Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Photosynthesis Botany Light Reactions • Photosynthesis is the process by which photosynthetic organisms use light (photo) energy to drive the synthesis of organic compounds. • Occurs in plants, algae, cyanobacteria – Some bacteria do not give off oxygen as a byproduct of photosynthesis • Chemical equation is: 6CO2 + 12H2O C6H1206 + H2O + 602 • What’s the end product? – Usually stated as glucose, yet starch is the main product created, which is a combination of two monosaccharides put together. Why Care? • Green plants & algae provide almost all energy & organic matter on Earth • Provides all oxygen required for aerobic processes • It is the largest Biosynthetic process on Earth – Photosynthetic organisms remove about 200 billion metric tons of Carbon per year from the atmosphere…about 10% of total CO2 in atmosphere. – Almost all CO2 fixed by plants returns to atmosphere by microbial, plant, and animal metabolism, as well as biomass combustion (fire) Where does it happen? • In plants it happens in leaves, specifically the organelle called the chloroplast • Chloroplast is made up of several compartments or layers. – Outer envelope: outmost membrane which is permeable to most substances, and acts as the skin that holds everything in. – Inner envelope: inner membrane which is impermeable to most molecules, contains transport proteins that control movement of substances in & out of chloroplast – Thylakoids: system of internal membranes containing photosystems & electron transport chain; site of light reactions; organized into stacked & unstacked regions…stacked called grana, fluid inside known as lumen. – Stoma: a protein filled gel containing water soluble enzymes and metabolites. Site of dark or light independent reactions; known as Calvin cycle or photosynthetic carbon reduction (PCR cycle). Protein in stroma is enzyme Rubisco. Photosynthetic Process • Referred to as a two stage process – Light Reactions: discover what your book has to say about this process. – Dark Reactions: discover what your book has to say about this process. Anatomy of a Leaf Leaf Division Leaf Shapes Chapters to Study in the Book • • • • • Stems Tissues Cells Leaves Photosynthesis