Photosynthesis PHOTOSYNTHESIS

Today’s Objectives Given information and/or diagrams on the process of photosynthesis, write and/or identify the equation, raw materials, sites, products, factors affecting the process, and the role of chlorophyll in the light and dark reactions.

Photosynthesis What molecule serves as the primary energy source for metabolism? What process forms the basis of almost all food chains on Earth?

ATP: The Cell’s Currency Adenosine Triphosphate Energy from food is converted into high energy bonds in ATP ADP + P + energy  ATP

Photosynthesis 6 CO2 + 6 H2O + E  C6H12O6 + 6 O2 Basis of most of the earth’s food chains Produces and maintains all of the earth’s atmospheric oxygen Most oxygen produced in the oceans

Photosynthetic Pigments Mostly chlorophyll a and chlorophyll b Accessory pigments: Carotenoids Anthocyanins Each pigment absorbs a particular wavelength of light in the visible spectrum

Pigment Absorption

Overview of Photosynthesis

Step I: Light Reactions Involves the splitting of water (photolysis) 12 H2O + Energy  6 O2 + 24 H+ + 24e- Requires light for the energy to split the water molecule Also forms a highly energetic compound, adenosine triphosphate (ATP)

Overview of the Light Reactions Think of the light reaction, as a process by which organisms "capture and store" radiant energy as they produce oxygen gas. This energy is stored in the form of chemical bonds of compounds such as NADPH and ATP.

Step II: Dark Reactions Does not require light but can happen at any time of day. The energy from NADPH and ATP is used for carbon fixation 6 CO2 + 24 H+ + 24 e-  C6H12O6 + 6 H2O The chemical bonds present in glucose also contain a considerable amount of stored (potential) energy.

Overview of the Dark Reactions Carbon dioxide is broken and “fixed” into glucose or fructose molecules in the CALVIN CYCLE!!!! Glucose subunits can make cellulose or other polysaccharides, such as fruit sugars. The carbon skeleton in glucose also helps to synthesize other important biochemical compounds such as, lipids, amino acids, and nucleic acids.

Overview of Photosynthesis

Diagram of Photosynthesis

http://www.youtube.com/watch?v=mYbMPwmwx88