Chapter 6 Photosynthesis

Photosynthesis Organisms need to have food to live. The way organisms get food differs depending on what kind of organism they are. Animals get food from the things that they eat. (plants, animals etc.) *Animals that only eat plants are herbivores. *Animals that eat only meat are carnivores. *Animals that eat both plant and animal materials are omnivores.

What goes in and exchanges, then what comes out!

Where does this take place in the plant? Where in the cell?

Light Capturing (continued) .

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Organism Types Autotrophs: these organisms make their own food. They use the energy from the light (sun) to make their food. Heterotrophs: these organisms can not make their own food they must get food from what they consume.

Autotrophs These organisms make their food by converting sun light energy to usable energy (ATP) In most autotrophs this is done by photosynthesis. These organisms use light to make their food. Photosynthesis: process that converts light energy into chemical energy in the form of organic compounds. (carbohydrates)

Photosynthesis Unbalanced Equation YOU MUST KNOW THIS!! CO2 + H2O C6H12O6 + O2 light

Balancing the equations When writing a chemical equation, what ever you put in must balance at the other end just like it does in a math problem. Six carbons in must equal 6 carbons out.

Balance the Photosynthesis Equation from before 6CO2 + 6H2O C6H12O6 + 6O2 light

Reactions Light reaction: Light energy is converted to chemical energy which is stored in ATP and the energy carrier molecule NADPH. Calvin Cycle: Organic compounds are formed using CO2 and the chemical energy stored in ATP and NADPH.

Light Capturing Happens in the chloroplasts of the plant cell(s). Thylakoids are membranes in the inner part of the chloroplast. These look like small coins. They are really flattened sacs. Grana (Granum) are where the stacks of coins are connected from one stack to another Stroma: The fluid area around the grana

Pigments Pigments are colors that absorb light energy In Plants there are many pigments that play a role in light absorption Different pigments absorb light at different wave lengths Different wave lengths have different energy

Pigments Chlorophyll – green color absorbs with the broadest pigments (color) range. Xanthophyll-Carotenoid – orange, red and brown is a weak pigment much less broad light absorption than chlorophyll

Pigmentation Photosystem is a cluster of pigments and the proteins that the pigments are attached to. There are two types of photosystems. Photosystem I and Photosystem II they play an important role in photosynthesis but in different ways.

Light reaction Step 1 Light energy forces electrons to enter the high energy level in the chlorophyll a molecules in photosystem II. These electrons are now excited and have lots of energy. The electrons now leave chlorophyll and this reaction is called an oxidation reaction.

Light reaction Step 2: Whenever an electron is lost one must be moved to be added. The acceptor for the molecule electrons of chlorophyll a is the thylakoid membrane (sac) coin. This is called the Primary Electron Acceptor

Light reaction Step 3 The primary electron acceptor donates an electron to the electron transport chain. As electrons chain the energy is lost and put into H+. The hydrogen atoms now have lots of energy in the thylakoid.

Light reaction Step 4 The light is absorbed by photosystem I. This is taking place while photosystem II is already at work. Electrons here are also moved into an excited stage and then move to another primary electron receptor. These electrons then again chain to make hydrogen atoms with energy.

Light reaction Step 5 All the excited H+ atoms join with the NADP to make NADPH which holds the energy until the cell needs it. While the electrons are moving, water is being split into usable parts. 2H2O 4H+ + 4e- + O2 Note that we have 4 electrons and 4 hydrogen atoms made here! Oxygen is also made here as a result of water splitting.

Light reaction How is ATP made???? Chemiosmosis is the making of ATP which is vital for the plant cell to work. ATP is the energy for the cell to do its work and for the bike to run. When NADPH is moving around the thylakoid the N and H are used and an additional P is added as ADP passes through the ion channel in the thylakoid membrane and ATP is made.

The Calvin Cycle This should really be called carbon fixation cycle. This cycle uses ATP and NADPH to move and combine carbon molecules into a 6 carbon molecule (sugar) CO2 is added to a carbon molecule that has four carbons becomes a 6 carbon molecule.

Quiz 6 Photosynthesis

Quiz 6 Photosynthesis 1. What is photosynthesis? 2. Where does it take place? 3. Why do we need photosynthesis?

Quiz 6 4. Write the balanced equation for photosynthesis. 5. Why are animals dependent on plants? 6. What is a pigment?

Quiz 6 7. What is the molecule that carries the energy on the chloroplast? 8. What is a stoma? 9. Describe/draw a chloroplast and its internal structures.

Quiz 6 10. What are two of the pigments in photosynthesis? 11. Explain; Why plants are so important to humans. Use what you know about the photosynthesis process, the plant cell, organelles, and the products and reactants of the equation for photosynthesis to best answer the question.