Respiration: - is the process by which chemical energy in organic molecule is released by oxidation. ATP: - is the energy currency of a cell. • Is a nucleotide that has energy rich bonds joining the two terminal phosphate groups to the nucleotide •It is described as a phosphorylated nucleotide •ATP molecule consist of :- A nitrogenous base (Adenine), A pentose sugar (deoxyribose) & A phosphate group. Some process that require ATP energy • Active transport • Muscle contraction •Conduction of nerve impulse • Synthesis of macro molecules •Intial stage of cellular respiration How ATP is produced in a cell The formation of ATP by ADP and Pi involves an enzyme called ATP synthase. There are two main path ways in which respiration can produce ATP. These are Aerobic Pathway:- occurs in the presence of oxygen Anaerobic Pathway:- occurs in the absence of oxygen How ATP is produced in aerobic respiration There are two main ways of ATP production in aerobic path way these are Substrate level Phosphorylation: - When another molecule (substrate) is able to transfer phosphate group directly to ADP. ATP Synthase is not involved. 10%of ATP is produced It occurs during glycolysis and kreb cycle Oxidative Phosphorylation:-oxygen dependent production of ATP Uses ATP Synthase enzyme 90%of ATP is produced It involves oxidation of organic molecules Stages of aerobic respiration of glucose: There are four main stages of aerobic respiration of glucose these are : Glycolysis Link reaction Kreb cycle Electron transport chain and chemiosmosis Glycolysis: - it means that glucose splitting • It involves oxidation of glucose to pyruvate • It takes place in the cytosol of cytoplasm • It is the first stage of cellular respiration • It occurs in the absence of oxygen Link reaction: -it is involved in the presence of oxygen It is the transition between glycolysis and kreb cycle A molecule of pyruvate react with a molecule of co enzyme A (COA) to form a molecule of acetyl co enzyme A . It involves three main steps these are A carboxyl group is removed as CO2 by pyruvate decarboxylase A redox reaction occur where 2NAD + is reduced to 2NADH and pyruvate is oxidized to acetate A sulfur containing COA binds to acetate group to form acetyl –COA. Kreb cycle: - It is called Tricarboxylic acid cycle The path way begins when the acetyl co enzyme A reacts with a four carbon containing compound called oxaloacetate to form a six carbon containing compound called citrate. In kreb cycle one cycle produces two carbon dioxide , three reduced NAD, one reduced FAD and one ATP Two pyruvate enter the kreb cycle from one glucose molecule Two citric acid cycle occur for one glucose molecule Involves the following main steps Formation of Citrate The condensation of acetyl-CoA with oxaloacetate produces citrate. This reaction is catalyzed by citrate synthase.Once oxaloacetate is joined with acetyl-CoA, a water molecule attacks the acetyl leading to the release of coenzyme A from the complex. Acetyl CoA(2C) + Oxaloacetate(4C) →→→→→Citrate (6C) Oxidative decarboxylation of citrate Catalyzed by dehydrogenase enzyme and releases/ removes a molecule of CO2 Produces a 5-carbon compound called α-Ketoglutarate. Oxidative decarboxylation of α-Ketoglutarate A molecule of CO2 is released and a 4-carbon compound (Succinyl CoA) is formed.Catalyzed by alpha-ketoglutarate dehydrogenase.A molecule of NAD is reduced while α-Ketoglutarateis oxidized. Regeneration of oxaloacetate • Succinic CoA undergoes several molecular transformations to produce oxaloacetate. At this step the following two vital processes (events) take place. Reduction of NAD and FAD During the course of the cycle, the cell harvests: One ATP Three reduced NAD/NADH/ molecules One FADH2 ❖ For every glucose that enters cellular respiration, the Krebs cycle runs twice becauseglucose gets broken down to two pyruvates, which become two Acetyl Synthesis of ATP by substrate level phosphorylation Electron transport chain •The final stage of aerobic respiration that generates much amount of ATP. •Takes place on the inner mitochondrial membrane. •The inner membrane is arranged into folds (cristae), which increases the surface area available for the transport chain. •Releases the energy stored within the reduced hydrogen carriers in order to synthesize ATP. •Involves chemiosmosis and oxidative phosphorylation. Consists of the following vital steps/processes. 