photosynthesis and cellular respirationsection 3 ch7: cellular respiration pg 131
TRANSCRIPT
Photosynthesis and Cellular Respiration Section 3
CH7: Cellular Respiration pg 131
Photosynthesis and Cellular Respiration Section 3
Glycolysis
• The primary fuel for cellular respiration is glucose.
Equation for Photosynthesis• 6CO2 + 6H2O + pigment + sunlight C6H12O6 + 6O2
Equation for Cellular Respiration
• C6H12O6 + O2 CO2 + H2O + ENERGY (ATP)
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Glycolysis, continued
• In glycolysis, enzymes break down one six-carbon molecule of glucose into two three-carbon pyruvate molecules.
• The breaking of a sugar molecule by glycolysis results in a net gain of two ATP molecules.
• This process of glycolysis is anaerobic, or takes place without oxygen in the cytoplasm.
Photosynthesis and Cellular Respiration Section 3
Glycolysis, continued• Glycolysis is the only source of energy for some
prokaryotes.
• Other organisms use oxygen to release even more energy from a glucose molecule. – Metabolic processes that require oxygen are aerobic.
Photosynthesis and Cellular Respiration Section 3
Glycolysis, continued
• Step 1, Breaking Down Glucose– Two ATP molecules are used to break glucose into
two smaller units.
– Phosphate is attached to these 2 – three carbon sugars (G3P)
Photosynthesis and Cellular Respiration Section 3
• Step 2, NADH Production– Each of the three carbon sugars (G3P) react with
another phosphate (not ATP)
– Hydrogen atoms from these compounds transfer to two molecules of NAD+ resulting in 2 NADH molecules (Hydrogen ion/proton and e- carrier)
Glycolysis, continued
Photosynthesis and Cellular Respiration Section 3
Glycolysis, continued
• Step 3, Pyruvate Production– In a series of 4 reactions, each of the 3 – carbon
sugars are converted into a 3 – carbon molecule of pyruvate, resulting in 4 ATP molecules.
• BUT 2 ATP molecules were used in step one, so net total for glycolysis is 2 ATP molecules
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Glycolysis
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Fermentation
• To make ATP during glycolysis, NAD+ is converted to NADH. – Organisms must recycle NAD+ to continue making ATP through
glycolysis.
• The process in which carbohydrates are broken down in the absence of oxygen is called fermentation.– Allowing glycolysis to continue supplying a cell with ATP in
anaerobic conditions.
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Pathway Reaction
Lactic Acid Fermentation
PYRUVIC ACID + NADH LACTIC ACID + NAD+ *occurs in muscle cells for short term energy production, also used in the production of foods ex. yogurt, Kim chi, sauerkraut
Alcoholic Fermentation
PYRUVIC ACID + NADH ALCOHOL+ CO2 + NAD+ *occurs in yeast cells and is used in the production of beer, wine and bread
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Two Types of Fermentation
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Add this onto your Cellular Respiration illustration
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Aerobic Respiration
• The first stage of aerobic respiration is the Krebs cycle, a series of reactions that produce electron carriers (NADH and FADH2).
• The electron carriers enter an electron transport chain, which powers ATP synthase.
• Up to 38 ATP molecules can be produced from one glucose molecule in aerobic respiration.
Photosynthesis and Cellular Respiration Section 3
Photosynthesis and Cellular Respiration Section 3
Kreb’s Cycle
• Pyruvate (from glycolysis) is broken down and combined with other carbon compounds creating CoA.– Releasing CO2
• The total yield of energy-storing products from the Krebs cycle is 2 ATP, 6 NADH, and 2 FADH2.
Photosynthesis and Cellular Respiration Section 3
Photosynthesis and Cellular Respiration Section 3
Photosynthesis and Cellular Respiration Section 3
Electron Transport Chain
• The second stage of aerobic respiration takes place in the inner membranes of mitochondria– ATP synthase are located here
• Electron carriers (NADH and FADH2), from the Krebs cycle– transfer energy in the form of e- and H+ into the electron
transport chain.– e- are used to pump the H+ across the membrane to create a
concentration gradient
Photosynthesis and Cellular Respiration Section 3
Photosynthesis and Cellular Respiration Section 3
Electron Transport ChainATP Production• Hydrogen ions diffuse through ATP synthase, providing
energy to produce several ATP molecules from ADP.
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• End of the ETC, the e- combine with an oxygen atom and two hydrogen ions to form two water molecules.
• If oxygen is not present, the electron transport chain stops.
• The electron carriers are not recycled, so the Krebs cycle also stops.
The Role of Oxygen
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Efficiency of Cellular Respiration• In the first stage of cellular respiration, glucose is broken
down to pyruvate during glycolysis, an anaerobic process.
• Glycolysis results in 2 ATP molecules for each glucose molecule that is broken down.
• In the 2nd stage, pyruvate EITHER passes through the Krebs cycle OR undergoes fermentation. – Fermentation recycles NAD+ but does not produce ATP.
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Efficiency of Cellular Respiration cont’d• Cells release energy most efficiently when oxygen is
present
• For each glucose molecule that is broken down, as many as 2 ATP molecules are made during the Krebs cycle.
• The Krebs cycle feeds NADH and FADH2 to the ETC, which can produce up to 34 ATP molecules.
Photosynthesis and Cellular Respiration Section 3
SummaryCellular Respiration
Reactants Products Location
Gycolysis Glucose, 2 ATP 2 Pyruvates, 2NADH, 4 (2) ATP
Cytoplasm
Krebs Cycle 2 AcetylCoA (CoA) CO2, 6NADH, 2FADH2 ,2ATP
Matrix of Mitochondria
ETC 6 NADH, 2FADH2,
O2
34 ATP, H2O, 6NAD, 2FAD
Inner Mitochondrial Membrane