Cellular Respiration

Energy Is the ability to do work

How do nonliving things get energy? Some energy comes from running water, wind, or the sun Most of our energy comes from burning fuels (oil, gas, coal) This releases energy in the form of heat and light

Living organisms also require energy just like machines Flying bird Beaver building a dam Worm burrowing through soil Making complex compounds from simpler ones (synthesis) Transferring some molecules across the cell membrane (active transport)

How do organisms obtain this energy? Organisms rely on chemical energy stored in their food (mostly carbohydrates) Cellular Respiration is the process by which the energy stored in food inside the cells is released Respiration ≠ breathing

ATP Adenosine triphosphate When the 3rd phosphate is removed and bonded to another compound, energy is released When the 3rd phosphate is removed, the remaining molecule is called adenosine diphosphate (ADP)

Glucose A simple sugar (building blocks of carbohydrates) A single molecule can produce 36 molecules of ATP from ADP

Where does respiration occur? In cells In mitochondria (“powerhouse”, mighty)

Types of Respiration Aerobic: with oxygen Anaerobic: without oxygen

Do Now: What is the difference between aerobic and anaerobic respiration?

Aerobic Respiration Step One Glycolysis: process of breaking down the glucose molecule into 2 3-carbon pyruvic acid molecules

Occurs in cytoplasm of cells

Aerobic Respiration Step Two Pyruvic acid breaks down into carbon dioxide, NADH, and a 2-carbon compound known as an acetyl group Acetyl group combines with coenzyme A to form acetyl CoA

Aerobic Respiration Step Three Krebs Cycle Series of chemical reactions Each turn requires 1 acetyl CoA Each turn produces 2 molecules of carbon dioxide and 4 pairs of hydrogen atoms Each turn produces 1 ATP

Aerobic Respiration Step Four Electron Transport Chain Electrons from hydrogen atoms are passed along from compound to compound At various places on the chain, electrons give up some energy and molecules of ATP are formed

Net Reaction of Aerobic Respiration C6H12O6 + 6O2 6CO2 + 6H2O + 36 ATP

Anaerobic Respiration Step One glycolysis Step Two fermentation

2 types of fermentation Lactic Acid Fermentation Lactic acid builds up in muscles and causes soreness

Muscle Fatigue During periods of prolonged physical activity, muscle cells may use oxygen faster than the circulatory system can supply it Krebs cycle and electron transport chain stop and lactic acid builds up

Alcohol Fermentation

Proteins and fats can also feed into the process at various places

Carbon Dioxide