Photosynthesis Bellringer A.1 Identify the following as: heterotroph, autotroph, photosynthesis reactant, or photosynthesis product State Biology Standards H.B.3A1-3 and H.B.2A.1 A.1 Plants take in carbon dioxide (CO 2 ) through tiny openings in leaves called stomata (singular: stoma). Stomata open and close to: Take in CO 2 Release O 2 Law of conservation Matter can not be created or destroyed BUT can be transformed. CO 2 and H 2 O are transformed into different molecules. REMEMBER from unit 2 C,H,O The carbon in carbon dioxide is used to make sugar. The oxygen that is released is the very oxygen that we ourselves need to breathe! Recall: Carbohydrates (Main energy source) CHO in a 1:2:1 ratio Lipids (stored energy/long term energy source) CHO with a lot of CH and a little O Proteins (structure) CHON Energy is stored in the bonds Bonds made= energy stored Bonds broken= energy released Photosynthesis Overview Autotrophs make their own food by trapping light energy and converting it to chemical energy (carbohydrates). Occurs in the chloroplasts Occurs in 2 main stages: 1. -dependent reactions 2. -independent reactions (a.k.a.) Calvin Cycle) Overall equation for Photosynthesis: 6 CO 2 + 6 H 2 0 + C 6 H 12 O 6 + 6O 2 1
Chloroplast Structure: Chloroplast Stroma Outer membrane Granum Thylakoid (folded inner membrane) Chloroplasts Structure of the chloroplast: Inner membrane is folded to form thylakoids, which are stacked to form grana Fluid around grana is called the stroma Thylakoid membranes contain photosystems, which contain a pigment called chlorophyll There are two types of chlorophyll chlorophyll a and chlorophyll b The two types of chlorophyll mostly absorb red and blue wavelengths of light and reflect green wavelengths of light, which is why plants look green Learning Check 1. What is the main source of Energy on earth? 2. What are the two stages of photosynthesis? 3. Where does photosynthesis occur? 4. What are the overall reactants of photosynthesis? 5. What are the overall products of photosynthesis? dependent reactions -Dependent Reactions Overview The first stage of photosynthesis Requires sunlight (AKA: -dependent reactions) Where does it happen? thylakoid membranes What goes in? sunlight (light/solar energy), water, NADP + (electron acceptor), ADP, and a phosphate group What comes out? oxygen, NADPH (energy carrying molecule), and ATP Steps of -Dependent Reactions 1. Electrons absorb light energy and become energized. 2. Those excited electrons travel through an electron transport chain pumping H+ ions into the thylakoid membranes. At the end, electron is accepted by NADP+ to become NADPH 3. Water is split into H +, O 2 and electrons. This replaces electrons (allows process to occur again) and releases oxygen as waste product back into the environment. * Through this series of reactions-- oxygen, NADPH, and ATP are produced. 2
-dependent animation Making ATP 1. H+ ions inside the thylakoid membranes are in high concentration (crowded). 2. H+ ions travel through thylakoid membranes via ATP synthase (- ase = enzyme) from inside the thylakoid lumen out to stroma. 3. ATP synthase then takes a phosphate group and adds it to ADP to make ATP. Thylakoid membrane Reactants water NADP+ ADP Products Oxygen NADPH ATP -Dependent Reactions Overview Learning Check Where do the light dependent reactions occur? What is produced in the light reactions? What is NADP+? What is NADPH? What is released into the atmosphere during the light reactions? Bell Ringer 11/6 (yes you have to draw the graph!!!) 1. What is the overall chemical equation for photosynthesis? Label the reactants and the products. 2. What are the two stages of photosynthesis? Where does each stage take place? 3. Look at the graph to the right. As carbon dioxide levels increase, plants will produce more. 4. What is happening at C in the graph to the right? independent reactions a.k.a. The Calvin Cycle 3
-Independent Reactions Overview The second stage of photosynthesis DOES NOT require sunlight (AKA dark reactions or Calvin Cycle) NADPH and ATP made in the light reactions are used to make sugars (specifically glucose) Where does it happen? stroma (fluid) of the chloroplast What goes in? NADPH, ATP, and CO 2 What comes out? glucose, ADP, phosphate group, and NADP+ Steps of -Independent Reactions 1. CO 2 enters the cycle and is attached to a 5 carbon molecule. This breaks into two 3 carbon molecules. 2. ATP and NADPH (both from light reactions) give their energy to these 3C sugars, making them more stable. Does this 6 times = 6 turns of the cycle. 3. 6 carbons link together to form glucose (6 carbon, long-term energy storing molecule) 4. NADP+, ADP, and a phosphate group are recycled back to the light reactions to be re-energized -independent animation http://www.biomanbio.com/gamesandlabs/photorespgames/photointeractive. html Try this at home and answer these questions on a separate sheet of paper for extra credit: 1) Rubisco is an enzyme that catalyzes the reaction between and. 2) ATP and NADPH are supplied by the. 3) ATP and NADPH are used to make 6 molecules of G3P. 4) One molecule of glucose results from turn(s) of the Calvin Cycle. What it looks like (RuBP) What it looks like Dark Stroma Reactants: ATP CO 2 NADPH -independent Reactions Overview Products: glucose NADP+ ADP 4
The Calvin Cycle Label each step; include ATP and NADPH State Biology Standards B-3.3 and B-3.1 5