Presentation on theme: "Photosynthesis: Capturing Energy"— Presentation transcript:
1Photosynthesis: Capturing Energy Chapter 8Photosynthesis:Capturing Energy
2Photosynthesis is the process by which plants, some bacteria, and some protists use the energy from sunlight to produce sugar.Cellular respiration then converts sugar into ATP, the "fuel" used by all living things.
3Photosynthesis Conversion of light energy to chemical bond energy Associated with the green pigment, chlorophyllEquation:
4Plants Plants are the only photosynthetic organisms that have leaves. A leaf is basically a solar collector full of photosynthetic cells.
5LeavesWater enters the root and is transported up to the leaves through specialized plant cells known as xylem.Land plants (which risk drying out) have structures called stomata that allow for gas exchange.However, while open, water still escapes.
10Light Light can also behave as particles Photons – packets of energyWhen a molecule absorbs a photon of light energy, one electron is energized
11Chlorophyll Chlorophyll is a pigment Pigment is any substance that absorbs light.Chlorophyll – green pigment common to all photosynthetic cellsColor is from the wavelength of light reflectedDifferent types of chlorophyllAccessory pigments – absorb different wavelengths of light
12Pigments All photosynthetic organisms have chlorophyll a Chlorophyll a absorbs its energy from Violet-Blue and Red-Orange wavelengthsGreen/Yellow is reflectedAccessory pigments: chlorophyll b, carotenoids – absorb other wavelengths
14Chloroplasts Have a double membrane Inner membrane encloses the stroma (area between membranes)Thylakoids are a third set of membranes enclosing the thylakoid interior spaceStacks of thylakoids = granaChlorophyll and other pigments located in the thylakoid membranes
18Light-Dependent Reactions Light excites the electrons in chlorophyll a to a higher energy stateIn a series of reactions the energy is converted (along an electron transport process) into ATP and NADPH.Water is split in the process, releasing oxygen as a by-product of the reaction.The ATP and NADPH are used to make C-C bonds in the Light Independent Process (Dark Reactions)
19Calvin Cycle (Light Independent Reactions) Not driven by lightUse products from Light Dependent reactionsCO2 is captured and modified with the addition of Hydrogen to form carbohydrates