Photosynthesis Energy and Life All living things need

Photosynthesis Energy and Life

All living things need energy n All energy on this planet starts with the sun

Autotrophs and Heterotrophs Autotrophs are organisms that can make their own food n Plants and some other organisms can make food from sunlight = photoautotroph n Some organisms make their own food chemically from rock or soil = chemoautotroph n

Autotrophs and Heterotrophs n Heterotrophs are organisms that must consume food to get energy n a. animals eat other organisms n b. some fungus feed off of dead organisms

Chemical energy in ATP (adenosine triphosphate) n ATP is the chemical fuel used to power all cell activities

Chemical energy in ATP (cont) n a. adenine – nitrogen containing compound n b. sugar – ribose n c. triphosphate – three phosphate groups (adenosine diphosphate has two phosphate groups)

n ATP and ADP can be converted back and forth as the need for energy fluctuates n if energy needs to be stored, ADP is converted to ATP by adding a phosphate group n if energy needs to be used, ATP is broken down to ADP because breaking off that last phosphate creates LOTS of energy

n n n ATP is the basic energy source for all cells ATP and Glucose n ATP is ideal for storing a small amount of readily available energy n Glucose contains 90 times as much energy as 1 ATP; better storage material Glucose is easily converted to ATP + other energy molecules

Photosynthesis: An Overview n In photosynthesis energy from sunlight is used to convert water and carbon dioxide into sugar

Investigating Photosynthesis n Van Helmont’s Experiment – determined that the mass of a plant comes mostly from water; “hydrate” part of carbohydrate (“carbo” part comes from carbon dioxide)

Investigating Photosynthesis n However, he didn’t realize that the carbon in the air (carbon dioxide) makes sugars & contributes to the mass of his tree.

Investigating Photosynthesis n Priestley’s experiment – discovered two things with his experiment: candles need something (oxygen) in the air to burn, and plants produce that something (oxygen) that candles need to burn

Investigating Photosynthesis n Jan Ingenhousz – revealed that Priestley’s experiment only worked in the presence of light n Summation of conclusions – when light is present; plants convert carbon dioxide and water into carbohydrates and oxygen

The photosynthesis equation n 6 CO 2 + 6 H 2 O light C 6 H 12 O 6 + 6 O 2 n Plants can “string” simple sugars together to make starches