Photosynthesis Acquiring Energy From Light
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Transcript of Photosynthesis Acquiring Energy From Light
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PhotosynthesisAcquiring Energy From Light
•Photosynthesis is a two stage process by which Light, Water and Carbon dioxide are used to make high energy compounds Glucose (carbohydrates).
PHOTOSYNTHESIS:Chemical equation:Reactants (needed) Products (what is produced)
12H2O +6CO2 C6H12O6 + 6O2 + 6H2OSimplified: 6H2O + 6CO2 [C6H12O6] + 6O2
sunlight energy-
What is Photosynthesis? Click me
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Light- Dependent Reactions(photophosphorylation)
Light- Independent Reactions(Calvin Cycle)
Light
H20
CO2
O2
C6H12 O6
Light energy Chemical energy SUGARS SUN ATP, NADPH (C6H1206)
ATP, NADPH
“chemical energy”
“chemical energy”
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Chloroplast
Light
3O2
Sugars
CO2
Light-Dependent Reactions
CalvinCycle
NADPH
ATP
ADP + PNADP+
Chloroplast
6H2O + 6CO2 ---sunlight energy-- C6H12O6 + 6O2
Figure 8-7 Photosynthesis: An Overview
Light-Independent Reactions
Calvin Cycle
Light Dependent Reactions
NADPH+
ADP+P
ATP
NADPH
6H2O
Light
6CO2
C6H12O6
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Where Do These Reactions Take Place?
click me
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Chloroplast
Thylakoid membranes
Occurs in the chloroplast of plant and other autotrophs
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Photosynthesis starts in the (thylakoid membrane system) of the chloroplasts
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Light Dependent Reaction
The Making of Chemical Energy: PHOTOPHOSPHORYLATION
Light energy is used to split water molecules (PHOTO)6 Water molecules are split into atoms of Hydrogen and atoms of Oxygen Step 1-photolysis (click me)6 H2O 12 H and 6 O2Oxygen (O2) is by product in this reaction
Step 2-phosphorylation
H+ (hydrogen ions) from water are used to generate
“Chemical energy” in the form of ATP and NADPH
ADP ATP NADP+ + HNADPH
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HydrogenIon Movement
Photosystem II
InnerThylakoidSpace
ThylakoidMembrane
Stroma
ATP synthase
Electron Transport Chain Photosystem I ATP Formation
Chloroplast
Section 8-3
Figure 8-10 Light-Dependent Reactions
The products of the light dependent reaction:Oxygen, ATP
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The Role of Chlorophyll click me
• Light trapping pigment Chlorophyll is required for photosynthesis
• Chlorophyll absorbs all light energy EXCEPT GREEN, green wavelengths are reflected, this is why leaves are perceived as green in color.
• Fall colors of leaves result from the absence of chlorophyll and the presence of other pigments which reflect their respective colors
• Ex. Carotene (reflects orange and red wavelengths of light).
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Absorption of Light byChlorophyll a and Chlorophyll b
V B G YO R
Chlorophyll b
Chlorophyll a
Section 8-2
Figure 8-5 Chlorophyll Light Absorption
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Light Independent reactions(Calvin Cycle)
LIGHT INDEPENDENT REACTIONS: Also known as “Calvin cycle” and "Carbon Fixation "
-does not depend on sunlight for energy and proceeds in the absence of sunlightThe energy made in the light dependent reaction in the form of (ATP, NADP+H) reaction are “spent” to convert carbon compounds found in the plant cells into sugars like (glucose) C6H12O6 a carbohydrate end product.
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Video 5CARBON FIXATION
The first step involves CO2 (carbon dioxide) combining
with RUBP- a 5 carbon compound found in plants
ChloropIast
CO2 Enters the Cycle
Energy Input
5-CarbonMoleculesRegenerated
Sugars and other compounds
6-Carbon SugarProduced
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The Light-Independent Reactions “Carbon Fixation”Step 1) Carbon dioxide from the air is combined with a 5-carbon sugar RuBP (Ribulose biphosphate)
3 CO2 + 3 RuBP------> 6 PGA (each cycle)
This forms a 6-carbon molecule PGA (Phosphoglycerate)
Step 2) 12 ATP are "spent" to convert PGA to PGAL a 3-carbon molecule and 12 H (hydrogen) are added to the molecule
6 PGA + [Chemical Energy] 12 PGAL [12 ATP12 ADP]
[12 NADP+H 12 NADP]
=Phosphoglyeraldehyde
“spending energy”
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Step 3) 6 additional ATP are "spent" to convert PGAL into sugar and recycle RuBP
PGAL + PGAL--------> C6H12O6 + RuBP [6 ATP---> 6ADP] “energy spent”
Summary:18 ATP made in the light dependent reactions are "spent" in the light independent reaction to make one molecule of PGALTwo cycles of the Calvin Cycle = 2PGALTotal cost is 36 ATP+2PGAL=1glucose (sugar)
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Photosynthesis
includes
of
take place intakes place in uses
to produce to produce
use
Light-dependentreactions
Calvin cycle
Thylakoidmembranes Stroma CO2ATP
NADPH
Energy fromsunlight
ATP NADPH O2 Chloroplasts High-energysugars
Section 8-3
Concept Map
H2O