CHAPTER 4
AUTOTROPHY
P.102-122
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
 6CO2 + 6H2O  C6H12O6 +
6O2
 (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.106-110
 TAKES PLACE
IN THE
THYLAKOID
MEMBRANE
(ROUND DISCS
IN THE
CHLOROPLASTS)
 STACKS OF
THYLAKOIDS
ARE CALLED
GRANA
STEPS IN THE PROCESS
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. O2
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.111-112
 USES THE PRODUCTS OF THE
LIGHT REACTIONS (ATP AND
NADPH) ALONG WITH CO2 TO
PRODUCE ORGANIC
COMPOUNDS
 DOES NOT OCCUR IN THE
DARK (NEED LIGHT REACTION
PRODUCTS, SOME ENZYMES
ARE INACTIVE, STOMATES
CLOSE THUS NO CO2)
 OCCURS IN THE STROMA OF
THE CHLOROPLAST AT THE
SAME TIME AS THE LIGHT
REACTIONS
STEPS IN THE PROCESS
1. CO2 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.113-120
 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 CO2 IS
AVAILABLE, RuBP UNITES WITH OXYGEN INSTEAD OF
CO2 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 C3)
 BOTH ARE ADAPTED
TO REDUCE
PHOTORESPIRATION
AND SURVIVE IN
HOT, DRY
ENVIRONMENTS
C4 Plants
 Ex: SUGARCANE, CRABGRASS, CORN
 CO2 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)