Cell Energy Photosynthesis and Respiration. Photosynthesis Process by which plants & certain other organisms use sunlight to make sugar Energy conversion-

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

• CO2 (carbon dioxide) gas enters through stomata in leaves

• H2O (dihydrogen monoxide) liquid taken in mostly by roots

Formula

sunlight

6 CO2 + 6 H2O) --- C6H12O6 + 6 O2

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

-------- CO2

O2 -----

Organisms of the O2-CO2 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/O2”• 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:• C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATP (energy)

Anaerobic Respiration

• Respiration without oxygen

• Certain organisms (like yeast) do not need O2 for respiration

• Instead they carry out fermentation

• Products = CO2 + 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