PHOTOSYNTHESIS

Photosynthesis – Making Sugar from Sunlight “ Life is woven out of air by light “ Jacob Moleschott Dutch

It’s a Fundamental process –Photosynthesis

And just in case you didn’t catch all the words… …..One more time!One more time!

5 Photosynthesis Endergonic reaction (stores energy) that uses light energy, Carbon dioxide (CO 2 ), and water (H 2 O) to produce organic molecules (glucose). 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 SUN Carbon dioxide waterglucoseoxygen

So what then is the main source of energy on earth????

THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH

Light Energy Harvested by Plants & Other Photosynthetic Autotrophs 6 CO H 2 O + light energy → C 6 H 12 O 6 +6 O 2

10 Plants Autotrophs – produce their own food (glucose) Process called photosynthesis Mainly occurs in the leaves: a.stoma - pores b.mesophyll cells Stoma Mesophyll Cell Chloroplast

11 Stomata (stoma) Pores in a plant’s cuticle through which water vapor and gases (CO 2 & O 2 ) are exchanged between the plant and the atmosphere. Guard Cell Carbon Dioxide (CO 2 ) Oxygen (O 2 ) Found on the underside of leaves Stoma

12 Mesophyll Cell of Leaf Cell Wall Nucleus Chloroplast Central Vacuole Photosynthesis occurs in these cells!

Chloroplast Organelle where photosynthesis takes place. Granum Thylakoid Stroma Outer Membrane Inner Membrane Thylakoid stacks are connected together

WHY ARE PLANTS GREEN? It's not that easy bein' green Having to spend each day the color of the leaves When I think it could be nicer being red or yellow or gold Or something much more colorful like that… Kermit the Frog

Different wavelengths of visible light are seen by the human eye as different colors. WHY ARE PLANTS GREEN? Gamma rays X-raysUVInfrared Micro- waves Radio waves Visible light Wavelength (nm)

. The wavelength that is not absorbed but is reflected back equals the apparent color of an object. The feathers of male cardinals are loaded with pigments. These pigments absorb some wavelengths of light and reflect others. Reflected light

Why are plants green? Reflected light

WHY ARE PLANTS GREEN? Plant Cells have Green Chloroplasts The thylakoid membrane of the chloroplast is impregnated with photosynthetic pigments (i.e., chlorophylls, carotenoids).

Chloroplasts absorb all light energy except the green light and convert it to chemical energy Light Reflected light Absorbed light Chloroplast THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED

20 Question: During the fall, what causes the leaves to change colors?

21 Fall Colors In addition to the chlorophyll pigments, there are other pigments present During the fall, the green chlorophyll pigments are greatly reduced revealing the other pigments Carotenoids are pigments that are either red, orange, or yellow

Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water A REVIEW OF PHOTOSYNTHESIS Carbon dioxide WaterGlucoseOxygen gas PHOTOSYNTHESIS

The location and structure of chloroplasts LEAF CROSS SECTION MESOPHYLL CELL LEAF Chloroplast Mesophyll CHLOROPLAST Intermembrane space Outer membrane Inner membrane Thylakoid compartment Thylakoid Stroma Granum StromaGrana

2 Major Reactions of photosynthesis Light-dependent Reactions - use light to produce ATP and NADPH Light-independent (dark) Reactions (Calvin Cycle) use ATP and NADPH to produce sugars

A Photosynthesis Road Map Chloroplast Light Stack of thylakoids ADP + P NADP  Stroma Light reactions Calvin cycle Sugar used for  Cellular respiration  Cellulose  Starch  Other organic compounds

The Calvin cycle makes sugar from carbon dioxide –ATP and NADPH generated by the light reactions provides the energy and electrons for sugar synthesis 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

Happens in thylakoids Stacks of membranes in chloroplasts called thylakoids contain chlorophyll and membrane proteins Chlorophyll absorbs light Light Reactions

Called Calvin cycle Happens in stroma Uses ATP and NADPH from light reactions to produce stable sugars Light-independent Reactions

Review: Photosynthesis uses light energy to make food molecules

31 Energy for Life on Earth Sunlight is the ULTIMATE energy for all life on Earth Plants store energy in the chemical bonds of sugars through photosynthesis Chemical energy is released as ATP during cellular respiration