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Photosynthesis

Photosynthesis. The Essence of Photosynthesis. 1. Photosynthesis • energy from sunlight is converted into chemical bond energy in the form of carbohydrates 2 . Summary equation for photosynthesis. The Essence of Photosynthesis cont. 3. Principle ingredients a . Carbon dioxide (CO 2 )

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Photosynthesis

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  1. Photosynthesis

  2. The Essence of Photosynthesis • 1. Photosynthesis • • energy from sunlight is converted into chemical bond energy in the form of carbohydrates • 2. Summary equation for photosynthesis

  3. The Essence of Photosynthesis cont. • 3. Principle ingredients • a. Carbon dioxide (CO2) • b. Water • c. Light • d. Chlorophyll • 1) Several types • 2) All magnesium containing molecules • 3) Light harvesting complex called a photosynthetic unit • • 250-400 pigment molecules

  4. The Essence of Photosynthesis cont. • 3. Principle ingredients • a. Carbon dioxide (CO2) • b. Water • c. Light • d. Chlorophyll • 1) Several types • 2) All magnesium containing molecules • 3) Light harvesting complex called a photosynthetic unit • • 250-400 pigment molecules

  5. Introduction to the Major Steps of Photosynthesis • 1. The Light-Dependent Reactions • a. Reactions take place in thylakoid membranes of chloroplast • • light required • b. Water split, producing hydrogen ions and electrons, O2 gas released • c. ATP created • d. NADPH + H+ created

  6. Introduction to the Major Steps of Photosynthesis

  7. Introduction to the Major Steps of Photosynthesis • 2. The Light-Independent Reactions (Calvin cycle) • a. Reactions take place in stroma of chloroplast • • light not required, hence "dark" reactions • b. Calvin cycle • 1) Carbon dioxide from air combined with 5-carbon sugar • 2) Glucose formed through several reaction steps

  8. Introduction to the Major Steps of Photosynthesis

  9. Label the components of the chloroplast and what they do. • Grana – light reaction • Stroma – dark reaction • Light trapping system • E trapped and guided down to chloroplast • 2 main kinds of chlorophyll: a, and b • All light energy is transported to chlorophyll a which does the task. • B to a • C to a • Other pigments to a

  10. spectrum • Leaves absorbe the red and blue end of the spectrum. That is why leaves look green.

  11. Accessory pigments to trap light E • Xanthophylls – yellow antioxidant • Carotene – orange antioxidant

  12. A Closer Look at Photosynthesis • 1. Historical perspective • 2. The Light-Dependent Reactions Reexamined • a. Nature of light • 1) Wave and particle theory of light • 2) Photoelectric effect • 3) Photons • • discrete packets of light energy

  13. A Closer Look at Photosynthesis cont. • b. Chlorophyll pigments • • each pigment has typical absorption spectrum • c. Consequences of light absorption by chlorophyll • 1) Emit light immediately (fluorescence) • 2) Emit light after a delay (phosphorescence) • 3) Absorbed energy converted to heat • 4) Absorbed energy converted and stored in chemical bond energy (photosynthesis)

  14. A Closer Look at Photosynthesis cont. • d. Photosystem I contains • 1) 200 or more chlorophyll a molecules 2) Small amount of chlorophyll b • 3) Carotenoid pigment with protein attached • 4) Special reaction-center molecule of chlorophyll a called P700 • 5) Iron-sulfur proteins (electron acceptors)

  15. A Closer Look at Photosynthesis cont. • e. Photosystem II contains • 1) Chlorophyll a molecules • 2) ß-carotene pigments attached to protein • 3) Small amount of chlorophyll b • 4) Special reaction-center molecule of chlorophyll a called P680 • 5) Primary electron acceptor molecule called pheophytin • F. Photolysis • g. Photophosphorylation • h. Chemiosmosis

  16. A Closer Look at Photosynthesis cont. • 3. The Light-Independent Reactions Re-examined • a. The Calvin cycle (3-carbon pathway) • b. Photorespiration • c. The 4-carbon pathway • d. CAM photosynthesis • 4. Other Significant Processes that Occur in Chloroplasts

  17. The Essence of Respiration • 1. Respiration defined • • energy releasing process where simple sugars are broken down during a series of stages controlled by enzymes • 2. Summary equation for respiration • 3. Anaerobic respiration and fermentation

  18. Introduction to the Major Steps of Respiration • 1. Glycolysis • 2. Aerobic respiration • a. The Citric Acid (Krebs) Cycle • b. The Electron transport chain • 3. Anaerobic respiration and fermentation • 4. Factors affecting the rate of respiration • a. Temperature • b. Water • c. Oxygen

  19. A Closer Look at Respiration • 1. Glycolysis re-examined • a. Phosphorylation • b. Sugar cleavage • 2. Transition Step to the Citric Acid (Krebs) Cycle • a. Pyruvic acid • b. Acetyl CoA • 3. The Krebs cycle re-examined • 4. Electron transport and oxidative phosphorylation

  20. END

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