QOD - _______ is a membrane system found within the chloroplast, that are a flat, disc shaped structure.

Photosynthesis Chapter 9 Section 2 Chapter 9 Section 2

THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH

Harvesting Light Energy Chloroplasts – organelle responsible for converting light energy into chemical energy (glucose)

Structure of Chloroplast Parts: 1. Outer membrane - permeable 2. Inner membrane – selectively permeable 3. Stroma – small area inside the inner membrane 4. Thylakoid – flat, discs that contain pigments 5. Granum – Stack of thylakoids 6. Thylakoid membrane – structure that is folded to create thylakoids 7. Pigments – substance the absorbs the light energy and begins the process of photosynthesis

Pigments –Chlorophyll – reflects green and yellow (absorbs blues and reds) Chlorophyll a – Chlorophyll b – –Carotenoids – reflect oranges, yellows and reds (absorbs blue and green) Xanthrophyll – yellow Carotene - orange

Why are plants green? Reflected light Transmitted light

? When fall arrives, the leaves on trees turn red/orange/yellow, why is this? Which pigments are visible?

Now where Energy from the sun is absorbed by the pigments and then transferred to electrons at the reaction center. –E–Electrons becoming “excited” Gains energy and move to a higher energy level

Excited state ee Heat Light Photon Light (fluorescence) Chlorophyll molecule Ground state 2 (a) Absorption of a energy - sunlight Excitation of chlorophyll in a chloroplast ee

Photosynthesis Consists of two phases –Light dependent phase (light is required) – converts solar energy into chemical energy –Light Independent (Calvin Cycle) (does not required light to occur) converts carbon dioxide and water to glucose

Light Dependent Phase 2 parts –First part creates ATP –Second part created NADPH (electron carrying molecule) Play

QOD – The sun’s energy is transferred to _______________ in the reaction centers.

Light Dependent Phase –Occurs in the thylakoid membrane

M a k i n g A T P Pigment H 2 O  ½ O 2 + H 2 2e- Electron Transport Chain ATP L i g h t I n d e p e n d e n t C y c l e ( C a l v i n C y c l e ) To Part 2 making NADPH ATP Synthase H+

Hydrolysis Breaking down of water into hydrogen and oxygen

Pigment 2 e- NADP+ NADPH e 2e- + Light Independent Cycle (Calvin Cycle) Electron Transport Chain M a k i n g N A D P H H+ From Part I

NADPH High energy electron carrying that takes that energy to the Light Independent cycle to make glucose

Making Sugar The high energy carrying molecules, ATP and NADPH combine with the carbon from carbon dioxide to make Glucose. Light Independent Cycle (Calvin Cycle) – occurs in stroma Play

RuBP (5 carbon) CO 2 2 Pgal (3 carbon) Rubisco – enzyme that attaches the carbon 6 carbon structure created is not stable and immediately breaks down into 2, 3 carbon structures 2, 3 carbon Goes through a series of step to be modified – uses ATP and NADPH 2 ATP 2 ADP 2 NADPH 2 NADP+ PGAL goes through a series of reaction to become a 5 carbon structure 1 Pgal drops down ever three rotations. This will later become glucose after six rotations ATP ADP S t e p 1 : C a r b o n F i x a t i o n Step 2: Transferring Energy Step 3: Making Sugar RuBP (5 carbon) Step 4: Recycling ATP & NADPH enter from the light dependent cycle. Cycle starts over

Light Independent (Calvin Cycle) –Occurs in the stroma of the chloroplast

The Calvin cycle makes sugar from carbon dioxide –ATP generated by the light reactions provides the energy for sugar synthesis –The NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose Light Chloroplast Light reactions Calvin cycle NADP  ADP + P The light reactions convert solar energy to chemical energy –Produce ATP & NADPH AN OVERVIEW OF PHOTOSYNTHESIS

Factors There are 3 environmental factors that affect photosynthesis –Levels of carbon dioxide –Temperature –Light intensity

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