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Leaf me alone

Leaf me alone. Water enters the plant through the roots and is transported to leaves by veins CO 2 enters through stomata in the leave Both H 2 O and CO 2 diffuse through the cell and enter chloroplast where photosynthesis takes place. Photosynthetic cells will contain 40 - 200 chloroplasts

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Leaf me alone

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  1. Leaf me alone

  2. Water enters the plant through the roots and is transported to leaves by veins • CO2 enters through stomata in the leave • Both H2O and CO2 diffuse through the cell and enter chloroplast where photosynthesis takes place

  3. Photosynthetic cells will contain 40 - 200 chloroplasts • 500 000 chloroplasts per square millimetre • Thylakoids inside the chloroplasts are interconnected disks…like flattened pancakes • Granum - stack of thylakoids • Molecules that absorb sunlight are found in the thylakoid membrane

  4. Light Energy and Photosynthetic Pigments

  5. Photosynthesis in 3 stages • Stage 1: light energy is captured • Stage 2: captured light energy is used to make ATP and reduce NADP (the energy transferring coenzyme used in photosynthesis) • Stage 3: Free energy of ATP and the reducing power of NADPH is used to synthesize organic compounds such as glucose, from CO2

  6. Light Reactions: these are the first 2 stages and they require light energy to function • They require chlorophyll and occur in the thylakoid membranes in chloroplasts • The light energy they absorb is transferred to stage 3 where it is used in carbohydrate molecules • The reactions in stage 3 result in carbon fixation (changes the carbon from CO2 to compounds such as glucose) • These reactions are endergonic (require the energy from ATP) • Carbon fixation takes place in the stroma by a sequence of enzyme catalyzed reactions called the Calvin Cycle • Calvin cycle also requires ATP and NADPH from the light reactions

  7. LIGHT • Light (AKA: electromagnetic radiation (EM)) is a form of energy that travels at 3 x 108 m/s in wave packets called photons • The energy of a photon is inversely proportional to it’s wavelength (long wavelength = low energy) • Photosystems are located in the thylakoid and they are responsible for absorbing photons and transfer their energy to ADP, Pi, and NADP+ forming ATP and NADPH

  8. Chlorophyll and Accessory Pigments • Chlorophylls a and b absorb blue and red regions of light • Chlorophyll a is the only one that can transfer energy to the carbon fixation reactions • Cb acts as an accessory pigment

  9. Limiting Factors of Photosynthesis • At low light intensities, the rate increases as the intensity increases, regardless of temp • At high light intensities the rate of photosynthesis increases with increasing temperature, not with increasing light intensities • Overall rate of photosynthesis decreases when the availability of CO2 is limited

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