Cell Processes and Energy

Sources of Energy Nearly all living things obtain energy either directly or indirectly from the sun. Autotroph - An organism that makes its own food. Heterotroph - an organism that cannot make its own food.

Photosynthesis Photosynthesis - A two staged process by which a cell captures energy in sunlight and uses it to make food. The raw materials for photosynthesis are carbon dioxide (CO2) and water. The products of photosynthesis are oxygen (O2) and sugar(C6H12O6).

Photosynthesis: Stage 1 The sun’s energy is captured in a plant’s leaves. Pigments are colored chemicals that absorb light. Chlorophyll is the main photosynthetic pigment in chloroplasts. Makes plants green. Chlorphyll’s function is capture light energy for use in the 2nd stage of photosynthesis.

Photosynthesis: Stage 2 Captured energy is used to make food for the plant. Water is absorbed through the roots. CO2 enters the plant through the stomata. Stomata (stoma - singular) are small openings on the underside of a leaves.

Photosynthesis: Stage 2 The raw materials for photosynthesis (CO2 & H2O) travel to the leaves, and more specifically to the chloroplasts. In the chloroplasts, a complex series of chemical reactions take place. These reactions are powered by the sunlight captured in Stage 1. There are 2 products of photosynthesis - C6H12O6 and O2.

Photosynthesis Equation The subscript indicates the # of atoms. The coefficient indicates the # of molecules. The arrow means “yields”. 6CO2 + 6H2O  C6H12O6 + 6O2

Additional Information What happens to the sugar produced during photosynthesis? Used for cellular functions Convert some sugar into other compounds, such as cellulose. Some sugar molecules are stored for later use. (When you eat a carrot, you are eating the plant’s stored energy from the sun.)

Respiration Respiration is the process by which cells obtain energy from glucose. During respiration, cells break down simple food molecules such as sugar and release the energy they contain.

Storing Energy How do animals store energy? Animals store energy in the form of fat.

Breathing and Respiration Respiration has 2 meanings: Breathing A cellular process that converts sugar into energy for use in cellular processes.

Respiration: Stage 1 Takes place in the cytoplasm of the organism’s cell. Glucose is broken down into smaller molecules. A small amount of energy is released here.

Respiration: Stage 2 Takes place in the mitochondria. The smaller molecules from Stage 1 are broken down into even smaller molecules. The chemical reactions require oxygen. Releases a large amount of energy.

Respiration Equation NOTE: The cellular respiration equation is the photosynthesis equation reversed. Chemical energy in the form of ATP. (adenosine triphosphate) C6H12O6 + 6O2  6CO2 + 6H2O + energy

ATP Often called the “molecular unit of currency” of intracellular energy transfer. ATP transports chemical energy within the cells for metabolism.

Relationship between Photosynthesis and Cellular Respiration Draw in products of photosynthesis and raw materials for cellular respiration. Along with the products of cellular respiration and the products of cellular respiration. STUDENTS WILL NEED TO REPRODUCE THIS DIAGRAM FOR TEST!

Fermentation A process by which organisms obtain energy, that does not require oxygen. Lower amount of energy is released during fermentation than respiration.

Two types of fermentation Alcoholic Fermentation - Occurs when yeast and some other single-celled organisms break down sugars. Called alcoholic fermentation because alcohol is one of the products. Other products are CO2 and a small amount of energy. CO2 is important to bakers and brewers because the bubbles provide a specific characteristics to their goods.

Two types of fermentation Lactic Acid Fermentation occurs when your muscles experience anaerobic circumstances. Anaerobic means without oxygen. A product of lactic acid fermentation is lactic acid. ATP is also produced at a high rate. ATP is adenosine triphosphate. ATP is the primary method of energy transfer within a cell.