Chapter 8 Cellular Energy 8.1 How Organisms Obtain Energy Autotrophs Autotrophs are organisms that obtain energy by making their own food. (sugar-glucose)

What do we call the energy sources (molecules) that are used for biological chemical reactions? ATP and NADPH

ATP ATP and NADPH are both biological energy storage molecules ATP: adenosine triphosphate ATP is the most important provider of chemical energy

ATP Structure

ATP

ATP: The Unit of Cellular Energy Chapter 8 Cellular Energy 8.1 How Organisms Obtain Energy ATP: The Unit of Cellular Energy ATP releases energy when the bond between phosphate groups is broken

Forms adenosine diphosphate (ADP) and a free phosphate group.

Think of ATP as a fully charged battery ADP (adenosine diphosphate) as a half charged battery AMP (adenosine monophosphate) as an empty battery Which provides the most energy?

How is ATP made?

ATP is formed during photosynthesis

Photosynthesis: the process by which green plants use the light energy to produce carbohydrates 6CO2 + 6H2O → C6H12O6 + 6O2 carbon dioxide + water (light) glucose + oxygen

In other words, light energy is converted into chemical energy!

Photosynthesis occurs in two phases. Chapter 8 Cellular Energy 8.2 Photosynthesis Photosynthesis occurs in two phases. Light-dependent reactions Light-independent reactions (Calvin Cycle)

Light Dependent Reaction Energy from the sun is absorbed by the chloroplasts found mainly in green leaves The light energy is used to produce two energy-storing molecules ATP and NADPH

Leaf Cells with Chloroplasts

The light dependent reaction occurs in the thylakoids where the chlorophyll (green pigment) is located A stack of thylakoids is called a granum Stroma: Fluid-filled area outside of the thylakoid (put in your notes)

Draw the Following:

The O2 is released as waste Light energizes the electrons found in the chlorophyll molecules The light energy also causes a water molecule to split into 2 hydrogen and one oxygen The O2 is released as waste

Through a series of events, the excited electrons are transported to an electron carrier called NADP+ The electrons bond to the NADP+ and form the chemical energy-storage molecule NADPH

The H+ (hydrogen ions) stay in the thylakoid and accumulate until they move out of the thylakoid space through ion channels called ATP synthases As H+ moves through ATP synthase, ATP is formed in the stroma from ADP

ATP Synthase Thylakoid Stroma

ATP and NADPH are not stable enough to store energy for long periods of time Instead, it is stored as glucose in the plant This occurs during the second phase of photosynthesis called the Calvin Cycle or the Light Independent Reaction

Light Independent Reaction (Calvin Cycle) Light Independent Reaction: uses energy stored in ATP and NADPH to make glucose Occurs in the stroma during light or dark

Light Independent Reaction Hydrogen and energy from the light reaction combine with CO2 from the atmosphere to form glucose Glucose can store energy for long periods of time 6CO2 + 6H2O → C6H12O6 + 6O2