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Photosynthesis Acquiring Energy From Light. What is Photosynthesis? Click me. 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: - PowerPoint PPT Presentation
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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
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”
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
Where Do These Reactions Take Place?
click me
Chloroplast
Thylakoid membranes
Occurs in the chloroplast of plant and other autotrophs
Photosynthesis starts in the (thylakoid membrane system) of the chloroplasts
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
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
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).
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
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.
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
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”
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)
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
