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Photosynthesis

Photosynthesis. Chapter 8. Energy in Living Systems…. Energy is the ability to do work. Autotrophs – Living things that can use energy from the sun or chemicals to make their own food. Green plants and some bacteria and algae.

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Photosynthesis

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  1. Photosynthesis Chapter 8

  2. Energy in Living Systems…. • Energy is the ability to do work. • Autotrophs – Living things that can use energy from the sun or chemicals to make their own food. Green plants and some bacteria and algae. • Heterotrophs – living things that must eat other living things for energy.

  3. Energy in Cells… • ATP, or adenosinetriphosphate is the form of energy cells make to do everyday functions. • ADP, or adenosine diphosphate is ATP without the final phosphate group. Therefore it has less energy than ATP. • ADP is used over and over again to be turned into ATP.

  4. What does ATP look like? *Only a small amount of ATP is on hand at a time, It is just regenerated over and over again!

  5. How do plants make ATP and other molecules for long term energy? • Photosynthesis – Plants use the energy in sunlight to turn water and carbon dioxide into carbohydrates and oxygen. 6H2O + 6CO2 ----------> C6H12O6+ 6O2

  6. Scientists who contributed to our knowledge of photosynthesis: • Jan van Helmont– concluded most of the mass of a tree comes from water (*partially true) • Joseph Priestley – used a bell jar, candle, and mint plant to conclude plants release oxygen • Jan Ingenhousz– concluded aquatic plants only produce oxygen bubbles in the presence of sunlight

  7. Jan van Helmont’s experiment Jan Ingenhousz’s experiment

  8. Pigments of Photosynthesis… • Chlorophyll – green pigment in plants that absorbs blue-violet and red, and reflects green. • Chlorophyll is present in the chloroplasts of a plant cell.

  9. Structure of a Chloroplast…

  10. Structure of a chloroplast… • The light-dependent reactions take place on the thylakoid membrane. Thylakoids are the “pancake” structures. Stacks are called grana. • The Calvin cycle takes place in the stroma (the fluid the thylakoids float in).

  11. Making ATP using light energy.. • The energy from the sun is absorbed by the chlorophyll in the thylakoid membrane. • NADP+ is an electron carrier that carries high energy electrons and two hydrogen ions. Turns into NADPH. • The H+ ions are created when sunlight hits the thylakoid and water is split, creating free oxygen, a waste product.

  12. Light reactions, continued… • The NADPH carries the electrons and the H+ ions to the membrane where the H+ ions are pumped into the inside of the thylakoid. • The pressure of the H+ ions builds up, and the H+ ions are forced back out of the membrane through a structure called ATP synthetase.

  13. Making ATP… • As the H+ ions and their energy move through the ATP synthetase, the protein rotates and creates 3 ATPs for every turn.

  14. 1948 – Melvin Calvin traces the path of carbon: the Calvin Cycle… • The ATP and the NADPH created in the light-independent reactions combined with carbon dioxide to assemble carbohydrates in the Calvin Cycle. • The Calvin cycle can also produce other sugars, amino acids, and lipids.

  15. The Calvin cycle…

  16. Factors affecting photosynthesis: • Water – a shortage of water will slow or stop photosynthesis. • Temperature – Plant enzymes function in specific temperature ranges. • Lightintensity – The brighter the light is, the more photosynthesis can occur. But only to a certain extent.

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