1 / 37

Photosynthesis

Photosynthesis. Energy, from light to sugar. Photosynthesis. Photosynthesis is the process by which the energy of a photon is captured and stored in the chemical bonds of a carbohydrate. Light.

topper
Télécharger la présentation

Photosynthesis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Photosynthesis Energy, from light to sugar

  2. Photosynthesis Photosynthesis is the process by which the energy of a photon is captured and stored in the chemical bonds of a carbohydrate.

  3. Light ‘All around us, moving through us, are countless photons, little packets of pure energy, each moving as fast as possible, and each riding a wave…’

  4. Light Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm) In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum Light is composed of an elementary particle called a photon

  5. Photons • Photons are packets of energy, moving at 3x108 m/s. • As they travel they move in a waveform • The distance between two peaks is a called the wavelength • The number of wavelengths that pass in a given time period is the frequency

  6. Electromagnetic Radiation Higher frequency = short wavelength = higher energy photon

  7. Pigment A pigment is a material that changes the color of light it reflects as the result of selective color absorption (it absorbs specific photons of certain wavelengths and reflects other photons) Living organisms use pigment molecules transfer light energy to electrons The main photosynthetic pigment found in plants is chlorophyll

  8. Plant Pigments Plants use a variety of pigments to capture a larger range of the light spectrum

  9. Plant pigments

  10. Absorption spectrum The wavelengths of light absorbed by the molecular pigment chlorophyll

  11. Action spectrum The wavelengths of light absorbed by a plant

  12. Absorption vs action spectrum

  13. Engelmann’s experiment

  14. Photosynthesis Overview

  15. The Chloroplast

  16. The chloroplast

  17. Thylakoid The protein complexes involved in the light dependent reaction are located in the thylakoid membrane

  18. The Light Dependent Reaction

  19. Light Dependent Reaction • Water is split, O2 is released • electrons pass to chlorophyll at reaction center • protons are released into thylakoid lumen • Photons strike photosystem II • resonance energy excites electrons • Excited electrons are passed through electron transport chain to photosystem I • protons pumped into thylakoid lumen • ATP synthesized through chemiosmosis • Photons strike photosystem I • Excited electrons are passed to NADP+

  20. Photosystem

  21. Redox and Resonance Electrons can be donated – redox Electrons can transfer energy to nearby electrons - resonance

  22. Light dependent reaction Photolysis • water molecule is lysed by enzyme Photoactivation • e- are excited by photon energy Photophosphorylation • e- are passed through electron transport chain • ATP generated by chemiosmosis Photoreduction • e- are accepted by NADP+, it is reduced to NADPH

  23. The Light Dependent Reaction

  24. Non-cyclic Photophosphorylation Electrons move linearly through reaction from lysis of water to reduction of NADP+

  25. Cyclic Photophosphorylation Electrons reach photosystem II and are returned to electron transport chain, producing additional ATP through chemiosmosis

  26. Light dependent reaction Reactants • Water • Photon • ADP + Pi • NADP+ Products • Molecular oxygen - 02 • ATP (from chemiosmosis) • NADPH

  27. The Light independent reaction

  28. The Light independent reaction • Also known as the Calvin cycle • Occurs in the stroma of the chloroplast • Combines CO2 with electrons from NADPH and energy supplied by ATP • Ribulose biphospate (RuBp) is the initial reactant and the final product • Rubisco adds CO2 to RuBp (carbon fixation) • Each turn creates 1 G3P (3 carbons) that exits the cycle • 2 G3Ps are then combined to make 1 glucose

  29. The Light Independent Reaction:The Calvin Cycle

  30. The Calvin Cycle

  31. Reactants RuBp NADPH ATP CO2 Products RuBp NADP+ ADP + Pi G3P The light independent Reaction

  32. Factors affecting rate of photosynthesis The rate of photosynthesis can be measured directly by oxygen production, or indirectly by increase in biomass Several variables will influence the rate of photosynthesis • Light intensity – amount of sunlight • Atmospheric carbon dioxide concentration • Temperature

  33. Limiting Factor The variable which determines the rate of photosynthesis is called the limiting factor The limiting factor will vary between environments

  34. Rates of photosyntesis

  35. Factors affecting rate of photosynthesis Can you give a reasoned explanation for the shape of these curves?

  36. Review Write a description of the light dependent reaction, include… • Photolysis, photoactivation, photophosphorylation, and photoreduction Explain how the light independent reaction (calvin cycle) uses the products of the light dependent reaction. From memory draw the graphs showing the effects of the three factors that limit the rate of photosynthesis.

More Related