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MONDAY BELLRINGER

GET OUT YOUR

COMPOSITION NOTEBOOK

TURN TO YOUR FIRST BLANK PAGE TITLE IT

PHOTOSYNTHESIS.

Make sure you are in the proper seat in order to be

counted present!!

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HISTORY OF PHOTOSYNTHESIS &

PLANT PIGMENTS

INVESTIGATING PHOTOSYNTHESIS

•Many Scientists Have Contributed To Understanding Photosynthesis

•Early Research Focused On The Overall Process

•Later Researchers Investigated The Detailed Chemical Pathways 3

VAN HELMONT’S EXPERIMENT 1643

• Planted a seed into A pre-measured amount of soil and watered for 5 years

• Weighed Plant & Soil. Plant Was 75 kg, Soil The Same.

• Concluded Mass Came From Water 4

PRIESTLEY’S EXPERIMENT 1771

• Burned Candle In Bell Jar Until It Went Out.

• Placed Sprig Of Mint In Bell Jar For A Few Days.

• Candle Could Be Relit And Burn.

• Concluded Plants Released

Substance (O2) Necessary

For burning. 5

INGENHOUSZ’S EXPERIMENT 1779

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Repeated Priestly experiment with & without sunlight

RESULTS OF INGENHOUSZ’S EXPERIMENT

•Showed That Priestley’s Results Only Occurred In The Presence Of Sunlight.

•Light Was Necessary For Plants To Produce The “Burning Gas” or oxygen

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JULIUS ROBERT MAYER 1845

Proposed That Plants can Convert Light Energy Into Chemical Energy

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SAMUEL RUBEN & MARTIN KAMEN1941

Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water

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KAMEN

RUBIN

MELVIN CALVIN 1948

•First to trace the path that

carbon (CO2) takes in

forming Glucose

•Does NOT require sunlight

•Called the Calvin Cycle or Light Independent Reaction

•Also known as the Dark Reaction

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RUDOLPH MARCUS 1992

•Studied the Light Independent Reactions

•First to describe the Electron transport Chain

THE PHOTOSYNTHESIS EQUATION

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PIGMENTS

• In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments

•Chlorophyll is the primary light-absorbing pigment in autotrophs

•Chlorophyll is found inside chloroplasts

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LIGHT AND PIGMENTS

•Energy From The Sun Enters Earth’s Biosphere As Photons

•Photon = Light Energy Unit•Light Contains A Mixture Of Wavelengths

•Different Wavelengths Have Different Colors

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LIGHT & PIGMENTS

•Different pigments absorb different wavelengths of light

•Photons of light “excite” electrons in the plant’s pigments

•Excited electrons carry the absorbed energy

• Excited electrons move to HIGHER energy levels 15

CHLOROPHYLL

There are 2 main types of chlorophyll molecules:

Chlorophyll a

Chlorophyll b

A third type, chlorophyll c, is found in dinoflagellates 16

Magnesium atom at the center of chlorophyll

CHLOROPHYLL A AND B

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CHLOROPHYLL A

•Found in all plants, algae, & cyanobacteria

•Makes photosynthesis possible

•Participates directly in the Light Reactions

•Can accept energy from chlorophyll b

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CHLOROPHYLL B

• Chlorophyll b is an accessory pigment

• Chlorophyll b acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a

• Like chlorophyll a, it absorbs red & blue light and REFLECTS GREEN

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WHAT THEN IS PHOTOSYNTEHSIS?

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WHAT IS PHOTOSYNTHESIS ?

• Involves the use of light Energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches

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PHOTOSYNTHESISOVERVIEW

•AUTOTROPHS

•Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food.

Make their own food using the sunlight

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PHOTOSYNTHESISOVERVIEW

•HETEROTROPHS

•Are organisms that can NOT make their own food

•They can NOT directly use the sun’s energy

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PHOTOSYNTHESISOVERVIEW

• Energy

• Energy takes many forms such as light, heat, electrical, chemical and mechanical

• Energy can be stored in chemical bonds and then released later on

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PHOTOSYNTHESISOVERVIEW

Cells Use BIOCHEMICAL energy

Cells use ATP for:

