Cellular Respiration is a metabolic pathway not a

• Cellular Respiration is a metabolic pathway, not a single reaction • Many chemical reactions, both aerobic and anaerobic, are involved in the process of cellular respiration • Lots of enzymes are required for the process to occur 1

The Relationship Between Cellular Respiration and Breathing • Cellular respiration and breathing are closely related • Cellular respiration requires a cell to exchange gases with its surroundings • Breathing exchanges these gases between the blood and outside air 2

Breathing Lungs Muscle cells Cellular Respiration 3

The Role of Oxygen in Cellular Respiration • During cellular respiration, hydrogen and its bonding electrons change partners • Hydrogen and its electrons go from sugar to oxygen, forming water 4

The Metabolic Pathway of Cellular Respiration • Cellular respiration is an example of a metabolic pathway • A series of chemical reactions in cells either building or breaking down molecules 5

The Metabolic Pathway of Cellular Respiration All of the reactions involved in cellular respiration can be grouped into three main stages • Glycolysis – occurs in cytoplasm • The Krebs cycle – occurs in matrix of mitochondria • Electron transport – occurs across the mitochondrial membrane 6

FERMENTATION: ANAEROBIC HARVEST OF FOOD ENERGY Some of your cells can actually work for short periods without oxygen (anaerobic respiration) For example, muscle cells can produce ATP under anaerobic conditions Called Fermentation Involves The anaerobic harvest of food energy 7

Fermentation in Human Muscle Cells • Human muscle cells can make ATP with and without oxygen • They have enough ATP to support activities such as quick sprinting for about 5 seconds • A secondary supply of energy (creatine phosphate) can keep muscle cells going for another 10 seconds • To keep running, your muscles must generate ATP by the anaerobic process of fermentation 8

Fermentation in Microorganisms • Various types of microorganisms perform fermentation • Yeast cells carry out a slightly different type of fermentation pathway • This pathway produces CO 2 and ethyl alcohol

The food industry uses yeast to produce various food products 10