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Cellular Cellular RespirationRespiration
-the breaking down of food molecules in the presence of oxygen to release energyCC66HH1212OO66 + O + O22 COCO22 + H + H22OO
ATP++(glucose)
(energy)
Metabolism
• The set of chemical reactions in an organism’s cells that converts food into energy (ATP)
• “Burning calories” refers to how efficiently cells can perform cellular respiration
• More exercise = more energy required = more food required = faster metabolic rate
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What is ATP?
• Molecule that is used as an energy source in the cell
• Produced in mitochondria
• Food molecules are needed to make ATP
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3 Steps of Cellular Respiration (each produces some ATP)
1) Glycolysis - splitting of glucose (2 ATP)
(anaerobic - no O2 needed)2) Citric Acid (Kreb’s) cycle (2 ATP)
(aerobic - O2 needed)3) Electron transport chain (32-34 ATP) (aerobic)
*steps 2 and 3 happen in mitochondria*step 1 happens in the cytoplasm outside the mitochondria
What happens without oxygen?
• Citric acid cycle and electron transport chain (ETC) cannot occur
• Glycolysis is followed by fermentation
• There are two types of fermentation: alcoholic and lactic acid
See diagram
Alcoholic Fermentation
• Happens in microorganisms (yeast and bacteria) in the absence of oxygen (anaerobic)
• Alcohol and CO2 are produced
• Does not produce ATP, but it does allow glycolysis to occur again and again
• Used in the beer and wine industry
Lactic Acid Fermentation
• Happens in muscle tissue of humans and other animals in the absence of oxygen (anaerobic)
• Lactic acid and CO2 are produced
• Does not produce ATP, but it does allow glycolysis to occur again and again
• Produces burning feeling during exercise
When oxygen is present…
• Kreb’s cycle (citric acid cycle) and electron transport chain occur
• Both happen inside the mitochondria
• 2 ATP come from the Kreb’s cycle
• 32-34 ATP come from the electron transport chain
• Total of 36-38 ATP from cellular respiration
(includes 2 ATP from glycolysis)
* ATP amounts shown are produced from ONE glucose molecule
Aerobic vs. Anaerobic
Aerobic Respiration• Energy produced
more slowly• Oxygen needed• Citric acid cycle and
ETC• More ATP are
produced per molecule of glucose
Anaerobic Respiration
• Energy produced quickly
• No oxygen needed
• Glycolysis and fermentation
• Few ATP produced
What is Photosynthesis?
The process of using sunlight to convert CO2 and water into glucose and oxygen
CO2 + H2O C6H12O6 + O2
Reaction takes place in the chloroplast
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Converting Solar Energy
• Plants trap the sun’s energy using a green pigment called chlorophyll
• Chlorophyll is inside the chloroplast
• Solar energy is used to transform CO2 into glucose
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Factors that Affect Photosynthesis
•Water availability•Light intensity (varies from
species to species)•Temperature (extremes
slow down photosynthesis - below 0oC and above 35oC)
The Calvin Cycle
Uses energy stored in ATP to produce glucose from CO2.
* Six CO2 molecules from the atmosphere are needed to produce one glucose molecule
What is the glucose used for?
• Energy source for plant and consumers
• To build starches (stored food source)
• To build new cell walls