Photosynthesis

1. Photosynthesis Ch 8 Notes

2. Energy • Energy • The ability to do work (fuel) • Autotrophs • Organisms that have the ability to use light energy (sunlight) in order to produce food • Plants, algae, and some bacteria • Heterotrophs • Organisms that must consume food in order to obtain energy • Animals, fungi, and bacteria

4. Chemical Energy • Since heterotrophs cannot use the sun’s energy directly, energy must be stored chemically • Chemical energy can be found in high energy bonds • Most principle chemical compounds that cells use to store and release energy…ATP (adenosine triphosphate)

5. ATP • Consists of 3 parts • Adenine • Ribose (sugar) • 3 phosphate groups • Storing energy • When a phosphate group is added to an ADP (adenosine diphosphate) molecule (ADP + P) • Releasing energy • When ATP is reduced (broken down) into ADP + P

6. ATP Molecule

7. How ATP & ADP Work Hyperlink to Textbook

8. Photosynthesis • The conversion of light energy into chemical energy which is stored within organic compounds. • Involves a complex series of chemical reactions, in which the product of one reaction is consumed in the next reaction, this is called a biochemical pathway. • Translation: plants turn sunlight into sugar that organisms (like you) can use for energy

9. The Photosynthesis Equation 6 CO2 + 6 H2O + light energy  C6H12O6 + 6 O2 Carbon dioxide + water + light energy YIELDS glucose (carbohydrate) + oxygen

10. Overview of the photosynthetic process

11. Light and Pigments • In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll • Chlorophyll (more like boraphyll, ha) is a pigment inside chloroplasts that absorbs light energy from the sun • Light is white, and chlorophyll absorbs all the visible light rays except green • Translation: this makes plants green in color

12. The electromagnetic spectrum

13. Structures of Photosynthesis • Chloroplast • Organelle in cell that is contains thylakoids and is the site of photosynthesis • Thylakoids • Photosynthetic membranes that organize pigments • Granum • Stacks of thylakoids inside chloroplasts • Stroma • Region inside chloroplast yet outside thylakoids

15. Electron Carriers • When sunlight excites electrons in chlorophyll, the electrons gain a great deal of energy. These high-energy electrons require a special carrier • A carrier molecule is a compound that can accept a pair of high-energy electrons and transfer them along with most of their energy to another molecule. • This process is called electron transport, and the electron carriers themselves are known as the electron transport chain.

16. How They Work • NADP+ accepts and holds 2 high-energy electrons along with a hydrogen ion (H+) • This converts the NADP+ into NADPH • The NADPH can then carry high-energy electrons produced by light absorption in chlorophyll to chemical reactions elsewhere in the cell

17. Light Dependent Reaction • Reactions that require light to produce oxygen gas and convert ADP and NADP+ into the energy carriers ATP and NADPH

18. Input & Output • Reactants: • Light energy, H2O, NADP+, ADP • Products: • O2, ATP, NADPH

19. Calvin Cycle • The Calvin cycle uses ATP and NADPH from the light dependent reaction to produce high energy sugars • Occurs in the stroma of the chloroplast • Does not require light

20. Input & Output • Input: • CO2, ATP, NADPH • Output: • Sugar, ADP, NADP+

21. Put it All Together!

22. Video Clip • Textbook hyperlink