Cellular Respiration
All Organisms
CH2O + O2  CO2 + H2O + Energy
Oxidizable Organic Molecule
Cellular Respiration
All Organisms
CH2O + O2  CO2 + H2O + Energy
Oxidizable Organic Molecule
Aerobic & Anaerobic
Cellular Respiration
All Organisms
CH2O + O2  CO2 + H2O + Energy
Oxidizable Organic Molecule Used
Aerobic & Anaerobic
Energy Currency:
Cellular Respiration
All Organisms
CH2O + O2  CO2 + H2O + Energy
Oxidizable Organic Molecule
Aerobic & Anaerobic
Energy Currency: ATP
Photosynthesis
Green Plant Cells
Photosynthesis
Photoautotrophs
C02 + H20  CH2O + O2 + H2O
Oxidizable Organic Molecule Made
Oxygen Produced
Light Dependent
CO2 split?
Photosynthesis
Photoautotrophs
C02 + H20  CH2O + O2 + H2O
Purple Sulfur Bacteria:
CO2 + H2S  CH2O + S
Photosynthesis
Photoautotrophs
C02 + H20  CH2O + O2 + H2O
Purple Sulfur Bacteria:
CO2 + H2S  CH2O + S
Radioactive Isotopes (Plants):
CO2 + H2O  CH2O + O2
CO2 + H2O  CH2O + O2
Photosynthesis
Photoautotrophs
C02 + H20  CH2O + O2 + H2O
Photosynthesis
Photoautotrophs
C02 + H20  CH2O + O2 + H2O
Chloroplast
Chloroplast Structure
Chloroplast
Development of Chloroplasts
(circular DNA)

Protoplastid

Etioplast

Prolamellar body
(chromoplasts or
leucoplasts)

Chloroplast


Photosynthesis
Photoautotrophs
C02 + H20  CH2O + O2 + H2O
Light needed to split water
Pigment Molecules
large complex molecules that can trap
light energy
Photosyntheically Active
Radiation (PAR)
Photosynthesis
Photoautotrophs
C02 + H20  CH2O + O2 + H2O
Light needed to split water
Pigment Molecules
PGAL C3 – 1st Food -> Glucose
Starch
Lipids
Proteins
recycled – CO2 acceptor
RuBP C5
Photosynthesis
Photoautotrophs
C02 + H20  CH2O + O2 + H2O
Pigment Molecules
Chlorophyll a C55H72O5N4Mg
Blue-green
4 tetrapyrole rings
Chlorophyll a
Other Chlorophylls
Chl b – Yell/Green
Chl c
Chl d
Absorption Spectrum of Chlorophylls a and b
Action Spectrum of Photosynthesis
Absorption Spectra
(various photosynthetic pigments)
Carotenoids
(lipids)
Xanthophyll – yellow
(has oxygen)
Carotene – orange/yellow
Alpha & Beta
(lacks oxygen)
Absorption Spectrum of A & B Carotene
Phycobilins
(straight-chain tetrapyrole group attached to a protein)
Phycocyanin (bluish)
Phycoerythrin (reddish)
Phytochromes
Phycocyanin & Phycoerythrin
Absorption Spectra
Absorption Spectrum of the Phytochromes
Accessory Pigments
other chlorophylls, xanthophylls, carotenes ……..


1. Absorb light and pass it on to
chlorophyll a.
2. Prevents photooxidation of
chlorophyll a.
Flavinoids
(water soluble – all absorb UV light)
Anthocyanins
red-purple
(indicator)
Flavones
UV light (bee guides)
Aurones
yellows
Betacyanins
(water soluble – absorb some UV light)
-Contains
Nitrogen
-Found
in plant groups that do not
produce anthocyanins: Chenopodiales –
goosefoots, cactuses, portulacas.
- Red/Yellow (indicator)
Chloroplast
(Within the thylacoid the pigment molecules are
precisely arranged and tightly packed.)
Chlorophyll a
electron transfer
Reaction Center
(1 in 300 molecules)
Antenna Molecules
Accessory Molecules-Photosynthetic Unit
Chloroplast
(Within the thylacoid the pigment molecules are
precisely arranged and tightly packed.)
Part of a Photosynthetic Unit
Accessory pigments feed Reaction
Center
Two types of PUs or Photosystems,
Structured into the Thylacoid Membrane

