What is Cellular Respiration? Once the energy that was in sunlight is changed into chemical energy by photosynthesis, an organism has to transform the chemical energy, glucose, into a a form that can be used by the organism. This process is cellular respiration.

Cellular Respiration Cells break down simple food molecules and release energy. The process by which cells use oxygen to produce energy from food (glucose).

Respiration is in many respects Energy flow & Chemical Cycling in the Biosphere Sunlight energy Ecosystem Photosynthesis (in chloroplasts) Respiration is in many respects the reverse of Photosynthesis Glucose Carbon dioxide Oxygen Water Photosynthesis Build up Cellular respiration (in mitochondria) Respiration Break down for cellular work Figure 6.3 Heat energy

Cellular Respiration Respiration IS NOT Ventilation =breathing Lungs Muscle cells Cellular respiration

EQUATION FOR RESPIRATION CARBON DIOXIDE ATP GLUCOSE C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY OXYGEN WATER

Two Stages of Respiration 1st stage – takes place in cytoplasm Glucose broken down into smaller molecules No O2 is involved Not much energy

Two Stages of Respiration Takes place in mitochondria Small glucose molecules made even smaller Requires O2 Great amount energy Powerhouse

Stages of Respiration Glucose O2 Mitochondria Cytoplasm Sm. Mole. H2O Energy Sm. Mole. Energy CO2 O2 Mitochondria Cytoplasm

Comparing Photosynthesis and Respiration The equations for Photo and Resp. are OPPOSITE! Form a cycle that keeps the levels of CO2 and O2 fairly constant

Energy flow and Chemical Cycling in the Biosphere Sunlight energy Ecosystem Photosynthesis (in chloroplasts) Carbon dioxide Oxygen Glucose Respiration in many respects is the reverse of Photosynthesis Water Respiration (in mitochondria) Cellular respiration (in mitochondria) for cellular work Heat energy Figure 6.3

Fermentation Some cells obtain energy without using O2 Fermentation provides energy for cells without O2 Energy from each sugar molecule is much lower than Respiration

Fermentation in Microorganisms Various types of microorganisms perform fermentation Yeast cells carry out a slightly different type of fermentation pathway This pathway produces CO2 and ethanol Glucose  ATP + CO2 (g) + EtOH

Alcoholic Fermentation Occurs in yeast and some other single celled organisms. Alcohol is a product that is made when these organisms break down sugar Important to brewers and bakers.

Lactic Acid Fermentation Takes place in the body Muscle cells use up O2 faster than it can be replaced Cells lack O2 – fermentation occurs

A Harvest of Light: Photosynthesis Life on Earth is solar powered