electron Transport ChainStep 3: Electron Transport ChainCYTOPLASM
OUTERMEMBRANE
INNERMEMBRANE
ELECTRON TRANSPORT CHAIN
MITOCHONDRIALMATRIX
INTERMEMBRANE
SPACE
Step 3: Electron Transport ChainStep 3: Electron Transport Chain
• Oxygen is the final electron acceptor– If oxygen is not present electrons stop flowing
through ETC– ATP production stops – Combines with H+ ions to form water
Step 3: Electron Transport ChainStep 3: Electron Transport ChainCYTOPLASM
OUTERMEMBRANE
INNERMEMBRANE
ELECTRON TRANSPORT CHAIN
MITOCHONDRIALMATRIX
INTERMEMBRANE
SPACE
Cellular RespirationCellular Respiration
C6H12O6 + 6O2 → 6CO2 + 6H2O + energyCarbondioxide
WaterCarbohydrate Oxygen ATP
Overall ATP ProductionOverall ATP Production
Glycolysis produces 2 ATP
Krebs cycle produces 2
Electron transport chainproduces **32
ATP
ATP
**Makes ATP from electrons carried to it from the first 3 steps
FOR EVERY GLUCOSE MOLECULE:
Overall ATP ProductionOverall ATP Production
Overall,cellularrespirationmakes
ATP36
FermentationFermentation
• Occurs when there is no oxygen available
FermentationFermentation
• Pyruvic acid molecules are still formed through glycolysis
• Occurs in the cytoplasm– Mitochondria are not involved
• Pyruvic acid is broken down differently:– No ATP is produced after glycolysis
FermentationFermentation
• 2 types:– Alcoholic fermentation– Lactic acid fermentation
Alcoholic FermentationAlcoholic Fermentation
• Ethyl alcohol and CO2 are byproducts
• Occurs in organisms that live in environments lacking oxygen
Alcoholic FermentationAlcoholic Fermentation
Glycolysis
2 Ethanol
2 CO2
Alcoholic FermentationAlcoholic Fermentation
• Example: yeast– When spores are placed in a food-rich,
oxygen-free environment the organisms come to life
– Begin doing alcoholic fermentation
– CO2 produced makes bread rise
– Tiny amounts of alcohol produced evaporate as bread bakes
Lactic Acid FermentationLactic Acid Fermentation
• Performed by cells when they run out of oxygen
• After glycolysis pyruvic acid is transformed into lactic acid
• Causes burning sensation in muscles
Lactic Acid FermentationLactic Acid Fermentation
Glycolysis
Glucose
Pyruvic acid
Lactic acid
Energy and ExerciseEnergy and Exercise
• Muscle cells use tremendous amounts of ATP to contract and create movement
• Cells keep a small amount of ATP on hand– Enough for only a few seconds of intense
exercise
• After that ATP is produced by lactic acid fermentation
Energy and ExerciseEnergy and Exercise
• Lactic acid fermentation can provide ATP for about 90 seconds of intense exercise
• Lactic acid is produced by a series of reactions that require extra oxygen– Reason for breathing heavily at the end of a
longer race
Energy and ExerciseEnergy and Exercise
• Cellular respiration is the only way to generate ATP after 90 seconds– Slow process– Why a marathon and a sprint look differently
Energy and ExerciseEnergy and Exercise
• Cellular respiration is the only way to generate ATP after 90 seconds– Slow process– Why a marathon and a sprint look differently– Training allows a person to exercise more
vigorously beyond the 90 second barrier
Energy and ExerciseEnergy and Exercise
• Fuel for making ATP is stored as glycogen– Carbohydrate– Body contains enough glycogen to fuel
cellular respiration for 15-20 minutes– Body burns fat after that