photosynthesis: using light to make food. photosynthesis: using light energy to make food...
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PHOTOSYNTHESIS: USING LIGHT TO MAKE FOOD
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• HETEROTROPHS VS AUTOTROPHS?• AUTOTROPHS (A.K.A ?)– DEFINITION?
• TWO TYPES– PHOTOSYNTHETIC VS CHEMOSYNTHETIC
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• PHOTOSYNTHESIS OCCURS IN ??
• ALL GREEN PARTS OF THEPLANT CONTAIN THEM
• WHY IS IT ALL THE PARTSARE GREEN?
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• CHLOROPHYLL ABSORBS ABSORBS LIGHT ENERGY FOR PHOTOSYNTHESIS
• CHLOROPLASTS ARE CONCENTRATED IN THE MESOPHYLL– MESOPHYLL?
• HOW DOES CARBON DIOXIDE GET IN?
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• CHLOROPLAST STRUCTURE
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• QUICK REVIEW QUESTION…WHERE DOES THE CARBON DIOXIDE WE BREATH OUT COME FROM? WHERE DOES THE WATER WE BREATH OUT COME FROM?
• WHERE DOES THE OXYGEN PLANTS GIVE OFF COME FROM?
• USING RADIOACTIVE ELEMENTS WE HAVE BEEN ABLE TO FIGURE OUT WHAT THE ELEMENTS INVOLVED IN PHOTOSYNTHESIS DO
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• PHOTOSYNTHESIS IS A REDOX RXN!!
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• PHOTOSYNTHESIS: AN OVERVIEW
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• PHOTOSYNTHESIS OCCURS IN TWO MAIN STAGES– THE LIGHT REACTION (LIGHT-DEPENDENT RXN)• DEFINITION
– THE DARK REACTION (LIGHT-INDEPENDENT RXN)• DEFINITION
– CARBON FIXATION
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• VISIBLE LIGHT DRIVES THE LIGHT REACTION– ELECTROMAGNETIC SPECTRUM• WAVELENGTHS DETERMINE PROPERTIES
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• LIGHT ABSORBING PIGMENTS ABSORB LIGHT ENERGY FROM THE VISIBLE SPECTRUM
• CHLOROPHYLL A• CHLOROPHYLL B• CAROTENOIDS
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• PHOTOSYNTHESIS CAPTURES SOLAR ENERGY• PHOTONS– DEFINTION?
• PHOTOSYSTEMS– DEFINITION?
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• TWO TYPES OF PHOTOSYSTEMS PHOTOSYSTEM I
(P 700)PHOTOSYSTEM II
(P 680)
NAMED IN
ORDER OF
DISCOVERY,
NOT ORDER
THEY
OCCUR
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• THE LIGHT REACTION– GENERATES ATP,
NADPH, AND OXYGEN– OCCURS IN THE
THYLAKOIDS
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• THE LIGHT REACTION
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• THE LIGHT REACTION (IN WORDS)– LIGHT ENERGY FROM THE SUN IS ABSORBED BY ELECTRONS OF
CHLOROPHYLL IN THE PHOTOSYSTEMS– THOSE ELECTRONS ARE REPLACED WHEN WATER IS SPLIT BY
PHOTOLYSIS– THE HIGH ENERGY ELECTRONS FROM THE PHOTOSYSTEMS ARE
PASSED THROUGH ELECTRON TRANSPORT CHAINS IN THE THYLAKOID MEMBRANES
– THE ELECTRON TRANSPORT CHAINS CREATE A PROTON GRADIENT ACROSS THE THYLAKOID MEMBRANE
– CHEMIOSMOSIS POWERS ATP PRODUCTION (PHOTOPHOSPHORYLATION)
– THE FINAL PRODUCTS ARE ATP, NADPH, AND OXYGEN!!!
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• THE DARK REACTION (A.K.A. CALVIN CYCLE)
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• THE DARK REACTION– AT THIS POINT, LIGHT ENERGY HAS BEEN
CONVERTED INTO ATP AND NADPH– THE DARK REACTION (LIGHT-INDEPENDENT
REACTION) CONVERTS THAT ENERGY INTO THE CHEMICAL ENERGY OF AN ORGANIC COMPOUND
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• CALVIN CYCLE (STEPS)– 3 CO2 ENTER THE STROMA, AND WITH THE HELP OF THE
ENZYME RUBISCO COMBINES WITH 3 MOLECULES OF THE 5-CARBON COMPOUND RIBULOSE BIPHOSPHATE (RUBP)
– THIS RESULTS IN 6 MOLECULES OF THE 3-CARBON COMPOUND PGA (PHOSPHOGLYCERATE)
– THE ENERGY FROM ATP AND NADPH IS USED TO CONVERT THE 6 PGA’S INTO 6 G3P MOLECULES (GLYCERALDEHYDE-PHOSPHATE)
– 1 3-CARBON G3P MOLECULE IS GIVEN OFF, THE OTHER FIVE ARE USED TO REGENERATE THE ORIGINAL 5-CARBON RUBP
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• WE REFER TO MOST PLANTS AS C-3 PLANTS, BECAUSE THEIR PHOTOSYNTHETIC PATHWAY CREATES A 3-CARBON COMPOUND INITIALLY IN THE CALVIN CYCLE
• HOWEVER, WHAT HAPPENS IF THE STOMATES ARE OPEN TOO LONG? WHAT HAPPENS IF THE CLIMATE IS TOO HOT?
• PHOTORESPIRATION RESULTS WHEN STOMATES ARE CLOSED FOR EXTENDED PERIODS– PHOTORESPIRATION DEF??
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• C4 AND CAM PLANTS HAVE ADAPTATIONS TO SAVE WATER– HAVE EXTRA
STEPS INVOLVED INPHOTOSYNTHESISTO CONSERVEWATER
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• C4 PLANTS HAVE AN ENZYME THAT CREATE A 4 CARBON COMPOUND FROM CO2
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• WHAT ADVANTAGE IS THEIR FOR A C4 PLANT? WHY BOTHER CONVERTING THE CO2?
• WHAT ABOUT CAM PLANTS?– CAM = CRASSULACEAN ACID METABOLISM– CO2 IS CONVERTED TO CRASSULACEAN ACID FIRST– TYPICALLY ONLY OCCURS IN DESERT PLANTS;
STOMATES ONLY OPEN AT NIGHT– IF THEY ARE ONLY OPEN AT NIGHT, WHY IS THIS
PROCESS SO IMPORTANT?
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• HOW DOES PHOTOSYNTHESIS HELP TO COUNTERACT GLOBAL WARMING??
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
• WHEN WE DREW THE CROSS SECTION OF A LEAF, WE SAW IT WAS MADE UP OF MANY CELLS…BUT HOW DO WE GO FROM SINGLECELLED ORGANISMS,TO MULTICELLULARORGANISMS??
• YOU’LL JUST HAVE TO COME BACK TO FINDOUT!!!!!
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD
PHOTOSYNTHESIS: USING LIGHT ENERGY TO MAKE FOOD