Photosynthesis

1. Photosynthesis Chapter 8

2. Without the ability to obtain and use energy, life would cease to exist

3. Autotrophs and Heterotrophs • Plants and other types of organisms are able to use light energy from the sun to produce food. • Other animals such as heterotrophs obtain energy directly by eating other animals or the plants themselves.

4. Chemical energy and ATP • Adenosine Triphosphate: principal chemical compounds that cells use to store and release energy. • Consists of adenine, a 5- carbon sugar called ribose, and three phosphate groups

6. Energy Storage • Adenosine Diphosphate (ADP) • compound looks almost like ATP except that it has two phosphate groups instead of three. • Store ADP and adds a phosphate group to it when needed = ATP

7. Releasing Energy • Breaking the chemical bond between the second and third phosphates, it is released • Has enough energy to power a variety of cellular activities • including active transport, protein synthesis, and muscle contraction

8. Figure 8-3 Comparison of ADP and ATP to a Battery Section 8-1 ADP ATP Energy Energy Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP) Partially charged battery Fully charged battery

9. Van Helmont’s Experiment • 1600’s • Devised an experiment to find out if plants grew by taking material out of the soil. • Determined the mass of a pot of dry soil and a small seedling • Then planted it • Mass of the soil was unchanged • Concluded: mass came from water

10. Priestley's Experiment • Took a candle, placed a glass jar over it and watched as the flame gradually died out • Found out if he placed a live sprig of mint under the jar and allowed a few days to pass, the candle could be relighted and would remain lighted for a while • Mint plant had produced the substance required for burning

12. Jan Ingenhousz • showed that the effect observed by Priestley occurred only when the plant was exposed to light.

13. Photosynthesis Equation • 6CO2+ 6H2O --C6H12O6 + 6O2 • Uses the energy of sunlight to convert water and carbon dioxide into high- energy sugars and oxygen

14. Photosynthesis: Reactants and Products Section 8-2 Light Energy Chloroplast CO2 + H2O Sugars + O2

15. Light and Pigments • Requires light and chlorophyll • Sunlight is a mixture of different wavelengths of light • Visible spectrum: wavelengths that are visible to your eyes • Pigments: light absorbing molecules • Two main types of chlorophyll • Chlorophyll a and chlorophyll b

16. Chlorophyll • Absorbs light well in the blue- violet region and red regions • Does not absorb light well in the green region of the spectrum • Also contain red and orange pigments such as carotene

17. Inside a Chloroplast • Thylakoids: saclike photosynthetic membranes • Stroma: liquid region outside the thylakoid membrane • Reactions have two parts: • light dependent • light independent

19. Electron Transport • NADP+: accepts and holds 2 high energy electrons • Converts NADP+ to NADPH

20. Light Dependent Reactions • Require light • produces ATP and NADPH

21. Process • Chlorophyll absorbs light. • Light energy is absorbed by electrons, increasing energy level • Water is split into two H+ and Oxygen is released into the air • NADP+ carries Hydrogen into the Calvin cycle • ATP is made

22. Light Independent Reaction • Calvin Cycle: uses ATP and NADPH from the light-dependent reactions to produce high-energy sugars • Does not require light

23. Process • carbon dioxide molecules enter the cycle from the atmosphere • Carbon molecules are then converted into higher-energy forms called glucose • ATP used • 2 of the carbon molecules are removed from the cycle for use in the plant

24. 5. the remaining carbon molecules are cycled back to start the next cycle