PHOTOSYNTHESIS. Photosynthesis – Making Sugar from Sunlight “ Life is woven out of air by light...
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Transcript of PHOTOSYNTHESIS. Photosynthesis – Making Sugar from Sunlight “ Life is woven out of air by light...
PHOTOSYNTHESIS
Photosynthesis – Making Sugar from
Sunlight
“Life is woven out of air by light “
Jacob Moleschott Dutch
And just in caseyou didn’t catch all the words… …..One more time!
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Photosynthesis• Endergonic reaction (stores energy) that uses light energy , Carbon
dioxide (CO2), and water (H2O) to produce organic molecules (glucose).
6CO2 + 6H2O C6H12O6 + 6O2
SUN
Carbon dioxide
water glucose oxygen
So what then is the main source of energy on earth????
THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON
EARTH
Light Energy Harvested by Plants & Other Photosynthetic Autotrophs
6 CO2 + 6 H2O + light energy → C6H12O6 +6 O2
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Plants• Autotrophs – produce their own
food (glucose)• Process called photosynthesis• Mainly occurs in the leaves:
a. stoma - poresb. mesophyll cells
StomaMesophyllCell
Chloroplast
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Stomata (stoma)Pores in a plant’s cuticle through
which water vapor and gases (CO2 & O2) are exchanged between the plant and the atmosphere.
Guard Cell
Guard CellCarbon Dioxide
(CO2)
Oxygen (O2)
Found on the underside of leaves
Stoma
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Mesophyll Cell of Leaf
Cell Wall
Nucleus
Chloroplast
Central Vacuole
Photosynthesis occurs in these cells!
ChloroplastOrganelle where
photosynthesis takes place.
GranumThylakoid
Stroma
Outer Membrane
Inner Membrane
Thylakoid stacks are connected together
WHY ARE PLANTS GREEN?
It's not that easy bein' green Having to spend each day the color of the leaves When I think it could be nicer being red or yellow or gold Or something much more colorful like that…
Kermit the Frog
Different wavelengths of visible light are seen by the human eye as different colors.
WHY ARE PLANTS GREEN?
Gammarays
X-rays UV Infrared
Micro-waves
Radiowaves
Visible light
Wavelength (nm)
The wavelength that is not absorbed but is reflected back equals the apparent color of an object.
The feathers of male cardinals are loaded with pigments. These pigments absorb some wavelengths of light and reflect others.
Reflected light
Why are plants green?
Reflected
light
WHY ARE PLANTS GREEN?
Plant Cells have Green Chloroplasts
The thylakoid membrane of the chloroplast is impregnated with photosynthetic pigments (i.e., chlorophylls, carotenoids).
• Chloroplasts absorb all light energy except the green light and convert it to chemical energy
LightReflected
light
Absorbedlight
Chloroplast
THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED
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Question:
During the fall, what causes the leaves to
change colors?
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Fall Colors
• In addition to the chlorophyll pigments, there are other pigments present
• During the fall, the green chlorophyll pigments are greatly reduced revealing the other pigments
• Carotenoids are pigments that are either red, orange, or yellow
• Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water
A REVIEW OF PHOTOSYNTHESIS
Carbondioxide
Water Glucose Oxygengas
PHOTOSYNTHESIS
The location and structure of chloroplasts
LEAF CROSS SECTION MESOPHYLL CELL
LEAF
Chloroplast
Mesophyll
CHLOROPLAST Intermembrane space
Outermembrane
Innermembrane
ThylakoidcompartmentThylakoidStroma
Granum
StromaGrana
2 Major Reactions of photosynthesis
• Light-dependent Reactions-
• use light to produce ATP and NADPH
• Light-independent (dark) Reactions (Calvin Cycle)
• use ATP and NADPH to produce sugars
A Photosynthesis Road Map
Chloroplast
Light
Stack ofthylakoids ADP
+ P
NADP
Stroma
Lightreactions
Calvincycle
Sugar used for
Cellular respiration Cellulose Starch
Other organic compounds
• The Calvin cycle makes sugar from carbon dioxide– ATP and NADPH
generated by the light reactions provides the energy and electrons for sugar synthesis
LightChloroplast
Lightreactions
Calvincycle
NADP
ADP+ P
• The light reactions convert solar energy to chemical energy– Produce ATP &
NADPH
AN OVERVIEW OF PHOTOSYNTHESIS
• Happens in thylakoids• Stacks of membranes in chloroplasts called thylakoids contain chlorophyll and membrane proteins• Chlorophyll absorbs light
Light Reactions
• Called Calvin cycle• Happens in stroma• Uses ATP and NADPH from light reactions to produce stable sugars
Light-independent Reactions
Review: Photosynthesis uses light energy to make food molecules
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Energy for Life on Earth• Sunlight is the ULTIMATE
energy for all life on Earth• Plants store energy in the
chemical bonds of sugars through photosynthesis
• Chemical energy is released as ATP during cellular respiration
