1. PHOTOSYNTHESIS Energy & Life Biology I

2. Energy & Life Where does the energy that living things need come from? Plants & other organisms are able to use light energy from the sun to produce food. Organisms such as plants make their own food & are called______. Organisms such as animals can’t make their own food & are called___.

3. Chemical Energy & ATP Energy comes in many forms, including light, heat, & electricity. The activities of the cell are powered by chemical fuels. One of the major chemical compounds is adenosine triphosphate (ATP. The molecule consists of a nitrogen containing compound called adenine, a 5- carbon sugar, and three phosphate groups

4. The ATP molecule is composed of three components. At the centre is a sugar molecule, ribose (the same sugar that forms the basis of DNA). Attached to one side of this is a base (a group consisting of linked rings of carbon and nitrogen atoms); in this case the base is adenine. The other side of the sugar is attached to a string of phosphate groups. These phosphates are the key to the activity of ATP. The Structure

5. Chemical Energy cont… ADP (adenosine diphosphate) has a similar structure to ATP, but with some differences. It has two phosphate groups. The energy storage is also different Both ATP & ADP both contain stored energy Comparing ATP to ADP….ATP is like a fully charge battery with energy ready to be used and ADP is like a partially charged battery Energy stored in ATP is released when ATP is converted into ADP & a phosphate group.

6. Releasing Energy Cells may use the energy for activities such as:  Active transport  Movement of organelles Cells may regenerate ATP from ADP as needed by using energy in carbohydrates like glucose.

8. What is Photosynthesis? light energy (photons)water (H 2 O)organic macromolecules (glucose). It’s a series of reactions that uses light energy (photons) and water (H 2 O) to produce organic macromolecules (glucose). 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Sunlight Glucose

9. Where does photosynthesis take place? Occurs in all autotrophic organisms that contain the green pigment chlorophyll Algae, blue-green bacteria, phytoplankton … Leaves of plants

10. Chloroplasts in Leaves Chlorophyllsunlight photosynthesis Chlorophyll traps sunlight, the energy for photosynthesis

11. Where in plants does photosynthesis occur? photosynthesis mesophyll cells Most photosynthesis takes place in mesophyll cells in the leaves of plants Stomata (opening) Mesophyll Cell Chloroplast

12. Mesophyll Cells of Leaf Palisade Mesophyll Spongy Mesophyll

13. What is the job of Stomata (stoma)? Pores watergases Pores in a plant’s cuticle through which water and gases are exchanged between the plant and the atmosphere. Guard Cell Carbon Dioxide (CO 2 ) Oxygen 0 2

14. Job of the Chloroplast Organellephotosynthesis Organelle where photosynthesis takes place. Granum Thylakoid Stroma Outer Membrane Inner Membrane

15. Interior of a Chloroplast

16. Thylakoids Thylakoid Membrane Thylakoid Space Granum Thylakoids form stacks called Granum which are connected to each other

17. Light & Pigments Plants, humans, and leaves gather the sun’s energy with light absorbing molecules called pigments. Light is made of particles called photons that move in waves. Sunlight is visible as white light; you can separate white light into it’s component colors by passing the light through a prism.

18. Why are plants green? Chlorophyll is the green coloration in leaves Chlorophyll is the molecule that absorbs sunlight and uses its energy to synthesize carbohydrates from CO 2 and water This process is known as photosynthesis

19. Chlorophyll Molecules thylakoid membranes Located in the thylakoid membranes Mg + Chlorophyll have Mg + in the center Chlorophyll pigments absorbing wavelengthsblue-420 nm Chlorophyll pigments harvest energy (photons) by absorbing certain wavelengths (blue-420 nm and red- 660 nm are most important) Plantsgreen wavelengthreflectednot absorbed Plants are green because the green wavelength is reflected, not absorbed

20. During the fall, what causes the leaves to change colors? As the chlorophyll in leaves decays in the autumn, the green color fades and is replaced by the oranges and reds of carotenoids

21. Photosynthetic Reactions Two main parts (reactions) Light Reaction or Light Dependent Reaction produces energy from sunlight in the form of ATP & NADPH

22. Photosynthesis is a complex reaction that can be broken down into the two following reaction systems: light dependent & light independent or dark reactions Light Dependent Reaction:  H 2 O  O 2 + ATP + NADPH 2 Water is split, giving off oxygen. This system depends on sunlight for activation energy. Light is absorbed by chlorophyll a which "excites" the electrons in the chlorophyll molecule. Electrons are passed through a series of carriers and adenosine triphosphate or ATP (energy) is produced. Takes place in the thylakoids.

23. Dark Reaction:  ATP + NADPH 2 + CO 2  C 6 H 12 O 6 Carbon dioxide is split, providing carbon to make sugars. The ultimate product is glucose. While this system depends on the products from the light reactions, it does not directly require light energy. Includes the Calvin Cycle. Takes place in the stroma.

24. Factors Affecting Photosynthesis Water~ major component Temperature~ depends on enzymes that function at optimal temps. Light intensity~ increasing light will increase rate of photosynthesis