Photosynthesis

How is Sugar Made? Photosynthesis Making sugar from sunlight Like a two act play Act I: Light Reaction “photo” Act II: Calvin Cycle “synthesis”

Setting Chloroplast Located in the leaves of plant

Chloroplast

Cast Chlorophyll- a light catching pigment CO2 – an inorganic gas H2O - water ATP – molecule that stores & releases energy NAD+, NADP+ & FADH – Carry electrons around to make energy

Overall Plot H2O and CO2 will come together in the chloroplast to produce a molecule of glucose In the process there will be a waste product produced, oxygen

Plot as a Formula

Funding For this Performance Sunlight Without the generous donation of energy from the sun this performance would not be possible

Act One Light Reaction “photo” Convert solar energy to ATP and NADPH ATP – molecule that stores and releases chemical energy NADPH – electron carrier, brings electrons and protons around cell to make energy

Act One Plot Overview Use the suns energy to: Excite the chlorophyll Split the water producing Oxygen gas as a waste product Make energy (ATP & NADPH) the players needed for Act 2

Scene Takes place in the thylakoids Membrane stacks in the chloroplast Contain enzymes to work with light reaction

Scene Continued Sunlight strikes the chlorophyll An electron is lost from chlorophyll Water is split to replace this lost electron This daring act of water produces a waste product Oxygen Gas The electron that left chlorophyll goes to work to make ATP and NADPH

The Result of Act One (The Green Area) ATP and NADPH have been made Oxygen has been released as a waste product

Act Two Calvin Cycle (Light Independent Reaction) Uses CO2 and Energy to make Sugar “synthesis”

Act II Overall Plot The energy made in the Light Reaction will add Hydrogen to CO2 to make C6H12O6 Glucose

Act II Takes place in the stroma A cycle The fluid part of the chloroplast A cycle Goes around twice to make one glucose molecule

Act II CO2 enters the cycle It will combine with a 5 carbon molecule - RuBP This combination causes a rearrangement of carbons to make a molecule that is a sugar

Act II (cont.) Six CO2 molecules are needed to make one usable glucose The carbon atoms not used in making glucose are used to continue the cycle .

Calvin Cycle (Blue Portion of Diagram)

Plot Details The next 4 slides provides details of the events of photosynthesis Use this to follow the steps in the plot With each slide find the cast member in the diagram

Plot Detail 1 CO2 enters the cycle It will combine with a carbon based molecule RuBP

Plot Detail 2 This combination creates a new molecule PGA

Plot Detail 3 The PGA is rearranged into G3P a sugar ATP gives the energy Two G3P will leave to make sugar or starch

Plot Detail 4 The remaining G3Ps will rearrange to form RuBP to continue the cycle ATP gives the energy

Act II Summarized The Calvin cycle uses energy from Act I In the form of ATP & NADPH No light is needed The energy is used to turn a 5 carbon molecule + CO2 into glucose Also to make more of the 5 carbon based molecule necessary for the cycle to continue

SO What? Light energy is used to transfer electrons from H2O to CO2 to make sugar. In the process Oxygen is released as a waste product All the Oxygen we breathe has been made this way Without oxygen, animals, plants, some bacteria any aerobic organism would not be alive.

So What Else? Glucose is used to make energy in cellular respiration Without photosynthesis heterotrophs (humans too) have no source of energy

Aerobic Needs air for the process to occur

Heterotroph Uses another source for food

Do Now Questions (Light Dep.) Name two reactants of the light reactions. Where in the chloroplast do the light reactions take place? Name the three products of the light reactions. Label each product as either energy storage molecule, carrier molecule or waste product. Why are the energy storage molecule and the carrier molecule important to photosynthesis?

Do Now (continued) The photosystems contain chlorophyll. Where in the chloroplast would you find them? What is the function of the photosystems? Is carbon dioxide involved in the light reactions?

Sunlight and Water

Thylakoid membranes

Oxygen waste product ATP energy molecule NADPH carrier molecule

Needed to go on to dark reactions

Pigments collect sunlight for light reactions

NO

Do Now Questions (Light Indep.) 1. The source of carbon in the light independent reaction is _________. 2. The molecule that transfers high energy electrons between the light-dependent and light-independent reactions is _____. 3. What are the reactants for the light independent reactions? 4. What are the products for the light independent reactions?

Do Now Questions 5. What is another name for the light independent reactions? 6. Why is it necessary to keep making RuBP in the cycle? 7. What happens to the ADP and NADP+? 8. What is most of the PGAL used to do in the cycle?

Answers 1. CO2

2. NADPH

3. ATP, NADPH, CO2

4. Glucose, (ADP, NADP+)

5. Calvin Cycle

6. Because RuBP is necessary to continue the cycle and make more glucose

7. Go back to light dependent reactions to “charge up”

8. To make RuBP