PHOTOSYNTHESIS - CHS Science Department Mrs. Davis€¦ · Understanding Photosynthesis Jan...
Transcript of PHOTOSYNTHESIS - CHS Science Department Mrs. Davis€¦ · Understanding Photosynthesis Jan...
PHOTOSYNTHESISMolecular Biology
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______________________________________________Chemical Energy and ATP
ADP ATP
Energy
Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)
Partially charged battery
Fully charged battery
• Adenosine Triphosphate (ATP) is a short term energy storage molecule.
______________________________________________Chemical Energy and ATP
Examples of how ATP is used: – active transport (Na+ and K+ pumps) – movement of motor proteins – protein synthesis – photosynthesis
______________________________________________Energy Flow
Autotrophs - convert light energy from the sun into stored chemical energy (sugar)
______________________________________________What are plants made of?
• Plants are mainly carbohydrates. sugar C H O 6 12 62
• Where does the H2O come from?
• Where does the Carbon come from?
=
______________________________________________Photosynthesis
Photo = Light
Photosynthesis a process that uses the energy of sunlight to combine water and carbon dioxide into sugar and oxygen.
Synthesize = Combine together.
______________________________________________Photosynthesis
Light Energy
Chloroplast
CO2 + H2O Sugars + O2
______________________________________________Understanding Photosynthesis
Jan van Helmont Experiment (1643) – weighed a seedling and soil – watered for 5 years
Results – tree gained 75 kg – mass of soil was unchanged.
Conclusion – tree mass must have come from the water.
______________________________________________Understanding Photosynthesis
Joseph Priestly Experiment (1771) – candle under a bell jar – candle and mint plant
Results – candle with plant burned longer
Conclusion – Plants release oxygen
______________________________________________Understanding Photosynthesis
Jan Ingenhousz Experiment (1779) – aquatic plants in light – aquatic plants in dark
Results – aquatic plants in light produce bubbles
Conclusion – plants need sunlight to produce oxygen.
______________________________________________Understanding Photosynthesis
Theodor Engelmann Experiment (1882) – used prism to divide light into component colors – exposed photosynthetic algae to the light
Results – oxygen-requiring bacteria concentrated where
oxygen levels were highest Conclusion – red and violet colors of light
drive photosynthesis
______________________________________________Light & Pigments
Absorption of Light by Chlorophyll
Chlorophyll b
Chlorophyll a
• Chlorophyll a most common pigment in plants, protists, and bacteria.
Green Reflected
Red & Violet Absorbed
______________________________________________Chloroplast
• The chloroplast is the organelle that specializes in photosynthesis. – DNA – Ribosomes – Thylakoid (folded inner membrane) chloroplasts
in plant cell
cross sectionof leaf
chloroplasts contain
chlorophyll
______________________________________________Inside a Chloroplast
• Chloroplast structure – stroma
• fluid-filled interior – thylakoid
• contains chlorophyll • light reactions
– grana • stacks of thylakoids
______________________________________________Photosynthesis
light energy
water carbon dioxide glucose oxygen
______________________________________________Photosynthesis
• Photosynthesis occurs in two stages. – light-dependent reactions
• driven by light • occurs at the thylakoid membrane
– light-independent reactions • light does not power these reactions • occurs in the stroma
______________________________________________Light-Dependent Reactions
• Light-Dependent Reactions use sunlight energy to form ATP (cellular energy).
______________________________________________Light-Independent Reactions
• Light-Independent Reactions or Calvin Cycle, uses ATP and electrons captured from the sun to form sugar compounds.
• Glucose C6H12O6
The calvin cycle was named after Melvin Calvin who traced the chemical path that carbon follows to form glucose.
______________________________________________Photosynthesis: Big Picture
Photosynthetic Sea Slug
The green sea slug is the first animal shown to make chlorophyll like a plant.