CHAPTER 4 AUTOTROPHY P

2 TYPES OF AUTOTROPHS ( REVIEW FROM ECOSYSTEMS AND ENERGY CHAPTER ) 1. PHOTOAUTOTROPHS  PLANTS, ALGAE, SOME BACTERIA USE OF SUNLIGHT  PHOTOSYNTHESIS 2. CHEMOAUTOTROPHS  SOME BACTERIA USE OF CHEMICAL REACTIONS (CHEMICALS)  CHEMOSYNTHESIS

THE PROCESS OF PHOTOSYNTHESIS 1. ABSORPTION OF LIGHT ENERGY 2. CONVERSION OF LIGHT ENERGY INTO CHEMICAL ENERGY 3. STORAGE OF CHEMICAL ENERGY (SUGARS AND STARCHES)

LIGHT ENERGY 1. TRAVELS AS WAVES 2. VISIBLE LIGHT IS ABSORBED/REFLECTED IN THE PROCESS OF PHOTOSYNTHESIS BY CHLOROPHYLL A (MAINLY) AND OTHER ACCESSORY PIGMENTS 3. THE SHORTER THE WAVELENGTH,THE MORE ENERGY ( R, O, Y, G, B, I, V ) 4. PLANTS APPEAR GREEN DUE TO CHLOROPHYLL REFLECTING GREEN LIGHT WHILE ABSORBING MAINLY RED AND BLUE

THE EQUATION OF PHOTOSYNTHESIS 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 (IN THE PRESENCE OF LIGHT AND CHLOROPHYLL A ) A 2 PART PROCESS  LIGHT REACTIONS AND LIGHT INDEPENDENT REACTIONS MOST IMPORTANT ASPECT  CONVERT LIGHT ENERGY INTO CHEMICAL ENERGY

THE LIGHT REACTIONS p TAKES PLACE IN THE THYLAKOID MEMBRANE ( ROUND DISCS IN THE CHLOROPLASTS ) STACKS OF THYLAKOIDS ARE CALLED GRANA

STEPS IN THE PROCESS 1. 1.LIGHT IS ABSORBED BY CHLOROPHYL L A IN CLUSTERS OF PIGMENTS CALLED PHOTOSYSTE MS (LABELED PSI AND PSII)

STEPS IN THE PROCESS 2. THIS LIGHT ENERGY IS TRANSFERRED TO A REACTION CENTER ( ONLY CHLOROPHYLL A PARTICIPATES IN ELECTRON FLOW )

STEPS IN THE PROCESS 3. HIGH ENERGY ELECTRONS ARE RELEASED FROM REACTION CENTER MOLECULES ( THESE ELECTRONS ARE PASSED BETWEEN THE 2 PHOTOSYSTEMS )

STEPS IN THE PROCESS 4. AT PSII, THE LIGHT ENERGY SPLITS APART WATER MOLECULES, WITH TWO ELECTRONS (e-), TWO PROTONS (H+), AND AN OXYGEN (O) PRODUCED. O 2 IS RELEASED INTO THE ATMOSPHERE.

STEPS IN THE PROCESS 5. THE ELECTRONS ARE TRANSPORTED DOWN AN ELECTRON TRANSPORT SYSTEM (ETS) (THIS CAUSES THE H+ IONS TO BE PUMPED INTO THE SPACE BETWEEN THE THYLAKOID MEMBRANES)

STEPS IN THE PROCESS 6. H+ IONS THEN DIFFUSE OUT OF THE THYLAKOID SPACE THROUGH THE ENZYME ATP SYNTHASE, WHICH FORMS ATP IN THE STROMA

STEPS IN THE PROCESS 7. THE ELECTRONS AND H+ IONS COMBINE WITH THE CHEMICAL NADP TO PRODUCE NADPH IN THE STROMA. **THE PRODUCTS OF THE LIGHT REACTIONS ATP AND NADPH ARE USED IN THE CALVIN CYCLE**

THE CALVIN CYCLE P USES THE PRODUCTS OF THE LIGHT REACTIONS ( ATP AND NADPH ) ALONG WITH CO 2 TO PRODUCE ORGANIC COMPOUNDS DOES NOT OCCUR IN THE DARK ( NEED LIGHT REACTION PRODUCTS, SOME ENZYMES ARE INACTIVE, STOMATES CLOSE THUS NO CO 2 ) OCCURS IN THE STROMA OF THE CHLOROPLAST AT THE SAME TIME AS THE LIGHT REACTIONS

STEPS IN THE PROCESS 1. CO 2 COMBINES WITH RuBP ( USING THE ENZYME RUBISCO ) TO PRODUCE PGA. THIS IS CALLED CARBON FIXATION

STEPS IN THE PROCESS 2. USING ATP AND NADPH FROM THE LIGHT REACTIONS, PGA IS CONVERTED TO PGAL

STEPS IN THE PROCESS 3. MOST OF THE PGAL IS USED TO MAKE MORE RuBP WHILE SOME IS USED TO MAKE ORGANIC COMPOUNDS SUCH AS GLUCOSE THE PLANT CAN USE ( 6 TURNS OF THE CYCLE EQUALS YEILDS 1 GLUCOSE MOLECULE )

PHOTOSYNTHESIS AND THE ENVIRONMENT P RATES OF PHOTOSYNTHESIS DETERMINED BY LIGHT INTENSITY, CARBON DIOXIDE, TEMPERATURE, OXYGEN AT A CERTAIN POINT, PHOTOSYNTHESIS WILL REACH AN OPTIMUM LEVEL SEE SAMPLE GRAPHS A DECLINE IN PHOTOSYNTHESIS IS KNOWN AS PHOTOINHIBITION

SPECIAL ADAPTATIONS OF PLANTS PHOTORESPIRATION  WHEN NOT ENOUGH CO 2 IS AVAILABLE, RuBP UNITES WITH OXYGEN INSTEAD OF CO 2 TO FORM ONE PGA AND ONE GLYCOLATE (A 2 CARBON ACID) INSTEAD OF 2 PGA IN THE CALVIN CYCLE ONLY WORKS AT HALF THE EFFICIENCY AS PHOTOSYNTHESIS THIS PROCESS IS DUE TO INCREASED OXYGEN IN THE ATMOSPHERE ( ACTUALLY FROM PLANTS THEMSELVES )

2 TYPES OF PLANTS (OTHER THAN C 3 ) BOTH ARE ADAPTE D TO REDUCE PHOTORESPIRATION AND SURVIVE IN HOT, DRY ENVIRONMENTS

C 4 Plants Ex: SUGARCANE, CRABGRASS, CORN CO 2 COMBINES WITH 3 CARBON ACID IN MESOPHYLL CELLS ( CARBON FIXATION ) THE 4 CARBON ACID THAT IS PRODUCED THEN GOES TO THE BUNDLE SHEATH CELLS WHERE THE CALVIN CYCLE FUNCTIONS

CAM Plants DESERT PLANTS SUCH AS CACTUS AND PINEAPPLE STOMATES OPEN AT NIGHT AND CLOSED DURING THE DAY ( WHEN THE CALVIN CYCLE OCCURS ) THIS IS DONE TO CONSERVE WATER

PHOTOSYNTHESIS QUIZ FORMAT 35 TOTAL POINTS 29 MULTIPLE CHOICE 3 SHORT ANSWER ( 2 PTS. EACH ) 2 BONUS SHORT ANSWER ( ALL 5 ARE FROM THE HW ANSWERS )