Transcript PHOTOSYNTHESIS

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 l
• 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
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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
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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)
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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
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Water is split, electrons are moved, H is bonded
Electrons are moved along
Electron Transport Chain (ETC)
Location
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NADPH and ATP
Oxygen
Reactions
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Water
Light
Photocenters on thylakoid membrane of chloroplast
Requires chlorophyll
Result
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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
stomata
Reactants “react”
phloem
stomata
and
Products are “produced”
Glucose and “sugars”
Other Carbohydrates
Cellulose and lignin