Photosynthesis Teacher Note: Be sure to have the Prentice Hall PowerPt CD in the D: Drive to run the hyperlinked videos

How Organisms Obtain Energy Autotrophs: organisms such as plants which make their own food. Heterotrophs: organisms such as animals who cannot use the sun’s energy directly. They consume other organisms.

Storing and Releasing Energy ADP: Adenosine diphosphate. This molecule has 2 phosphates and needs another to be used for energy. This is like a half full battery ATP: Adenosine triphosphate. Has one more phosphate, three all together. When bonds are broken due to removal of phosphates, energy is released. This is like a fully charged battery. ATP Formation

ATP: A Fully Charged Battery

Photosynthesis The process where use of energy from the sun is used to convert water and carbon dioxide into sugars and starches and oxygen. 6CO 2 + 6H 2 O ––––––> C 6 H 12 O 6 + 6O 2

How light energy is absorbed Pigments: light absorbing molecules Chlorophyll: does not absorb the green wavelength of light. This is reflected which is why plants look green.

How energy is transfered Light is a form of energy. A compound that absorbs light also absorbs the energy from the light. This energy is transfered to the electrons

Parts of a chloroplast Thylakoids: Saclike membranes in the chloroplast Granum: a stack of thylakoids Photosystems: clusters of chlorophyll Stroma: space outside the thylakoid membrane

Chloroplast

Thylakoid

Chloroplast Thylakoid Granum

Chloroplast Thylakoid Granum Stroma

2 Parts of photosynthesis 1. Light dependent reactions: takes place in the thylakoid membranes uses light 2. Light independent reactions (Calvin Cycle) takes place in the stroma Does not use light Photosynthesis Parts Light Dependent Reactions Light Dependent Reactions pt.1 Light Dependent Reactions Light Dependent Reactions pt. 2

Location of Reactions

Photosynthesis Game hotosynthesis/photosynthesis_game.html

Light Dependent Reactions The electrons gain so much energy from the sun they need special carrier molecules to transport them The light dependent reactions produce oxygen gas and convert ADP and NADP+ into electron carriers ATP and NADPH.

Light Independent Reactions Also called the Calvin Cycle the ATP and NADPH formed by the light-dependent reactions contain alot of energy but can only store it for a few minutes. The Calvin Cycle uses ATP and NADPH to produce high energy sugarsCalvin Cycle

Factors that affect photosynthesis Temperature: enzymes involved in photosynthesis function best between 0°C and 35°C Water: this is one of the needed materials. A shortage can slow or stop photosynthesis Light Intensity: more light increases photosynthesis