Photosynthesis
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PHOTOSYNTHESIS
Photosynthesis • Involves the Use Of Light Energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and Carbohydrates (sugars & starches)
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• Goal of photosynthesis is creating glucose
• Glucose is a monosaccharide
• One Molecule of Glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP
• Remember, C6H12O6 is not usable energy. It must be broken down during cellular respiration to be turned into ATP!
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The Photosynthesis Equation
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Pigments • In addition to water, carbon dioxide, and light energy, photosynthesis requires pigments (molecules that absorb light).
• Chlorophyll is the primary light-absorbing pigment in autotrophs.
• Chlorophyll is found inside the chloroplasts in the thylakoid membrane
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Electromagnetic Spectrum • Visible Light Contains A Mixture Of Wavelengths
• Different Wavelengths Are Seen As Different Colors
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Inside A Chloroplast
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Why do plants appear green?
Structure of the Chloroplast • Inner membrane—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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The Biochemical Reactions
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It Begins with Sunlight!
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Inside A Chloroplast
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Light Dependent Reactions
• Occurs across the thylakoid membranes
• Uses light energy • Produce Oxygen from water • Convert ADP to ATP • Also convert NADP+ into the energy carrier NADPH
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LIGHT-DEPENDENT REACTIONS
SEE A MOVIE ATP SYNTHASE IN ACTION
Light Reaction Summary Reactants: (what goes in) • H2O • Light Energy Products: (what comes out) • ATP • NADPH • Oxygen
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Light Dependent Reaction
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Calvin Cycle/ Light Independent Reactions
• Light Independent reactions (AKA Calvin Cycle) occur in the stroma
• ATP used to make carbohydrates (sugars) like glucose (stored energy) and cellulose (strengthen the plant)
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CO2 Enters the Cycle
ATP and NADPH from light dependent reactions
5-Carbon Molecules Regenerated
Sugar produced
Calvin Cycle/Light Independent Reactions
See Calvin cycle animation
Light Independent Overview • Calvin Cycle occurs in the Stroma – ATP and NADPH are used to convert 6 CO2 to glucose
– ADP and NADP+ are recycled back into the light dependent reaction
– Reactants: • CO2, ATP and NADPH
– Products: • glucose, ADP and NADP+ 20
Photosynthesis Overview
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Photosynthesis in a Nutshell: • Light Dependent Reaction
– H2O and light go in – ATP and NADPH come out and go to the Calvin Cycle (L.I.R)
– Oxygen come out as waste • Light Independent Reaction
– CO2 goes in – ATP and NADPH used for energy – Glucose (C6H12O6) comes out
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Factors that Affect Photosynthesis ____________________ Water is one of the raw materials needed, so A shortage of water can ________________ photosynthesis
AMOUNT OF WATER
Desert plants and conifers that live in dry conditions have a waxy coating on their leaves to prevent water loss.
slow or stop
Factors that Affect Photosynthesis
Photosynthetic enzymes function best between 0° C - 35° C
At temperatures above or below
this range, photosynthesis will slow or stop
Conifers in winter may carry out photosynthesis only occasionally
TEMPERATURE
Enzymes work BEST at a certain ___ and __________.
Conditions that are TOO ACIDIC or TOO HOT cause proteins to unwind or _________
pH temperature
DENATURE
Denaturing changes the shape of the enzyme making it not work
HOMEOSTASIS (keeping pH and temperature constant) is important for maintaining enzyme function.
Factors that Affect Photosynthesis
____________________ More light increases rate of photosynthesis up to a certain level until plant reaches its maximum rate of photosynthesis
LIGHT INTENSITY
THE BIG PICTURE PHOTOSYNTHESIS provides the _____________ we breathe and the __________ heterotrophs (like us) consume to survive
_____________ + ____________ _______________ + ____________
Carbon dioxide WATER Sugars Oxygen
OXYGEN sugars
Photosynthesis
includes
of
take place in takes place in uses
to produce to produce
use
Section 8-3
Concept Map
Photosynthesis
includes
of
take place in takes place in uses
to produce to produce
use
Light- dependent reactions
Calvin cycle
Thylakoid membranes Stroma NADPH ATP Energy from
sunlight
ATP NADPH O2 Chloroplasts High-energy sugars
Section 8-3
Concept Map