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Cellular Respiration
Essential Questions:
How is the energy in our food released?
How does aerobic respiration and anaerobic respiration compare and contrast?
What are the 2 types of anaerobic respiration?
How are the processes of photosynthesis and cell respiration different?
Cellular Respiration
• Cellular Respiration = Process by which mitochondria break down food molecules to produce ATP
• Does not use Oxygen is called Anaerobic
• Does use Oxygen is called Aerobic
• There are 3 stages of Cellular Respiration:
1) Glycolysis (Anaerobic)2) Citric Acid Cycle (Aerobic)3) Electron Transport Chain (Aerobic)
Glycolysis - Anaerobic• Glycolysis = series of chemical
reactions in the cytoplasm of a cell that break down glucose (a 6 Carbon compound) into 2 molecules of pyruvic acid (a 3 Carbon compound)
• NAD+ accepts a pair of high energy electrons to pass that energy to other pathways in the cell.
• 2 Molecules of ATP are used to start Glycolysis and only 4 ATPs are produced
• Net only 2 ATP• Then pyruvic acid proceeds to the
Mitochondria to begin the Citric Acid Cycle and the Electron Transport Chain (in the presence of Oxygen)
Anaerobic Processes • Sometimes your cells are without
Oxygen for short periods of time (during strenuous exercise, etc)
• In order to make ATP, the process of Fermentation occurs after Glycolysis until Oxygen becomes available again.
• During fermentation, cells convert NADH to NAD+ by passing high energy electrons back to pyruvic acid. This action converts NADH back into the electron carrier NAD+ allowing glycolysis to continue producing a steady supply of ATP.
• Some organisms simply live in areas without Oxygen and must produce their ATP this way.
• http://www.youtube.com/watch?v=y_k8xLrBUfg
2 Anaerobic Processes:Lactic Acid Fermentation & Alcoholic Fermentation
• Without Oxygen, the Electron Transport Chain becomes backed up since no Oxygen is there to be the final electron acceptor
• Pyruvic Acid + NADH → lactic acid + NAD+• Lactic Acid is the cause of
sore muscles.
• Certain organisms living in anaerobic environments will rely on this type of ATP synthesis.
• Pyruvic acid + NADH →
alcohol + CO2 + NAD+
• Yeast use this type of fermentation to create C02 and ethyl alcohol.
Aerobic Respiration
• Most efficient type of Cellular Respiration!
• Requires Oxygen• Occurs in 3 steps:
– 1) Glycolysis– 2) Citric Acid Cycle– 3) Electron Transport Chain
• Glycolysis is the only step that is Anaerobic.
• The other Anaerobic process was fermentation.
Aerobic Respiration - Mitochondria• Remember, Glycolysis breaks
down 1 glucose into 2 pyruvic acid molecules
• Heads to Mitochondria for Aerobic Respiration
• Citric Acid Cycle occurs in the outer mitochondrial membrane
• Calvin Cycle – glucose was formed
• Citric Acid Cycle – glucose is being broken down
• For 1 Glucose molecule, 1 ATP is made for every turn of the cycle.
• http://www.wiley.com/college/pratt/0471393878/student/animations/citric_acid_cycle/index.html
Electron Transport Chain 1:2• Very Similar to the ETC of the
thylakoid in plants!• NADH and FADH2 pas
energized electrons from protein to protein releasing small amounts of energy.
• A Concentration gradient forms in the mitochondria – Hydrogen ions inside– Lack of Hydrogen ions
outside• An Electrical gradient forms in
the mitochondria (H+ ions pumped inside)– Positive in the center– Negative on the outside
Electron Transport Chain 2:2
• The final electron acceptor is Oxygen
• Yields Carbon Dioxide (CO2), 2 Water, and 36 ATP
• Most efficient process since anaerobic respiration only yields 2 ATP. • http://www2.nl.edu/jste/electron_transport_system.htm
What type of protein am I?
An Enzyme!
Overview of Cellular RespirationLabel the picture on your notes!
Comparing Photosynthesis & Respiration
• PHOTOSYNTHESIS– Food accumulated– Energy from the Sun
stored in Glucose
– CO2 taken in
– Oxygen given off– Produces Glucose from
PGAL– Goes on only in Light– Occurs in the presence
of Chlorophyll of Plants only
– Chloroplasts
• RESPIRATION– Food Broken Down– Energy of Glucose
Released
– CO2 given off
– Oxygen taken in– Produces Carbon Dioxide,
Water & ATP– Goes on Day & Night– Occurs in all Living Cells
(Plants and Animals)– Mitochondria