Transcript Cell Respiration

Cellular Respiration
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process where cells break down sugars to produce ATP
both autotrophs and heterotrophs use
make CO2 and water from sugar and O2
Occurs in the mitochondria
Products of cellular respiration are the reactants of photosynthesis
Products of photosynthesis are the reactants in cellular respiration
• Two stages
1. Glycolysis
2. Aerobic respiration
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Photosynthesis-Cellular Respiration Cycle
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Cellular Respiration
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Glycolysis
• takes place in the cytosol of cells (cytoplasm)
• does not need Oxygen present (anaerobic)
• Step 1
• 1 six-carbon glucose molecule is split to form 2
three-carbon pyruvic acid molecules
• 2 ATP molecules are used
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Glycolysis
• takes place in the cytosol of cells (cytoplasm)
• does not need Oxygen present (anaerobic)
• Step 2
• Electrons from the pyruvic acid molecules join NAD+
to form NADH
• Pyruvic acid molecules become Pyruvate
• 4 ATP are made
• A net yield of 2 ATP molecules is produced
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Glycolysis
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Glycolysis
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Efficiency of Glycolysis
• not very efficient at transferring energy from glucose
to ATP
• only about 2% of the energy available from the
oxidation of glucose is captured as ATP
• energy originally contained in glucose is still held in
pyruvic acid
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Aerobic Respiration
• occurs in the mitochondria
• only occurs if oxygen is present in the cell
• Two stages
1. Krebs Cycle
• occurs in the mitochondrial matrix
2. Electron Transport Chain (which is associated
with chemiosmosis)
• located in the inner membrane
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Krebs Cycle
• Step 1
• Pyruvate splits into a two carbon molecule and CO2
• Electrons join NAD+ to make NADH
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Krebs Cycle
• Step 2
• Pyruvic acid (2 carbon molecule) reacts with coenzyme A to
form acetyl CoA
• Acetyl CoA enters the Krebs cycle
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Krebs Cycle
• Step 3
• CoA joins with a four carbon molecule to make Citric acid (a
six carbon molecule)
• Coenzyme A goes back to step 2
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Krebs Cycle
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Step 4
Citric acid is broken down and makes a five carbon molecule
NADH is made
CO2 is made
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Krebs Cycle
• Step 5
• The five carbon molecule is broken down to make a four
carbon molecule
• NADH is made
• CO2 is made
• 1 ATP is made
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Krebs Cycle
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Step 6
Enzymes rearrange the four carbon molecule
Electrons are released
NADH is made
• Products from one glucose molecule:
– 6 CO2, 2 ATP, 8 NADH, 2 FADH2
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Krebs Cycle
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Electron Transport Chain & Chemiosmosis
Step 1
• Electrons are removed from NADH and FADH2
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Electron Transport Chain & Chemiosmosis
Step 2
• Electrons are passed from molecule to molecule in the ETC
• Hydrogen ions are pumped across the membrane
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Electron Transport Chain & Chemiosmosis
Step 3
• Hydrogen ions diffuse through a protein channel
• ATP synthase adds phosphates to ADP to Make ATP
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Electron Transport Chain & Chemiosmosis
Step 4
• Oxygen combines with electrons and Hydrogen ions to form water
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Efficiency of Cellular Respiration
• produce up to 38 ATP molecules from a single
molecule of glucose
• 2 from glycolysis, 2 from Krebs, 34 from ETC
• Cellular respiration is 20 times more efficient than
glycolysis alone
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Summary of Cellular Respiration
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Comparing Aerobic and Anaerobic Respiration
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Cellular Respiration Versus Fermentation
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