Cellular Respiration All Organisms CH 2 O + O 2  CO 2 + H 2 O + Energy Oxidizable Organic Molecule

Cellular Respiration All Organisms CH 2 O + O 2  CO 2 + H 2 O + Energy Oxidizable Organic Molecule Aerobic & Anaerobic

Cellular Respiration All Organisms CH 2 O + O 2  CO 2 + H 2 O + Energy Oxidizable Organic Molecule Used Aerobic & Anaerobic Energy Currency:

Cellular Respiration All Organisms CH 2 O + O 2  CO 2 + H 2 O + Energy Oxidizable Organic Molecule Aerobic & Anaerobic Energy Currency: ATP

Photosynthesis Green Plant Cells

Photosynthesis Photoautotrophs C0 2 + H 2 0  CH 2 O + O 2 + H 2 O Oxidizable Organic Molecule Made Oxygen Produced Light Dependent CO2 split?

Photosynthesis Photoautotrophs C0 2 + H 2 0  CH 2 O + O 2 + H 2 O Purple Sulfur Bacteria: CO 2 + H 2 S  CH 2 O + S

Photosynthesis Photoautotrophs C0 2 + H 2 0  CH 2 O + O 2 + H 2 O Purple Sulfur Bacteria: CO 2 + H 2 S  CH 2 O + S Radioactive Isotopes (Plants): CO 2 + H 2 O  CH 2 O + O 2

Photosynthesis Photoautotrophs C0 2 + H 2 0  CH 2 O + O 2 + H 2 O

Chloroplast

Chloroplast Structure

Chloroplast

Development of Chloroplasts (circular DNA)  Protoplastid  Etioplast  Prolamellar body  (chromoplasts or  leucoplasts)  Chloroplast

Photosynthesis Photoautotrophs C0 2 + H 2 0  CH 2 O + O 2 + H 2 O Light needed to split water Pigment Molecules large complex molecules that can trap light energy

Photosyntheically Active Radiation (PAR)

Photosynthesis Photoautotrophs C0 2 + H 2 0  CH 2 O + O 2 + H 2 O Light needed to split water Pigment Molecules PGAL C 3 – 1 st Food -> Glucose Starch Lipids Proteins recycled – CO 2 acceptor RuBP C 5

Photosynthesis Photoautotrophs C0 2 + H 2 0  CH 2 O + O 2 + H 2 O Pigment Molecules Chlorophyll a C 55 H 72 O 5 N 4 Mg 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 (lacks oxygen) Alpha & Beta

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 680 nm more chl b  Photosystem I 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. NADPH 2  2. ATP  (OXIDIZABLE ORGANIC MOLECULES made in the Dark Phase of Photosynthesis.)

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 CO 2, High O 2 “Photorespiration”

RuBp Oxygenase Reaction (Rubisco)

C 4 Plants In Mesophyll Cells CO 2 + PEP  Oxylate (C 4 )  Asparatate & Malate (C 4 )  translocates

C 4 Plants Bundle Sheath Cells C 4 Acids  Pyruvate (C 3 ) + CO 2  CO 2 + RuBP (C 5 )  PCR Cycle

The C 4 Syndrome Another Way of Assimilating CO 2

Krans Leaf Anatomy

C- 4 Plants Krans Leaf Anatomy Mesophyll Chloroplasts - have grana Bundle Sheath Chloroplasts - no grana - much starch storage

Advantages of C 4 Photosynthesis

1. Steeper CO 2 Utilization Gradient 2. Decreased Photorespiration 3. Arrangement of Mesophyll/Bundle Sheath Cells favorable to Transport

Disadvantages of C 4 Photosynthesis

1. Extra Biochemical Steps (energy expense)

CAM Plants - CAM Plants do not have Krans Leaf Anatomy. - CAM Plants use PEP as a CO 2 Trap – as in C 4 plants - CO2 Trapping and PCR cycle separated in time.

CAM Plants

C 4 vs CAM Plants

Ambient Factors Affecting Photosynthesis  Oxygen O 2

Ambient Factors Affecting Photosynthesis  Oxygen O 2  Light

Effects of Light (Differences Between C 3 and C 4 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 CO 2 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 O 2  Light  Temperature

Effect of Temperature

Ambient Factors Affecting Photosynthesis  Oxygen O 2  Light  Temperature  CO 2 and H 2 O Stomatal Action “trade off”