PHOTOSYNTHESIS

Views:
 
Category: Education
     
 

Presentation Description

Plant Photosynthesis

Comments

Presentation Transcript

PowerPoint Presentation:

PHOTOSYNTHESIS Photosynthesis, importance of photosynthesis, structure and function of chloroplast, dark and light reaction, CO 2 fixation, C3,C4 and CAM, advantages of C4 pathway, photorespiration and its implications, Factors affecting photosynthesis.

PowerPoint Presentation:

Energy can not be produce or destroyed , it can only transformed from one form to another The sun: main source of energy for life on earth

PowerPoint Presentation:

Light Energy Harvested by Plants & Other Photosynthetic Autotrophs

PowerPoint Presentation:

Photosynthesis and energy Photosynthesis and food. Photosynthesis, fiber, and materials Photosynthesis and the environment Photosynthesis and agriculture Photosynthesis and energy production Photosynthesis and electronics Photosynthesis and medicine Why study photosynthesis ?

PowerPoint Presentation:

Evolution of Photosynthesis

PowerPoint Presentation:

Why are plants green? Reflected light Transmitted light

Structure of Leaf:

Structure of Leaf upper epidermis protect internal tissues from mechanical damage and bacterial and fungal invasion

Structure of Leaf:

Cuticle a waxy layer prevent water loss from the leaf surface Structure of Leaf

Structure of Leaf:

mesophyll Structure of Leaf

Structure of Leaf:

palisade mesophyll columnar cells closely packed together absorb light more efficiently contains many chloroplasts Structure of Leaf

Structure of Leaf:

spongy mesophyll irregular cells loosely packed together to leave numerous large air spaces allow rapid diffusion of gases throughout the leaf less chloroplasts for photosynthesis Structure of Leaf

Structure of Leaf:

lower epidermis same as upper epidermis except the cuticle is thinner Structure of Leaf

Structure of Leaf:

stoma opening which allows gases to pass through it to go into or out of the leaf Structure of Leaf

Structure of Leaf:

guard cells control the size of stoma Structure of Leaf

Structure of Leaf:

vascular bundle (vein) Structure of Leaf

Structure of Leaf:

xylem to transport water and mineral salts towards the leaf Structure of Leaf

Structure of Leaf:

phloem to transport organic substances away from the leaf Structure of Leaf

Adaptation of leaf to photosynthesis:

Adaptation of leaf to photosynthesis Upper epidermis and cuticle is transparent Allows most light to pass to photosynthetic mesophyll tissues

Adaptation of leaf to photosynthesis:

Palisade mesophyll cells are closely packed and contain many chloroplasts To carry out photosynthesis more efficiently Adaptation of leaf to photosynthesis

Adaptation of leaf to photosynthesis:

Spongy mesophyll cells are loosely packed with numerous large air spaces To allow rapid diffusion of gases throughout the leaf Adaptation of leaf to photosynthesis

Adaptation of leaf to photosynthesis:

Numerous stomata on lower epidermis To allow rapid gaseous exchange with the atmosphere Adaptation of leaf to photosynthesis

Adaptation of leaf to photosynthesis:

Extensive vein system Allow sufficient water to reach the cells in the leaf To carry food away from them to other parts of the plant Adaptation of leaf to photosynthesis

PowerPoint Presentation:

Photosynthesis The chlorophyll molecules in the chloroplasts are essential in the process of photosynthesis . Protein Synthesis Chloroplasts are capable of doing Protein Synthesis. Carriers of Heredity Characters Chloroplasts have a limited role in cytoplasmic inheritance since these contain traces of DNA. Function of chloroplast:

PowerPoint Presentation:

Chlorophyll is the molecule that traps this 'most elusive of all powers' - photoreceptor. It is found in the chloroplasts of green plants, The basic structure of a chlorophyll molecule is a porphyrin ring , co- ordinated to a central atom. This is very similar in structure to the heme group found in hemoglobin, except that in heme the central atom is iron, whereas in chlorophyll it is magnesium. Chlorophyll

PowerPoint Presentation:

Photosynthesis Mechanism:

PowerPoint Presentation:

PHOTOSYNTHESIS Solar energy to Chemical energy Oxidation – Reduction process Light Water Protons + Electrons Pigments Assimilatory Powers CO 2 Carbohydrate Oxidation Reduction

