Cell Energy Photosynthesis and Respiration

Photosynthesis Process by which plants & certain other organisms use sunlight to make sugar Energy conversion- solar energy  food (sugar) Takes place in chloroplasts containing chlorophyll

Steps 1. (happens in daylight) –sunlight is captured by chlorophyll 2. (happens in light or darkness)- captured energy is used to manufacture sugar

Ingredients CO 2 (carbon dioxide) gas enters through stomata in leaves H 2 O (dihydrogen monoxide) liquid taken in mostly by roots

Formula sunlight 6 CO H 2 O) ---  C 6 H 12 O O 2 chlorophyll

Products Sugar (glucose) Oxygen, a “waste” product, not immediately used by plant

Glucose, a carbohydrate Can be Made into other simple sugars Made into starches (long strings of sugar molecules linked together in a chain) Combined with other substances to form other things needed by organism: proteins, fats, oils

Oxygen-Carbon Dioxide Cycle Gases are exchanged between organisms  CO 2 O 

Organisms of the O 2 -CO 2 Cycle Autotrophs = organisms that can carry out photosynthesis (make own food) Heterotrophs* = organisms that cannot carry out photosynthesis *must eat other organisms to obtain their energy Both take in oxygen for respiration

Aerobic Respiration Process in which energy is released in sugar when combined with oxygen Glucose molecule’s bonds are broken Energy is given off “aerobic” means “with air/O 2 ” Energy stored in ATP molecule (adenosine triphosphate)

2 Stages of Aerobic Respiration First stage takes place in the cytoplasm of cells. Oxygen is not involved, little energy released Second stage takes place in mitochondria

Occurs in all cells of an organism, especially in muscle & heart cells Takes place in the mitochondria of cells Reverse of photosynthesis Formula: C 6 H 12 O O 2  6 CO H 2 O + ATP (energy)

Anaerobic Respiration Respiration without oxygen Certain organisms (like yeast) do not need O 2 for respiration Instead they carry out fermentation Products = CO 2 + alcohol + ATP Beer, wine, bread are produced with yeast

Lactic Acid Fermentation Sometimes the need of muscles for energy is greater than the ability to obtain oxygen When this happens, muscles use anaerobic respiration to get energy and may feel tired and sore