1 / 19

PHOTOSYNTHESIS

PHOTOSYNTHESIS. From the Sun to Food. PHOTOSYNTHESIS. Photosynthesis is ability of a plant to turn sunlight, carbon dioxide , and water into sugar (food for energy storage).

evelyn
Download Presentation

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 From the Sun to Food

  2. PHOTOSYNTHESIS • Photosynthesisis ability of a plant to turn sunlight, carbon dioxide, and water into sugar (food for energy storage). • The overall reaction is: light chlorophyll 6CO2 + 6H2O -------> C6H12O6 + 6O2

  3. Photosynthesis • Photosynthesis is vital to life for two reasons • The oxygen in the air comes from photosynthesis. The plants continue to replenish the oxygen in the air. • Almost all energy on Earth and all of our food comes directly or indirectly from photosynthesis.

  4. Stages of Photosynthesis • Photosynthesis occurs in three stages: • Stage 1: Energy is captured from sunlight • Stage 2: Light energy is converted to chemical energy (temporarily stored as ATP and NADPH) • Stage 3: The chemical energy in the ATP and NADPH powers the formation of organic compounds (food) using CO2. Light Dark

  5. 5. Stage 1: Pigments capture light • Light energy captured by chlorophyll (main photosynthetic pigment) and carotenoids (fall colors). • Together they allow more wavelengths of light to be captured.

  6. 5. Stage 1 • When light strikes these pigments, energy is transferred to their electrons causing the electrons to jump to their next energy level (they get excited). • Excited electrons jump from chlorophyll to nearby molecules. • Those electrons must be replaced so special enzymes split water molecules, taking electrons from the H leaving H+ and O2 (gas).

  7. 6. Stage 2 – Conversion of Light Energy • The excited electrons that leave the chlorophyll jump through a series of molecules like a fire line • There are two series or electron transport chains which pass down these electrons.

  8. The Electron Transport Chains

  9. 7. The Products of the ETCs • One ETC provides energy to make ATP • The other ETC provides energy to make NADPH • Both of these compounds provide temporary chemical storage of the energy from the sunlight. ETC ETC Store Chem. Energy from sun NADPH ATP

  10. 8. The Light Reactions • Stage 1 and Stage 2 both require light to occur…

  11. 9. Stage 3 – Energy Storage(The Calvin Cycle – The Dark Reactions) • The dark reactions take place outside the thylakoid membrane in the stroma. • Calvin Cycle converts CO2 to sugar in a three phase process.

  12. The Calvin Cycle (continued) • Carbon fixation – CO2 is incorporated into an organic molecule (1C + 5C = 6C) called RuBP by the enzyme Rubisco. This 6 carbon structure is unstable and immediately splits into 2, 3 carbon molecules. • Reduction– Each 3 carbon molecule is phosphorylated by ATP and NAPH. One of the 3 carbon sugars is used to make starches or sugars. • Regeneration of CO2 acceptor– The other 3 carbon sugars are used to regenerate the initial 5 carbon compound…completing the cycle.

  13. 10. What factors affect photosynthesis? • Intensity of light • Scarcity of water • Temperature • Amount of carbon dioxide

  14. QUESTIONS?

More Related