Video Where do trees get their mass?-Veritasium (Resources Page)

Where Does Photosynthesis Occur? Leaf Cross Section Mesophyll CO2 O2 Vein Leaf Stoma Mesophyll Cell Chloroplast Thylakoid Thylakoid space Stroma Granum Inner and outer membranes Key Terms Mesophyll- Green tissue in the middle of the leaf that contains cells with concentrated chlorophyll Stomata- Tiny holes on the underside of the leaf that allow CO2 to enter and O2 to exit

Where Does Photosynthesis Occur? Leaf Cross Section Mesophyll CO2 O2 Vein Leaf Stoma Mesophyll Cell Chloroplast

Where Does Photosynthesis Occur? Chloroplast Thylakoid Thylakoid space Stroma Granum Inner and outer membranes

Chloroplast Key Terms Thylakoid- membranous sac which encloses the thylakoid space and houses much of the machinery that converts light energy to chemical energy. Grana- Stacks of thylakoids Stroma- thick liquid within the chloroplast that the thylakoids are suspended in.

Photosynthesis Equation Becomes reduced Becomes oxidized

Overview of Photosynthesis

Overview of Photosynthesis

Overview of Photosynthesis

Pigments Absorb Light Energy Sunlight contains energy called electromagnetic energy or electromagnetic radiation. The visible part is a very small part of the spectrum.

Pigments Absorb Light Energy Chlorophyll is one of the pigments that absorb light energy in plants. Built into the Thylakoid membrane Absorb some colors and other colors are transmitted or reflected.

Different Pigments in Plants Chlorophyll a Participates directly in light reactions. Absorbs mainly blue-violet and red light. Reflects green light. Chlorophyll b Broadens the range of light absorbed and passes energy to Chlorophyll a to be used. Absorbs mainly blue and orange light. Reflects yellow-green light.

Different Pigments in Plants Carotenoids- yellow/orange Broadens the spectrum of light that can be absorbed and passed to Chlorophyll a to be used in photosynthesis. Used in photoprotection by absorbing dissipated light that could harm chlorophyll or interact with oxygen and damage cells. Break down slower than chlorophyll.

Photosystems In the thylakoid membrane, chlorophyll and other pigments and proteins are organized into clusters called photosystems Photosystems consists of a number of light-harvesting complexes that surround a reaction-center complex.

Photosystems Pigment molecules absorb light and transfer energy until it reaches the reaction-center complex Then a special pair of Chlorophyll a molecules transfer an excited electron to the Primary Electron Acceptor

Photosystems This transfer of energy is the first step in converting light energy into chemical energy in the light reactions. Two types of photosystems work together in the light reactions. Photosystem II Photosystem I Connected by an Electron Transport Chain Differ by the type of light absorbed

Photosystems In the light reactions, light energy is transformed into the chemical energy of ATP and NADPH. To accomplish this, electrons are removed from water, passed from photosystem II to photosystem I, and accepted by NADP+, reducing it to NADPH. Between the two photosystems, the electrons move down an electron transport chain and provide energy for the synthesis of ATP.

Photosystems

Light Reaction Products The products of the light reactions are NADPH, ATP, and oxygen.

Photosynthesis

Calvin Cycle Called dark reactions or light independent reactions Produces sugars in the cell by using: CO2 from air ATP and NADPH from Light Reactions Produces an energy rich three carbon sugar called Glyceraldehyde-3-Phosphate (G3P) G3P can then be used to make glucose and other molecules.

Calvin Cycle Glucose

Connection to Light Reactions

Steps of the Calvin Cycle The steps of the Calvin cycle include: carbon fixation, reduction, release of G3P, and regeneration of the starting molecule ribulose bisphosphate (RuBP).

Step Carbon fixation Input: 3 CO2 Rubisco 3 P P 6 P RuBP 3-PGA Figure 7.10B_s1 Step Carbon fixation 1 Input: 3 CO2 Rubisco 1 3 P P 6 P RuBP 3-PGA Calvin Cycle Figure 7.10B_s1 Details of the Calvin cycle, which takes place in the stroma of a chloroplast (step 1) 26

Step Carbon fixation Input: 3 CO2 Rubisco 3 P P 6 P RuBP 3-PGA Figure 7.10B_s2 Step Carbon fixation 1 Input: 3 CO2 Rubisco 1 3 P P 6 P RuBP 3-PGA Step Reduction 2 6 ATP 6 ADP P Calvin Cycle 2 6 NADPH 6 NADP Figure 7.10B_s2 Details of the Calvin cycle, which takes place in the stroma of a chloroplast (step 2) 6 P G3P 27

Step Release of one molecule of G3P 6 NADP 6 P 5 P G3P G3P Figure 7.10B_s3 Step Carbon fixation 1 Input: 3 CO2 Rubisco 1 3 P P 6 P RuBP 3-PGA Step Reduction 2 6 ATP 6 ADP P Calvin Cycle 2 6 NADPH Step Release of one molecule of G3P 3 6 NADP Figure 7.10B_s3 Details of the Calvin cycle, which takes place in the stroma of a chloroplast (step 3) 6 P 5 P G3P G3P 3 Glucose and other compounds Output: 1 P G3P 28

Step Release of one molecule of G3P 6 NADP 6 P 5 P G3P G3P Figure 7.10B_s4 Step Carbon fixation 1 Input: 3 CO2 Rubisco 1 3 P P 6 P RuBP 3-PGA Step Reduction 2 6 ATP 3 ADP 6 ADP P Calvin Cycle 4 2 3 ATP 6 NADPH Step Release of one molecule of G3P 3 6 NADP Figure 7.10B_s4 Details of the Calvin cycle, which takes place in the stroma of a chloroplast (step 4) 6 P 5 P G3P G3P 3 Glucose and other compounds Step Regeneration of RuBP 4 Output: 1 P G3P 29

Animation Photosynthesis Animation-McGraw Hill (Resources Page) http://www.mhhe.com/biosci/bio_animations/02_MH_Photosynthesis_Web/