Photosynthesis

Photosynthesis Photosynthesis is the production of carbon compounds in cells using light energy. This process uses the energy from light to produce oxygen(O2) and carbohydrates from water(H2O)and carbon dioxide(CO2) Photolysis – The cutting of 2 Water into 4 H+ ions and one O2

Leaf Structure

Leaf Structure Cuticles: Waxy waterproof layer – Minimizes evaporation Upper Epidermis : Clear layer of cells – Allow sunlight to pass to the chloroplasts Palisade Mesophyll: Chloroplasts are packed here Spongy Mesophyll: Gas Exchange occurs here Lower Epidermis: Contain pores called stomata Stomata: Small holes that control the release of O2 and the uptake of CO2

Chloroplast Structure Photosynthesis occurs in the chloroplasts of plant leaf cells Chloroplast structure includes Double membrane Grana Look like a stack of coins Membrane is called the “thylakoid membrane” Stroma Fluid surrounding the grana Chlopophyll – Pigment in plant cells that absorbs red and blue wavelengths of light.

Absorption vs Action

Absorption vs Action this phenomenon can be demonstrated by an absorption spectrum, which shows chlorophyll’s light absorption vs. wavelength of light, or an action spectrum, which shows the effectiveness of different wavelengths of light at driving photosynthesis

Chloroplasts Structure/Function The chloroplast structure is closely related to its function Has an intricately folded membrane that provides more surface area for light absorption These foldings form the thylakoids, which, when stacked upon each other, form grana

The thylakoids provide a small space inside for the accumulation of protons to use in ATP production The fluid in the chloroplast (stroma) has enzymes that are used in the Calvin cycle (aka Rubisco)

Photosynthesis Limiting factors in photosynthesis Limiting factors are conditions that are essential for the life of the plant Can affect how well the plant can photosynthesize and thus how well it survives

Many plants prefer a particular amount of light intensity Various plants have different requirements in terms of how much carbon dioxide they need (think about C4 plants vs. C3 plants) Plants also need specific amounts of water to survive Temperatures must also be within a certain range for different plants to survive pH is critical to a plant’s survival as a change in the pH can effect the proteins’ structure

Overview Photosynthesis consists of light-dependant and light-independent reactions Light-dependent reaction (aka photolysis) Consists of Photosystems I and II Occurs in the thylakoid membrane of the grana Thylakoid membrane contains chlorophyll (pigment that absorbs red and blue light and reflects yellow and green)