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1
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!!
2
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
6
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
7
JULIUS ROBERT MAYER 1845
Proposed That Plants can Convert Light Energy Into Chemical Energy
8
SAMUEL RUBEN & MARTIN KAMEN1941
Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water
9
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
10
RUDOLPH MARCUS 1992
•Studied the Light Independent Reactions
•First to describe the Electron transport Chain
THE PHOTOSYNTHESIS EQUATION
12
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
13
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
14
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
17
CHLOROPHYLL A
•Found in all plants, algae, & cyanobacteria
•Makes photosynthesis possible
•Participates directly in the Light Reactions
•Can accept energy from chlorophyll b
18
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
19
20
WHAT THEN IS PHOTOSYNTEHSIS?
21
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
22
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
23
PHOTOSYNTHESISOVERVIEW
•HETEROTROPHS
•Are organisms that can NOT make their own food
•They can NOT directly use the sun’s energy
24
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
25
PHOTOSYNTHESISOVERVIEW
Cells Use BIOCHEMICAL energy
Cells use ATP for:
• Active transport
•Movement
• Photosynthesis
• Protein Synthesis
• Cellular respiration
• All other cellular reactions
26
PHOTOSYNTHESISOVERVIEW
• ATP – Cellular Energy
• Adenosine Triphosphate
•Contains two, high-energy phosphate bonds
• Also contains the nitrogen base adenine and a ribose sugar
27
PHOTOSYNTHESISOVERVIEW
• ADP – Adenosine Diphosphate
• ATP releases energy, a free phosphate, & ADP when cells take energy from ATP
28
IMPORTANCE OF ATP
Principal Compound Used To Store Energy In Living Organisms
29
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
30
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
31
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
32
PHOTOSYNTHESIS OVERVIEW
33
THE BIOCHEMICAL REACTIONS
34
IT BEGINS WITH SUNLIGHT!
35
PHOTOAUTOTROPHS ABSORB LIGHT ENERGY
36
INSIDE A CHLOROPLAST
37
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
38
FUNCTION OF THE STROMA
•Light Independent reactions occur here
•ATP used to make carbohydrates like glucose
•Location of the Calvin Cycle
39
40
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
41
PHOTOSYNTHESIS OVERVIEW
42
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
43
NADPH
44
•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
45
LIGHT DEPENDENT REACTION
46
LIGHT DEPENDENT REACTION
47
PHOTOSYSTEM I
•Discovered First
•Active in the final stage of the Light Dependent Reaction
•Made of 300 molecules of Chlorophyll
•Almost completely chlorophyll a
48
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+
49
PHOTOSYSTEM II
•Discovered Second
•Active in the beginning stage Of the Light Dependent Reaction
•Contains about equal amounts of chlorophyll a and chlorophyll b
50
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
51
PHOSPHORYLATION
Enzyme in thylakoid membrane called ATP Synthase
As H+ ions passed through thylakoid membrane, enzyme binds them to ADP
Forms ATP for cellular
52
LIGHT REACTION SUMMARY
Reactants:
•H2O
•Light Energy
Energy Products:
•ATP
•NADPH
53
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
54
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
55
THE CALVIN CYCLE
56
FACTORS AFFECTING THE RATE OF PHOTOSYNTHESIS
•Amount of available water
•Temperature
•Amount of available light energy
WORKSHEET TIME READING
57