9.1~Cellular Respiration: An Overview

-Organisms get the energy they need from food.

~There is a lot of energy in food, & it's

expressed in calories

~Cells gradually break down food molecules & use the energy to

produce compounds such as ATP.

-Cellular respiration-the process that releases energy from food in the presence of oxygen.

~6O2 + C6H12O6 ----> 6CO2 + 6H2O + Energy Oxygen + glucose ----> carbon + water + energy

dioxide

-There are different stages of cellular respiration so the energy is controlled when it's released.

1. glycolysis: glucose enters the cell & a small amount of ATP is captured. Anaerobic process. Takes place in the cytoplasm of a cell.

2. Krebs Cycle-glucose goes through the cycle & a little bit more energy is captured. Aerobic process. Takes place in the mitochondria.

3. Electron Transport Chain-the reactants of the other stages are used to generate the bulk of the energy. Aerobic process. Takes place in the mitochondria.

-Photosynthesis removes carbon dioxide from the atmosphere & cellular respiration puts it back. Photosynthesis releases oxygen into the atmosphere & cellular respiration uses that oxygen to release energy from food.

-plants use sugars to produce complex carbohydrates & provide energy for synthesis of other compounds

-light-dependent reactions~first set-they require the direct involvement of light & light absorbing pigments.

~the reaction uses energy from sunlight

to produce energy-rich compounds like

ATP.

Light-dependent & Light-independent Reactions

-light-independent reactions~ATP & NADPH molecules produced in the light-

dependent reactions are used to produce high- energy sugars from carbon dioxide ~this requires no light & takes place in the

stroma

-both types of reactions work together to capture the energy of sunlight & transforms it into energy-rich compounds.