• Active transport

•Movement

• Photosynthesis

• Protein Synthesis

• Cellular respiration

• All other cellular reactions

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PHOTOSYNTHESISOVERVIEW

• ATP – Cellular Energy

• Adenosine Triphosphate

•Contains two, high-energy phosphate bonds

• Also contains the nitrogen base adenine and a ribose sugar

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PHOTOSYNTHESISOVERVIEW

• ADP – Adenosine Diphosphate

• ATP releases energy, a free phosphate, & ADP when cells take energy from ATP

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IMPORTANCE OF ATP

Principal Compound Used To Store Energy In Living Organisms

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IMPORTANCE OF ATP

•ATP is constantly being used and remade by cells

•ATP provides all of the energy for cell activities

•The high energy phosphate bonds can be BROKEN to release energy

•The process of releasing ATP’s energy & reforming the molecule is called phosphorylation

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RELEASING ENERGY FROM ATP

•Adding A Phosphate Group To ADP stores Energy in ATP

•Removing A Phosphate Group From ATP Releases Energy & forms ADP

Lose

Gain

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ONE MORE THING ON ATP

•Cells Have Enough ATP To Last For A Few Seconds

•ATP must constantly be made

•ATP Transfers Energy Very Well

•ATP Is NOT Good At Energy Storage

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PHOTOSYNTHESIS OVERVIEW

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THE BIOCHEMICAL REACTIONS

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IT BEGINS WITH SUNLIGHT!

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PHOTOAUTOTROPHS ABSORB LIGHT ENERGY

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INSIDE A CHLOROPLAST

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STRUCTURE OF THE CHLOROPLAST

•Double membrane organelle•Outer membrane smooth•Inner membrane forms stacks of connected sacs called thylakoids•Thylakoid stack is called the granum (grana-plural)•Gel-like material around grana called stroma

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FUNCTION OF THE STROMA

•Light Independent reactions occur here

•ATP used to make carbohydrates like glucose

•Location of the Calvin Cycle

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THYLAKOID MEMBRANES

•Light Dependent reactions occur here•Photosystems are made up of clusters of chlorophyll molecules•Photosystems are embedded in the thylakoid membranes•The two photosystems are:• Photosystem I• Photosystem II

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PHOTOSYNTHESIS OVERVIEW

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ENERGY CARRIERS

•Nicotinamide Adenine Dinucleotide Phosphate (NADP+)

•NADP+ = Reduced Form

•Picks Up 2 high-energy electrons and H+ from the Light Reaction to form NADPH

•NADPH carries energy to be passed on to another molecule

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NADPH

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•Occurs across the thylakoid membranes

•Uses light energy

•Produce Oxygen from water

•Convert ADP to ATP

•Also convert NADP+ into the energy carrier NADPH

LIGHT DEPENDENT REACTIONS

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LIGHT DEPENDENT REACTION

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LIGHT DEPENDENT REACTION

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PHOTOSYSTEM I

•Discovered First

•Active in the final stage of the Light Dependent Reaction

•Made of 300 molecules of Chlorophyll

•Almost completely chlorophyll a

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PHOTOSYSTEM I

High-energy electrons are moved to Photosystem I through the Electron Transport Chain

Energy is used to transport H+ from stroma to inner thylakoid membrane

NADP+ converted to NADPH when it picks up 2 electrons & H+

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PHOTOSYSTEM II

•Discovered Second

•Active in the beginning stage Of the Light Dependent Reaction

•Contains about equal amounts of chlorophyll a and chlorophyll b

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PHOTOSYNTHESIS BEGINS

1. Photosystem II absorbs light energy

2. Electrons are energized and passed to the Electron Transport Chain

3. Lost electrons are replaced from the splitting of water into 2H+, free electrons, and Oxygen

4. 2 H+ pumped across thylakoid membrane

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PHOSPHORYLATION

Enzyme in thylakoid membrane called ATP Synthase

As H+ ions passed through thylakoid membrane, enzyme binds them to ADP

Forms ATP for cellular

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LIGHT REACTION SUMMARY

Reactants:

•H2O

•Light Energy

Energy Products:

•ATP

•NADPH

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LIGHT INDEPENDENT REACTION

•ATP & NADPH from light reactions used as energy

•Atmospheric C02 is used to make

sugars like glucose and fructose

•Six-carbon Sugars made during the Calvin Cycle

•Occurs in the stroma

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THE CALVIN CYCLE

•Two turns of the Calvin Cycle are required to make one molecule of glucose

•3-CO2 molecules enter the cycle to form several intermediate compounds (PGA)•A 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycle

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THE CALVIN CYCLE

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FACTORS AFFECTING THE RATE OF PHOTOSYNTHESIS

•Amount of available water

•Temperature

•Amount of available light energy

WORKSHEET TIME READING

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