Photosystem II



more chl b
Photosystem I

680 nm
700 nm
more chl a and carotenoids
Need both red wavelengths for enhanced
photosynthesis

R. Emerson, 1950’s
(Each system carries out certain reactions.
Link by electron acceptors in Light Phase
of Photosynthesis.)
Light Phase
(If components arranged according to energy levels:
Z-Pathway
Light Phase
Photosystem II
Non-cyclic Photophosphorylation
Photosystem I
Non-cyclic Photophosphorylation
Light Phase

Products:

1. NADPH2

2. ATP

(OXIDIZABLE ORGANIC MOLECULES
made in the Dark Phase of
Photosynthesis.)
Light Phase
Light Phase
Triazine Herbicide
Cyclic Photphosphorylation
Cyclic Photophosphorylation
Non-cyclic Photophosphorylation
PCR, Calvin-Benson Cycle
Photosynthetic Carbon Reduction Cycle (PCR)
(Ribulose 1, 5 –Bisphosphate Carboxylase – Rubisco –
CO2 Trapping enzyme)
Oxidative Pentose Phosphate Cycle
(Source of NADPH2 for lipid synthesis: RuMP (C5) for Nucleic
Acid Production)
Enzymes of the Photosynthetic Carbon Reduction Cycle (PCR)
only function with light.
Electron Flow in the Chloroplast
Some Pathways
Warburg Effect
1920’s
RuBp Oxygenase Reaction
(Rubisco)
Favored in High Temp or Low CO2, High O2
“Photorespiration”
RuBp Oxygenase Reaction
(Rubisco)
C4 Plants
In Mesophyll Cells
CO2 + PEP  Oxylate (C4)
 Asparatate & Malate (C4)
 translocates
C4 Plants
Bundle Sheath Cells
C4 Acids  Pyruvate (C3) + CO2 
CO2 + RuBP (C5)  PCR Cycle
The C4 Syndrome
Another Way of Assimilating CO2
Krans Leaf Anatomy
C- 4 Plants
Krans Leaf Anatomy
Mesophyll Chloroplasts
- have grana
Bundle Sheath Chloroplasts
- no grana
- much starch storage
Advantages of C4 Photosynthesis
Advantages of C4 Photosynthesis
1.
Steeper CO2 Utilization Gradient
2.
Decreased Photorespiration
3.
Arrangement of Mesophyll/Bundle
Sheath Cells favorable to Transport
Disadvantages of C4 Photosynthesis
Disadvantages of C4 Photosynthesis
1.
Extra Biochemical Steps (energy
expense)
CAM Plants
- CAM Plants do not have Krans Leaf Anatomy.
- CAM Plants use PEP as a CO2 Trap – as in C4
plants
- CO2 Trapping and PCR cycle separated in
time.
CAM Plants
C4 vs CAM Plants
Ambient Factors Affecting Photosynthesis

Oxygen O2
Ambient Factors Affecting Photosynthesis

Oxygen O2

Light
Effects of Light
(Differences Between C3 and C4 Plants)
Effects of Light

Light-Saturated Photosynthesis



1/3 full sunlight for most plants
(mostly limited by PCR Cycle Reactions)
Light-Limited Photosynthesis


Only at very low light intensities
(Light Compensation point 

Below CO2 accumulation)
Blackman’s Principle of limiting Factors
Shade Plants




Thinner Leaves
More Chlorophylls; Less Carotenoids
(Chl a less protected from
photooxidation)
PSUII:PSUI = 3:1
Lower light compensation point
Sun Plants




Thicker Leaves
Less Chlorophylls; More Carotenoids
(Chl a more protected from
photooxidation)
PSUII:PSUI = 2:1
Higher light compensation point
Ambient Factors Affecting Photosynthesis

Oxygen O2

Light

Temperature
Effect of Temperature
Effect of Temperature
Ambient Factors Affecting Photosynthesis

Oxygen O2

Light

Temperature

CO2 and H2O

Stomatal Action “trade off”