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PHOTOSYNTHESIS: Energy within light is captured and used to synthesize…
PHOTOSYNTHESIS: Energy within light is captured and used to
synthesize carbohydrates
TROPHIC LEVELS
autotroph
makes organic molecules from inorganic, e.g: CO2, H2O
photoautotroph
use light as a source of energy, e.g: green plants
heterotroph
must eat food, e.g: bacteria
PHOTOSYNTHETIC PIGMENT
Absorption boosts electrons to higher energy levels = excited electron state then transferred or captured to another molecules
release energy as: heat or light
CHLOROPLAST
chlorophyll
Green pigment
photosynthesis occurs in the mesophyll
CO2, O2 exits leaf through stomata
granum
stack of thylakoids
stroma
Fluid filled region between thylakoid
membrane and inner membrane
cells use organic molecules for energy and plants replenish those molecules using photosynthesis
TWO STAGES
light reaction
produce: ATP, NADPH and O2
take place in thylakoid membrane
calvin cycle
occurs in stroma
uses ATP, NADPH and CO2 to make carbohydrates
ABSORPTION VS. ACTION SPECTRUM
absorption
Wavelengths that are absorbed by different pigments
action
Rate of photosynthesis by whole plant at specific wavelengths
PHOTOSYSTEM
Photosystem
Primary role to make NADPH
cyclic electron flow
Photosystem II
Energy used to make H+ electrochemical gradient
Excited electrons travel from PSII to PSI
initial step
linear process- Non cyclic
2 main component
reaction center
P680 → P680*
energy is transferred quickly
Light-harvesting complex
absorbs photons
energy transferred via resonance energy transfer
3 chemical products
oxygen
NADPH
ATP
Synthesizing Carbohydrates
via the Calvin Cycle
Requires massive input of energy
for every 6 CO2 incorporated
12 NADPH
18 ATP
Product is G3P
CO2 incorporated into carbohydrates
3 phases
phase 2: Reduction and carbohydrate production
phase 3: Regeneration of RuBP
phase 1: Carbon fixation
PHOTORESPIRATION
C3 plants
cooler climates, most of plants are C3
CAM plants
separate process
open their stomata at knight
oxaloacetate converted to malate
malate leave central vacuole and broken down into CO2
C4 plants
minimize photorespiration, make oxaloacetate, hatch slack pathways, leaves have 2-cell layer (mesophyll cells - bundle sheet cells)
ENERGY CYCLE
CHAPTER 8
