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Cellular Respiration. Ms. Napolitano & Mrs. Haas CP Biology. Recall:. The photosynthesis equation is 6CO 2 + 6H 2 O + light 6O 2 + C 6 H 12 O 6. Food. Food – source of raw material for the cells of the body Energy source
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Cellular Respiration Ms. Napolitano & Mrs. Haas CP Biology
Recall: • The photosynthesis equation is 6CO2 + 6H2O + light 6O2 + C6H12O6
Food • Food – source of raw material for the cells of the body • Energy source • calorie – amount of energy needed to raise 1 gram of water 1 degree Celsius • Calorie = kilocalorie = 1000 calories
Cellular Respiration • Cellular respiration – the process that releases energy by breaking down glucose & other food molecules in the presence of oxygen • The equation for cellular respiration is: 6O2 + C6H12O6 6CO2 + 6H2O + Energy
3 Parts of Cellular Respiration: • Glycolysis • Cytoplasm • Krebs cycle (AKA citric acid cycle) • Mitochondrial matrix • Electron transport chain • Inner mitochondrial matrix
PART I Glycolysis
Glycolysis • Glycolysis – process in which one molecule of glucose is broken in half • Produces 2 molecules of pyruvic acid = 3C compound • Anaerobic - does not require O2
ATP & NADPH Production • The cell needs to input some energy before more can be produced • 2 ATP used up, 4 ATP made = 2 ATP net gain • High-energy electrons are carried by NAD+ • Makes NADH • Similar to NADP+ in photosynthesis • Overall glycolysis equation: glucose 2 pyruvic acid + 2 ATP + 2 NADH
PART II The Krebs Cycle
The Krebs Cycle • Recall: 2 pyruvic acid molecules were made during glycolysis • Krebs cycle – pyruvic acid is broken down into CO2
Steps of the Krebs Cycle: • 1C from pyruvic acid becomes CO2 • Other 2C’s joined to a coenzyme to make acetyl-CoA • Acetyl group (2C) is converted to citric acid (4C) • 6C compound • Citric acid becomes 4C again • C’s become CO2 • ADP ATP • NAD+ NADH • FAD FADH2 High-energy electron carriers
Final Products of the Krebs Cycle: • 6 NADH • 2 FADH2 • 2 ATP • 2 CO2
PART III The Electron Transport Chain
The Electron Transport Chain • The electron transport chain – uses high-energy electrons from the Krebs cycle to convert ADP into ATP
Product: H2O • e- are passed from one protein to the next • Enzyme at the end combines e- with H+ and O2 to form H2O
Product: ATP • When 2e- pass through ETC, energy transports H+ across the membrane • ATP synthase pumps H+ to the other side of the membrane via facilitated diffusion • ATP synthase rotates like a turbine, making ADP + P ATP
Totals • Glycolysis = 2 ATP (net) • Krebs cycle + ETC = ~36 ATP • Total = ~38 ATP molecules from 1 glucose molecule!
Fermentation • Fermentation – process by which ATP is made in the absence of O2 • AKA anaerobic • Goes through glycolysis, then picks a different pathway • Alcoholic fermentation • Alcohol & CO2 is made as wastes • Made by yeast - causes bread to rise • Lactic acid fermentation • Lactic acid is made as a waste • Causes muscle soreness or helps make dairy products
Energy & Exercise • Quick energy • Only enough ATP in muscles for ~50m sprint (few seconds) • Lactic acid fermentation – ATP made for ~200-300m sprint (~90s) • Lactic acid removal requires extra O2 • Long-term energy • Cell respiration is the only way to make ATP for the long-term • Pace yourself! • Energy stored in muscles as glycogen • Stored glycogen - ~15-20 min of activity, then other energy forms get broken down (ex. fats – weight control!)