Presentation on theme: "January 8, 2014! Welcome Back! Bellringer: Photosynthesis … Pass back exams Go over EVERY question Diagnose Wrong Answers Start Photosynthesis Notes HW:"— Presentation transcript:
January 8, 2014! Welcome Back! Bellringer: Photosynthesis … Pass back exams Go over EVERY question Diagnose Wrong Answers Start Photosynthesis Notes HW: Draw and Define the parts of the Chloroplast (pg. 111)
1/9/14 Bellringer: 6…5…4… Check off HW Photosynthesis Notes HW: Read 114-116 (or at least the chapter summary)
6…5…4 There are 6 schooldays until finals (& Final Grades). Create and Fill out the following table
Photosynthesis What does it mean to photosynthesize? Who Photosynthesizes? Name the reactants and products of photosynthesis.
Photosynthesis Photosynthesis: When light energy is used by producers/autotrophs to make sugars and other food molecules ~75% performed in the ocean Temperature, light intensity, water and carbon dioxide supply affect the efficiency
Photosynthesis Equation 6CO 2 + 6H 2 O Energy from sunlight (in chlorophyll) C 6 H 12 O 6 + 6O 2
Photosynthesis Reactants/Products Reactants: CO 2 : Let into the leaf through pores called stomata H 2 O: Taken in through the roots Catalyst: Chlorophyll: Pigment in chloroplast that catches sunlight Products: O 2 : Used by plants/animals for cellular respiration Glucose: Used by the plant (or by an animal that eats the plant!) for energy (C 6 H 12 O 6 )
Oxidation-Reduction Reactions Reactions that give or take electrons are called “oxidative-reduction reactions” or Redox rxns Oxidation = Molecules lose electrons or hydrogen Reduction: Molecules gain electrons or hydrogen In organisms, each electron travels with a proton (an H atom)…
Cont’d Photosynthesis IS a Redox reaction H 2 O is oxidized CO 2 is reduced Electrons gain energy
Why do we see certain colors? Why do we see this red sweatshirt as red? Answer: When all colors (ROYGBIV) hit it, all colors are absorbed but red, which is reflected back to our eyes!
Why do white things LOOK white? Because all the colors (ROYGBIV) are hitting the object, and all the colors are reflecting back into your eyes
Why do black things LOOK black? Because all the colors (ROYGBIV) are hitting the object, and all the colors are being absorbed
Pigments (start writing notes again) Pigments: The natural coloring matter of organisms Several pigments are built into the thylakoids of chloroplasts These absorb some wavelengths of light; reflect or transmit others Chlorophyll a: Absorbs blue-violet and red light, reflects green light Participates directly in the light reactions
Cont’d Chlorophyll b: Absorbs blue and orange light, reflects yellow- green Gives absorbed energy to chlorophyll a Carotenoids: Yellow-orange pigments Pass energy to chlorophyll a or protect it by dissipating excessive light energy Xanthophylls: Yellow pigments
Stage 1: Light Reactions The light reaction takes place in the thylakoid (disc inside the chloroplast Chloroplast Thylakoid
Stage 1: Light Reactions When photosynthesizers absorb sunlight, it boosts their electrons to higher energy levels It EXCITES them The electron now has more energy
PARTS OF THE LIGHT RXN 1) Photosystem: First part of the light reaction that gathers light. Contains the following: A. Pigment Molecules: these absorb sunlight and give their energy to Chlorophyll a B. Chlorophyll a Reaction Center: The molecule whose electron gets excited, and moves on to… C. Primary Electron Acceptor: These take the electron from the reaction center There are 2 photosystems in the light reaction Photosystem II: (P680), and Photosystem I: (P700)
Electron Transport Chain (ETC) Electron transport chain(ETC): Series of proteins in the thylakoid membrane that makes the products of the light reaction Takes the high energy electrons from the photosystems Uses the electrons’ energy is to make ATP and NADPH ATP: Made from ADP NADPH: Carries electrons to the light- independent reaction, made from NADP+
Steps of the Light Reaction 1. Light excites an electron (e-)in Photosystem II’s reaction center, and it goes to the Electron Transport Chain 2. A water molecule replaces the lost electrons 3. e- moves down ETC (electron transport chain),and this makes ATP 4. Light excites an electron in Photosystem I’s reaction center, and it goes to the second Electron Transport Chain 5. e- moves down ETC, which makes NADPH
LIGHT RXN SUMMARY What do plants enter the light reaction with? Energy from sunlight and pigments to absorb it What do plants leave the light reaction with? ATP and NADPH WHAT DO WE HAVE LEFT TO DO? Actually build the glucose molecule!!!
The Light-Independent Reaction/Dark Reaction/Calvin Cycle 2nd part of Photosynthesis, and occurs in the stroma Uses carbon atoms from CO 2 to make the backbone of a sugar molecule (glucose) Glucose is made ATP is used to get the energy for this (recycling) Molecules of NADPH donate electrons and become NADP+ (recycling)
THE OVERALL LIGHT- INDEPENDENT REACTION!!! What do plants enter with? ATP, NADPH, and CO 2 What do plants leave the light reaction with? Glucose
Bellringer What is the equation for photosynthesis? What products have we made thus far? Where does the light reaction take place?
Bellringer What part of the chloroplast does the light reaction take place in In the Light Reaction of photosynthesis, what happens in the photosystems? What happens in the electron transport chains?