PHOTOSYNTHESIS Solar energy –Very available –Hard to store Collected by plants Converted to chemical energy –Easier to store Requires chlorophyll ( chloroplast ) Energy now stored as carbohydrates * Plants store energy AND plants spend energy*

Properties of Light ROYGBIV –White light contains all the colors (wavelenghts) Reflected –You only see what’s not absorbed Light is both energy and particle (photon) Wavelength = energy Pigments = chemical compounds that reflect color. Chlorophyll is pigment/chemical in chloroplast

Plant Structures Roots –Often underground –Collect water –Rarely green – need sugar supply !? Stems –Usually above ground –Lots of cellulose ( herbaceous vs. wood) –Support … hold up to sun. –May be green Leaves –GREEN!! Contain chlorophyll, in their chloroplasts –Collect sunlight and collect CO 2, also release O 2 –Do photosynthesis…. Make organic compounds like sugar Flowers –Reproductive structures that contain eggs and pollen –Will eventually becomes seeds and/or a fruit with seeds. –May be colored but pigments are not usually chlorophyll

Leaf structure

Review of chemical molecules

Leaf vocabulary Cuticle: thin layer of clear, waxy cells on top, waterproof, Mesophyll: rectangular cells where photosynthesis occurs Palisade mesophyll: arranged in columns, lots of photo, very green Spongy mesophyll: scattered, air pockets, lighter green Chloroplast: organelle that performs photosynthesis –Thylakoid membrane – inner membranes, packets, have chlorophyll –Stroma – liquid inside chloroplast Water vacuole: holds water, chloroplasts surround this Stoma/ stomata: opening on underside of leaf, O 2 out and CO 2 in, open and close in response to the weather Vascular tissue – carries fluids, just like our vascular tissue (veins) –Xylem : carries water and water soluble substances, from root to leaves –Phloem: carries “food”, sugars and organic compounds, from leaves to storage ( root or fruit)

Water in the roots, up xylem Water split Requires solar energy Some energy now stored as chemicals called NADPH and ATP Oxygen is released, hydrogen is used in chemicals CO 2 comes in through stomata as a supply NADPH and ATP energy used to link C-C This creates organic compounds like glucose

History and Discovery Jan von Helmont –Mass of seedling, soil and water didn’t equal mass of tree …. What is rest of mass ? Joseph Priestley –Discoverer of oxygen, mint plus candle in a bell jar would stay lit Jan Ingenhousz –Priestley’s mint experiment only worked in the sunlight Melvin Calvin –Used radioactive carbon to trace the dark reactions in photosynthesis… now called the Calvin Cycle

Light reactions IN –Water –Light OUT –NADPH and ATP –Oxygen Reactions –Water is split, electrons are moved, H is bonded –Electrons are moved along Electron Transport Chain (ETC) Location –Photocenters on thylakoid membrane of chloroplast –Requires chlorophyll Result –Water is split –H is bonded –Oxygen is released – (solar) ENERGY IS STORED (as a chemical bond)

Dark reactions – Calvin Cycle In –NADPH and ATP from light reactions –CO 2 Out –Carbohydrates (sugar) and organic compounds Reactions –CO2 is added to organic acids to create compounds –Costs NADPH and ATP –C to C bonds are being formed Location –Stroma (fluid) in the chloroplast Result –Plants are producers …. Of organic compounds like carbohydrates –Organic acids are regenerated as part of the cycle.

** YOU MUST KNOW THIS ** Sunlight 6 CO H 2 O C 6 H 12 O O 2 chlorophyll reactants, products, coefficients and subscripts

Plants (Autotrophs) are able to make lots of compounds. Organic compounds with rings and chains of carbon. They include GLUCOSE, but also amino acids, proteins, fatty acids, lipids, other carbohydrates and the nucleic acis. sunlight 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 chlorophyll roots leaves phloem stomata Reactants “react” and Products are “produced”

Glucose and “sugars”

Other Carbohydrates

Cellulose and lignin