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TRANSCRIPT
Autotrophs
Plants, algae, and cyanobacteria contain chlorophyll. This pigment trapslight energy from the sun to produce food.
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Autotrophs
• Autotrophs include organisms that make their own food
• Autotrophs can use the sun’s energy directly Euglena
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Heterotrophs
• Heterotrophs are organisms that can NOT make their own food
• Heterotrophs can NOT directly use the sun’s energy
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Energy
• Energy Takes Many Forms such as light, heat, electrical, chemical, mechanical
• Energy can be changed from one form to another
• Energy can be stored in chemical bonds & then released later
Candles release energy as HEAT & LIGHT 5
ATP – Cellular Energy
• Adenosine Triphosphate• The energy is stored in the two, high-
energy phosphate bonds• Also contains the nitrogen base adenine
& a ribose sugar
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ADP• Adenosine Diphosphate• ATP releases energy, a free phosphate, & ADP when cells take energy from ATP
One phosphate bond has been removed 7
Releasing Energy From ATP
• ATP is constantly being used and remade by cells
• ATP provides all of the energy for cell activities
• The high energy phosphate bonds can be BROKEN to release energy
• The process of releasing ATP’s energy & reforming the molecule is called phosphorylation
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Releasing Energy From ATP
• Adding A Phosphate Group To ADP stores Energy in ATP
• Removing A Phosphate Group From ATP Releases Energy & forms ADP
Loose
Gain
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Cells Using Biochemical Energy
Cells Use ATP For:• Active transport• Movement• Photosynthesis• Protein Synthesis• Cellular respiration• All other cellular reactions
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More on ATP
• Cells Have Enough ATP To Last For A Few Seconds
• ATP must constantly be made
• ATP Transfers Energy Very Well
• ATP Is NOT Good At Energy Storage
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Glucose
• Glucose is a monosaccharide
• C6H12O6
• One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP
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Photosynthesis
• Involves the Use Of light Energy to convert Water (H20)and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches
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Pigments
• In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments
• Chlorophyll is the primary light-absorbing pigment in autotrophs
• Chlorophyll is found inside chloroplasts
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Light and Pigments
• Energy From The Sun Enters Earth’s Biosphere As Photons
• Photon = Light Energy Unit
• Light Contains A Mixture Of Wavelengths
• Different Wavelengths Have Different Colors
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Light & Pigments
• Different pigments absorb different wavelengths of light
• Photons of light “excite” electrons in the plant’s pigments
• Excited electrons carry the absorbed energy
• Excited electrons move to HIGHER energy levels
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Chlorophyll
There are 2 main types of chlorophyll molecules:
Chlorophyll aChlorophyll b
A third type, chlorophyll c, is found in dinoflagellates
Magnesium atom at the center of chlorophyll19
Chlorophyll a
•Found in all plants, algae, & cyanobacteria•Makes photosynthesis possible•Participates directly in the Light Reactions•Can accept energy from chlorophyll b
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Chlorophyll b
• Chlorophyll b is an accessory pigment
• Chlorophyll b acts indirectlyin photosynthesis by transferring the light it absorbs to chlorophyll a
• Like chlorophyll a, it absorbs red & blue light and REFLECTS GREEN
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Structure of the Chloroplast
• Inner membraneforms stacks of connected sacs called thylakoids
• Thylakoid stack is called the granum(grana-plural)
Function of the Stroma
• Light Independentreactions occur here
• ATP used to make carbohydrates like glucose
• Location of the Calvin Cycle
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Thylakoid membranes• Light Dependent reactions occur here
• Photosystems are made up of clusters of chlorophyll molecules
• Photosystems are embedded in the thylakoid membranes
• The two photosystems are:Photosystem IPhotosystem II 29
• Occurs across the thylakoid membranes
• Uses light energy• Produce Oxygen from water• Convert ADP to ATP• Also convert NADP+ into the energy carrier NADPH
Light Dependent Reactions
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Photosystem I and II
Photosystem IMade of 300 molecules of Chlorophyll…mostly chlorophyll a
Photosystem IIContains about equal amounts of chlorophyll a and chlorophyll b 34
Photosystem IHigh-energy electrons are moved to Photosystem I through the Electron Transport Chain
Energy is used to transport H+ from stroma to inner thylakoid membrane
NADP+ converted to NADPH when it picks up 2 electrons & H+
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Light Independent Reaction
• ATP & NADPH from light reactions used as energy
• Atmospheric C02 is used to make sugars like glucose and fructose
• Six-carbon Sugars made during the Calvin Cycle
• Occurs in the stroma38
The Calvin Cycle• Two turns of the Calvin Cycle are required to make one molecule of glucose
• 3-CO2 molecules enter the cycle to form several intermediate compounds (PGA)
• A 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycle
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