PowerPoint Presentation:

Temperature coefficient Intermittent light Tracer technique Evidence of Light and Dark reaction:

PowerPoint Presentation:

Red drop sharp decrease in quantum yield at wavelength greater than 680 nm, in the red part of the spectrum, the phenomenon was called as red drop Emerson enhancement effect inefficient far-red light beyond 680 nm could be made fully efficient if supplemented with RED light

PowerPoint Presentation:

LIGHT REACTION Production of Assimilatory Powers (ATP and NADPH) by light, water and pigments Absorption of light energy by the pigments 2. Activation of Chlorophyll molecule 3. Photolysis of water 4. Electron Transport Chain 5. Synthesis of Assimilatory Powers

PowerPoint Presentation:

Absorption of Light Energy All pigments – Absorb – Light Energy – Transfer to – Chlorophyll a Chlorophyll a – Absorb and Conversion – To Chemical Energy PHOTOSYSTEM Group of Pigments PS І (P 700) More Chlorophyll Less Accessory Pigments PS І (P 700) Less Chlorophyll More Accessory Pigments PS ІІ (P 680)

PowerPoint Presentation:

Different chloroplast pigments absorb light in different regions of the visible part of the spectrum Absorption of light energy by chloroplast pigments

PowerPoint Presentation:

Transfer of light energy from accessory pigments to chlorophyll a

PowerPoint Presentation:

Prepared By: KIRTI BARDHAN     The chlorophyll molecule becomes excited (this takes only 10 -15 sec = fempto sec ) and an electron moves to an outer energy level. CHL (ground state) → CHL* (excited state)     Electrons don’t stay excited long (10 -9 sec), because they either: return to the ground state and release their absorbed energy as heat ( thermal deactivation ); return to ground state and release their extra energy as light ( fluorescence ); transfer their energy to another molecule; kind of like hitting pool balls ( resonance transfer ); or be used in a photochemical reaction ( photochemistry ). What happens when chlorophyll absorbs light?

PowerPoint Presentation:

Ground state Excited second singlet state Excited second singlet state Heat loss Chl a Chl a Activation of chlorophyll molecule by photon of light fluorescence Light Meta stable Triplet state phosphorescence

PowerPoint Presentation:

Photosystem : Two physically and chemically distinct photosystems (I and II), each with its own antenna pigments and photochemical reaction center.The two photosystems are linked by an electron transport chain

PowerPoint Presentation:

 PSI  PSII  Is located on the outer surface of non appressed parts of grana thylakoids.  Is located on the inner surface of appressed parts of grana thylakoids.  Comprises of about 200 - 400 chlorophylls, 50 carotenoids , one molecules of P 700  Comprises of about 200 chlorophylls, 50 carotenoids, one molecules of P 680  Is light green in colour  Is dark green in colour  Is not directly involved with photooxidation of H 2 O and evolution of molecules of O 2  Is directly involved with photooxidation of H 2 O and evolution of molecules of O 2

How the Light Reactions Generate ATP and NADPH:

2 H  + 1 / 2 Water-splitting photosystem Reaction- center chlorophyll Light Primary electron acceptor Energy to make Electron transport chain Primary electron acceptor Primary electron acceptor NADPH-producing photosystem Light NADP  1 2 3 How the Light Reactions Generate ATP and NADPH

PowerPoint Presentation:

Prepared By: KIRTI BARDHAN Cyclic Photophosphorylation Process for ATP generation associated with some Photosynthetic Bacteria Reaction Center => 700 nm

PowerPoint Presentation:

Prepared By: KIRTI BARDHAN Cyclic photophosphorylation

PowerPoint Presentation:

Prepared By: KIRTI BARDHAN

PowerPoint Presentation:

Primary electron acceptor Primary electron acceptor Electron transport chain Electron transport Photons PHOTOSYSTEM I PHOTOSYSTEM II Energy for synthesis of by chemiosmosis Noncyclic Photophosphorylation Photosystem II regains electrons by splitting water, leaving O 2 gas as a by-product

PowerPoint Presentation:

Prepared By: KIRTI BARDHAN Noncyclic Photophosphorylation

PowerPoint Presentation:

