Section 2 Cell energy All cells need energy to live, grow, and reproduce. Plant cells get their energy from the sun Many animal cells get the energy they need from food

From the sun to the cell Energy flows from: Sun Plants Animals Photosynthesis is the process by which plants, algae, and some bacteria (they all contain chlorophyll) use sunlight, carbon dioxide, and water to make food.

Photosynthesis Chlorophyll is the main pigment (molecule that absorbs light) used in photosynthesis Chlorophyll is green in color and found in the chloroplast. Carbon dioxide + water glucose + oxygen 6 CO2 + 6 H2O + light C6H12O6 + 6 O2

Glucose Glucose is a simple sugar carbohydrate Plants store the sun’s energy in glucose, which will be later used by the plant’s cells. Remember a plant makes its own food exactly like your mom is cooking the food at home. Both the plant and your mother need to eat this food later on in order to get the energy they need

Cellular respiration The process by which cells use oxygen to produce energy from food Most complex organisms, such as plants and animals, obtain energy through cellular respiration C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy (ATP) Glucose + oxygen carbon dioxide + water

Cellular respiration takes place in: The cell membrane prokaryotic cells The mitochondria eukaryotic cells Did you notice something?! The 2 equations are very similar.. Actually they are the same but just the opposite !!! see figure 3 p 96

Fermentation The breakdown of food without the use of oxygen Fermentation releases less energy than cellular respiration

2 types of fermentation happen in: Your muscles in case of vigorous exercise when the muscle cells can’t get the oxygen they need for cellular respiration. It produces lactic acid which builds up and contributes to muscle fatigue and causes a burning sensation. It happens also in the muscle cells of other animals and in some fungi and bacteria Yeast and bacteria and it produces CO2