Cellular Respiration

Cellular Respiration The process by which the mitochondria breaks down glucose to produce ATP is called cellular respiration. C6H12O6 + 6O2  6CO2 + 6H2O + Energy

How much energy is actually present in food? Cellular Respiration How much energy is actually present in food? 1 gram of sugar glucose, when burned in the presence of oxygen, releases 3811 calories of heat energy!

“C” or Calorie used on food labels = 1000 calories (kilocalorie) Cellular Respiration calorie- the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. “C” or Calorie used on food labels = 1000 calories (kilocalorie)

Cellular Respiration Cells release the energy from glucose and other food components (they don’t burn it)

Cellular Respiration When the body has oxygen, aerobic respiration can take place and produce 36 ATP molecules. There are 3 stages of aerobic respiration: Glycolysis Krebs cycle (aka Citric Acid Cycle) Electron transport chain

THE BIG PICTURE

Glycolysis Glycolysis takes place in the cytoplasm of the cell.

Glycolysis Glycolysis is the process where glucose is broken down in 2 pyruvic acid molecules. Pyruvic acid is a 3 carbon molecule. The net gain of ATP molecules in glycolysis is 2 ATP molecules. 4 -2 2

Glycolysis Following glycolysis, the pyruvic acid moves into the mitochondria.

The Krebs Cycle Citric Acid Cycle AKA Citric Acid Cycle The Krebs cycle takes place in the MATRIX! Pyruvic acid enters the Krebs cycle and becomes broken down. As this occurs, 2 carbon dioxide molecules are released. In addition, 2 ATP molecules are released. Electron carriers such as FAD and NAD are used to pick up energized electrons and pass them to the ETC.

The Krebs Cycle AKA Citric Acid Cycle

Krebs Cycle 2 ATP NADH + H pyruvic acid FADH2 ADP NAD CO2 FAD Electron carriers NAD NADH + H pyruvic acid FAD FADH2 CO2 FYI: Flavin adenine dinucleotide Nicotinamide adenine dinucleotide

The Electron Transport Chain The last step of respiration is the electron transport chain or ETC. It takes place in the inner membrane. In the presence of oxygen, the electron transport chain will produce 32 ATP molecules and water. The total of ATP molecules released from AEROBIC respiration is 36. 36 36 36 36

Electron Transport Chain Electron carriers NADH and FADH2 release the Hydrogen ions across the membrane. This creates a concentration gradient. When oxygen enters the ETC, it becomes the final electron acceptor of the Hydrogens and creates H2O. As the hydrogen ions come back across the membrane, ADP is converted into ATP. Animation: http://www.science.smith.edu/departments/Biology/Bio231/etc.html http://vcell.ndsu.nodak.edu/animations/etc/movie.htm http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter9/animations.html#

Electron Transport Chain Electron carriers NADH and FADH release the Hydrogen ions to proteins to cross the membrane. This creates a concentration gradient. When oxygen enters the ETC, it becomes the final electron acceptor of the Hydrogen ions and creates H2O. As the hydrogen ions come back across the membrane, ADP is converted into ATP.

THE BIG PICTURE

Cellular respiration

Anaerobic Resp Fermentation AKA Fermentation There are times when cells are without oxygen for a short period of time. When this happens, anaerobic respiration is taking place. In anaerobic respiration, glycolysis takes place; then followed by one of two pathways: Lactic Acid Fermentation or Alcoholic Fermentation. Total ATP molecules released = 2.

Aerobic: presence of oxygen Anaerobic: absence of oxygen respiration Aerobic

Types of Anaerobic Respiration When our cells run out of oxygen and begin fermentation, we build up lactic acid. That lactic acid build up in the muscle makes us feel a cramp and burning sensation. C6H12O6  ATP + lactic acid Lactic Acid Fermentation

fermentation

Types of Anaerobic Respiration Some fungi also undergo fermentation. They release ethyl alcohol and carbon dioxide. C6H12O6  ATP + CO2 + ethyl alcohol This process is key for the yeast that create wine and other alcoholic beverages. Alcoholic Fermentation

Types of Anaerobic Respiration Yeast undergo this type of fermentation when making bread.

fermentation

Comparing Photosynthesis and Respiration Glucose made Light energy required ATP broken down in 2nd phase of p.s. CO2 taken in O2 released Needs water Takes place in chloroplast Takes place in autotrophs Glucose broken down Light is not required Energy created in ATP CO2 released O2 taken in Water released Takes place in mitochondria Takes place in all organisms Require use of ATP molecules Take place in plants Necessary to sustain all life on earth