Photon Photon Water-splitting photosystem NADPH-producing photosystem ATP mill Two types of photosystems cooperate in the light reactions

In the light reactions, electron transport chains generate ATP, NADPH, & O2:

Two connected photosystems collect photons of light and transfer the energy to chlorophyll electrons The excited electrons are passed from the primary electron acceptor to electron transport chains Their energy ends up in ATP and NADPH In the light reactions, electron transport chains generate ATP, NADPH, & O 2

Chemiosmosis powers ATP synthesis in the light reactions:

The electron transport chains are arranged with the photosystems in the thylakoid membranes and pump H + through that membrane The flow of H + back through the membrane is harnessed by ATP synthase to make ATP In the stroma, the H + ions combine with NADP + to form NADPH Chemiosmosis powers ATP synthesis in the light reactions

PowerPoint Presentation:

The Light Reaction

PowerPoint Presentation:

PHOTOSYNTHESIS LIGHT REACTION DARK REACTION PRIMARY PHOTOCHEMICAL REACTION PATH OF CARBON IN PS HILL’S REACTION BLACK MAN’S REACTION OR OR OR OR

PowerPoint Presentation:

DARK REACTION Reduction of CO 2 to Carbohydrate by utilizing Assimilatory Powers (ATP and NADPH 2 ) Produced by Light Reaction DARK REACTION C 3 PATHWAY CALVIN CYCLE REDUCTIVE PENTOSE PHOSPHATE [ RPP ] CYCLE C 4 Pathway Hatch and Slack Cycle CAM Pathway

PowerPoint Presentation:

Calvin cycle or C3 cycle Calvin cycle was first observed by Melvin Calvin in chlorella Calvin was awarded Nobel Prize for this work in 1961 It is a cyclic reaction occurring in the dark phase of photosynthesis CO 2 is converted into sugars and it is a process of carbon fixation First stable compound in Calvin cycle is a 3 carbon compound (3 phosphoglyceric acid) cycle is also called as C3 cycle

PowerPoint Presentation:

Synthesis of carbohydrate Ribulose 1,5 diphosphate + CO2+H2O  3 Phosphoglyceric acid (2 molecule) Rubisco 3 PGA + NADPH + H  3 Phosphoglyceral aldehyde ATP + Triose phosphate dehydrogenase 3 Phosphoglyceral aldehyde  Dihydroxy acetone phosphate Triose phosphate isomerase 3 Phosphoglyceral aldehyde  Fructose 1,6 diphosphate + Dihydroxy acetone phosphate Aldolase

PowerPoint Presentation:

Regeneration of Ribulose diphosphate Fructose 6 phosphate + 3 Phosphoglyceraldehyde  Erythrose 4 phosphate + Xylose-5- phosphate Transketolasec Erythrose 4 phosphate + Dihydroxy acetone phosphate Sedoheptulose 1, 7 diphosphate Sedoheptulose 7 diphosphate Aldolase Phosphatase

PowerPoint Presentation:

Sedoheptulose- 7- phosphate 3 Phosphoglyceraldehyde Xylose 5 phosphate + Ribose 5 Phosphate Transketolase Phosphopentose isomerase Ribulose 5 phosphate + ATP Ribulose, 1, 5 diphosphate Phosphopentokinase

PowerPoint Presentation:

Prepared By: KIRTI BARDHAN High light intensity Low CO2, High O2 Photorespiration

PowerPoint Presentation:

Prepared By: KIRTI BARDHAN

PowerPoint Presentation:

C4 cycle / Hatch and Slack / C4 dicarboxylic acid pathway It is the alternate pathway of C3 cycle to fix CO2 first formed stable compound 4 carbon oxaloacetic acid Enzyme - PEP corboxylase different type of leaf anatomy- chloroplasts are dimorphic in nature vascular bundles are surrounded by bundle sheath of larger parenchymatous cells have chloroplasts chloroplasts of bundle sheath are larger, lack grana peculiar anatomy of leaves of C4 plants is called Kranz anatomy Eg : sugar cane, maize, sorghum and amaranthus

PowerPoint Presentation:

C 4 cycle consists of four stages 1. Fixation of CO2 by the carboxylation of phosphoenolpyruvate in the mesophyll cells to form a C4 acid ( malate and/or aspartate ) 2 . Transportation of the C4 acids to the bundle sheath cells Decarboxylation of the C4 acids within the bundle sheath cells and generation of CO2, which is then reduced to carbohydrate via Calvin cycle 4. Transport of the C3 acid ( pyruvate or alanine ) that is formed by the decarboxylation step back to the mesophyll cell and regeneration of the CO2 acceptor phosphoenolpyruvate

PowerPoint Presentation:

C 3 leaf C 4 leaf

PowerPoint Presentation:

Structural specification of C4 plants: Dimorphism of chloroplast Kranz anatomy Differences b/w C3 and C4 Plants CO2 acceptor and stable product Efficiency of CO2 absorption (CO2 compensation point) Type of chloroplast Calvin cycle enzymes Light saturation point Photorespiration Optimum temp.

PowerPoint Presentation:

Biological Significance of C4 plants Photosynthesis in low CO 2 Xeric condition – partial stomatal closure Absence of photorespiration, higher fixation

PowerPoint Presentation:

CAM( Crassulation acid metabolism) Fixation

PowerPoint Presentation:

Prepared By: KIRTI BARDHAN

PowerPoint Presentation:

CAM Photosynthesis

PowerPoint Presentation:

C3 C4 CAM Leaf anatomy no distinct bundle sheath Kranz anatomy Usually no palisade cells, large vacuoles Initial carboxylating enzyme rubisco PEPcase PEPcase Product of CO 2 fixation PGA (C3) OAA (C4) OAA (C4) Chloroplasts one type dimorphic one type Theoretical energy requirements (CO 2 : ATP: NADPH) 1: 3: 2 1: 5 : 2 1: 6.5: 2 Transpiration ratio (g H 2 O/g dry wt) 450-950 250-350 18-125 Photosynthesis rate (mg CO 2 fixed dm -2 h -1 ) 15 - 30 40 - 80 (low) Carbon dioxide compensation point (ppm) 50 - 150 (Hi) 0-10 (low) 0-5 (in dark) Response to light Light saturation easily achieved No light saturation - Photosynthesis inhibited by oxygen? Yes No Yes Temperature optimum for photosynthesis 15-25 30-47 35

PowerPoint Presentation:

Internal factor: Chlorophyll Leaf resistance Demand for photosynthates Genotype Factor affecting photosynthesis:

Fate of carbohydrate products in the plant:

Fate of carbohydrate products in the plant carbon dioxide and water photosynthesis carbohydrates (e.g. glucose) mineral salts (e.g. NO 3 - , SO 4 2- ) water fatty acids glycerol amino acids

Fate of carbohydrate products in the plant:

carbohydrates (e.g. glucose) Fate of carbohydrate products in the plant carbon dioxide and water photosynthesis mineral salts (e.g. NO 3 - , SO 4 2- ) water fatty acids glycerol amino acids release energy by respiration

Fate of carbohydrate products in the plant:

carbohydrates (e.g. glucose) Fate of carbohydrate products in the plant carbon dioxide and water photosynthesis mineral salts (e.g. NO 3 - , SO 4 2- ) water fatty acids glycerol amino acids convert into starch for storage

Fate of carbohydrate products in the plant:

Fate of carbohydrate products in the plant carbon dioxide and water photosynthesis carbohydrates (e.g. glucose) mineral salts (e.g. NO 3 - , SO 4 2- ) water fatty acids glycerol amino acids change into sucrose and is transported to other parts through phloem

Fate of carbohydrate products in the plant:

Fate of carbohydrate products in the plant carbon dioxide and water photosynthesis carbohydrates (e.g. glucose) mineral salts (e.g. NO 3 - , SO 4 2- ) water fatty acids glycerol amino acids combine to form fats and oils to form cell membranes and as a food store

Fate of carbohydrate products in the plant:

Fate of carbohydrate products in the plant carbon dioxide and water photosynthesis carbohydrates (e.g. glucose) mineral salts (e.g. NO 3 - , SO 4 2- ) water fatty acids glycerol amino acids join together to become protein molecules

PowerPoint Presentation:

External Factor : CO 2

PowerPoint Presentation:

External Factor : Light

PowerPoint Presentation:

Temperature Water Nutrient External Factor:

PowerPoint Presentation:

Thank You