Objectives 9.1 Cellular Respiration -Explain where organisms get the energy they need for life processes. -Define cellular respiration. -Compare photosynthesis and cellular respiration.

Chemical Energy and Food Food molecules contain chemical energy that is released when its chemical bonds are broken during a process called CELLULAR RESPIRATION.

What is a Calorie? Energy stored in food is expressed in units called calories. A Calorie is the amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius.

Overview of Cellular Respiration If oxygen is available, organisms can obtain energy from food by a process called cellular respiration. Equation: 6 O2 + C6H12O6  6 CO2 + 6 H2O + Energy In words: Oxygen + Glucose  Carbon dioxide + Water + Energy

Stages of Cellular Respiration The three main stages of cellular respiration are: 1. Glycolysis 2. Krebs cycle 3. The electron transport chain

Stage 1: Glycolysis Glycolysis is anaerobic and produces only a small amount of energy. *2 ATP molecules*

Stage 2: Krebs Cycle *2 ATP molecules* During the Krebs cycle, a little more energy is generated using pyruvic acid to power the Electron Transport Chain. *2 ATP molecules*

Stage 3: The Electron Transport Chain The electron transport chain produces the bulk of the energy in cellular respiration by using oxygen. *32 net ATP molecules*

Aerobic vs Anaerobic Aerobic = with oxygen Anaerobic = without oxygen

Photosynthesis and Cellular Respiration Photosynthesis and cellular respiration are opposite processes. The energy flows in opposite directions.

True or False Either cellular respiration or fermentation can be used to release energy, depending on the presence of carbohydrates. _________________________ The Krebs cycle releases energy in the form of ATP. _________________________ Electron carriers bring electrons from glycolysis and the Krebs cycle to the electron transport chain. _________________________ Without the Krebs cycle, the electron transport chain cannot function. _________________________

ANSWERS Either cellular respiration or fermentation can be used to release energy, depending on the presence of carbohydrates. False, oxygen The Krebs cycle releases energy in the form of ATP. True Electron carriers bring electrons from glycolysis and the Krebs cycle to the electron transport chain.True Without the Krebs cycle, the electron transport chain cannot function. True