Cellular Respiration Chapter 9 Section 1 & 2

Food serves as the source of energy for cells. A Calorie – is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. Cells don’t burn glucose & other food compounds, they gradually release the energy.

Cellular Respiration The process that releases energy by breaking down glucose & other food molecules in the presence of oxygen. 6O 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O + Energy oxygen + glucose carbon dioxide + water + energy **draw fig. 9-2 on pg. 222 for your notes

3 Stages make up Cellular Respiration Gycolysis Kreb Cycle Electron Transport

3 Stages make up Cellular Respiration Glycolysis – process in which 1 molecule of glucose is broken in half, producing 2 molecules of pyruvic acid & gains 2 ATP molecules. O 2 present - it is followed by the Kreb Cycle & the electron transport chain. O 2 not present (anaerobic) - it is followed by fermentation. Fermentation – releases energy in food & converts NADH back into NAD+ keeping the supply of ATP constant.

Fermentation Alcoholic fermentation – yeasts & a few other microorganisms; causes bread dough to rise. Lactic Acid fermentation – in muscles during rapid exercise when the body can’t supply enough O 2 to the tissues; without oxygen, the body isn’t able to produce the ATP required. Buildup causes pain & soreness.

3 Stages make up Cellular Respiration Kreb Cycle – requires O 2 (aerobic) In eukaryotes. Takes place in the mitochondria. Aka. Citric acid cycle b/c it’s one of the first products. Pyruvic acid is broken down into CO 2 which is released into the air. NAD+ is changed to NADH & FAD is changed to FADH 2 which carry high-energy electrons to the electron transport chain.

3 Stages make up Cellular Respiration Electron Transport – uses high-energy electrons from the Krebs cycle to convert ADP into ATP. In eukaryotes it’s composed of carrier proteins located in the mitochondria. In prokaryotes the same chain is in the cell membrane where energy is used to move H+ ions through ATP synthase. ATP synthase – protein sphere that spins, adding a phosphate to ADP creating ATP. No O 2 – product is glycolysis. Yes O 2 – more ATP is extracted.

Cellular Respiration Glycolysis + Krebs + Electron Transport = 36 ATP / glucose molecules.

The Human Body Contains small amounts of ATP. When the body needs energy fast, muscle cells produce ATP by Lactic Acid Fermentation. For long-term needs, the body must use cellular respiration.

Comparing Photosynthesis & Cellular Respiration Energy flows in Photosynthesis Cellular Respiration takes place in the opposite direction. Photosynthesis – removes CO 2 & puts O 2 back into air. Cellular Respiration – removes O 2 & puts CO 2 back into air. **copy chart in fig on pg. 232.