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 CO2, also release O2

– 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, O2 out and

CO2 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• CO2 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– CO2

• 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 CO2 + 6 H2O C6H12O6 + 6 O2

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

6CO2 + 6H2O C6H12O6 + 6O2

chlorophyll

roots leaves phloem

stomata stomata

Reactants “react” and Products are “produced”

Glucose and “sugars”

Other Carbohydrates

Cellulose and lignin