1.Dehydrogenation of NADH and FADH2 •The hydrogen carriers (NADH and FADH2) are oxidized and release high energy electrons and protons. •NADH dehydrogenase oxidizes NADH and Ubiquinone oxidizes FADH2 .The electrons are transferred to the electron transport chain, which consists of several Transmembrane carrier proteins. •As electrons pass through the chain, they lose energy – which is used by the chain to pump protons (H+ ions) from the matrix. •The accumulation of H+ ions(protons) within the intermembrane space creates an electrochemical gradient (or a proton motive force). 2. Chemiosmosis and ATP synthesis •The proton motive force will cause protons(H+ ions) to move down their electrochemical gradient and diffuse back into matrix. •ATP synthase uses the subsequent diffusion of protons (chemiosmosis) to synthesize ATP. •As the protons(H+ ions) move through ATP synthase they trigger the molecular rotation of the enzyme, synthesizing ATP. •Aerobic respiration involves four stages: glycolysis, a transition reaction that forms acetyl coenzyme A, the citric acid (Krebs) cycle, and an electron transport chain and chemiosmosis. •During various steps in glycolysis and the citric acid cycle, the oxidation of certain intermediate precursor molecules causes the reduction of NAD to NADH + H and FAD to FADH. NADH and FADH then transfer protons and electrons to the electron transport chain to produce additional ATPs by oxidative phosphorylation. •The electron transport chain consists of a series of electron carriers that eventually transfer electrons from NADH and FADH to oxygen. These include: •NADH dehydrogenase •Ubiqinone, and •Cytochrome complex •During aerobic respiration, the last electron carrier in the membrane transfers 2 electrons to half an oxygen molecule (an oxygen atom) that simultaneously combines with 2 protons from the surrounding medium to produce water as an end product. •The summary equation for aerobic respiration is: C6H12O6 + 6O2 ➞ 6H2O + 6CO2 + 36ATP Respirometer A device used to measure the rate of respiration of a living organism by measuring its rate of exchange of oxygen and/or carbon dioxide. Allows investigation into how factors such as age, or chemicals affect the rate of respiration. Designed to measure respiration either on the level of a whole animal or plant or on the cellular level. The living specimen (e.g. germinating seeds or invertebrate organism) is enclosed in a sealed container. Carbon dioxide production can be measured with a data logger or by PH changes if the specimen is immersed in water. When an alkali is included to absorb CO2, oxygen consumption can be measured as a change in pressure within the system The pressure change can be detected with a data logger or via use of a U-tube manometer. Factors which may affect respiration rates include temperature, hydration, light (plants), age and activity levels An increase in carbon dioxide levels will indicate an increase in respiration (CO2 is a product of aerobic respiration). A decrease in oxygen levels will indicate an increase in respiration (O2 is a requirement for aerobic respiration). Anaerobic Respiration Type of respiration through which cells can break down sugars to generate energy in the absence of oxygen. Is in contrast to the highly efficient process of aerobic respiration, which relies on oxygen to produce energy. Molecular oxygen is the most efficient electron acceptor for respiration, due to its high affinity for electrons. However, some organisms have evolved to use other final electron acceptors, and as such, can perform respiration without oxygen. Takes place in the cytoplasm of both prokaryotic and eukaryotic cells. Is a less efficient method of generating cellular energy. Produces less ATP for each sugar molecule digested than aerobic respiration. Can be described as fermentation. The types of anaerobic respiration are as varied as its electron acceptors. Important types of anaerobic respiration include: Lactic acid fermentation Glucose is split into two molecules of lactic acid to produce two ATP. Occurs in certain types of bacteria and some animal tissues, such as muscle cells. ( C6 H12 O6 (glucose) + 2 ADP + 2 Pi 2 C3 H6 O3 + 2ATP) Alcoholic fermentation Glucose is split into ethanol or ethyl alcohol. Also produces two ATP per sugar molecule. Releases CO2 as a byproduct. Occurs in yeast and even in some types of fish, such as goldfish. C6 H12 O6 (glucose) + 2 ADP + 2 Pi→ 2 C2 H5 OH (ethanol) + 2 CO2 + 2 ATP Cori cycle 1..How many moles of ATP will be generated as a result of FADH2 in actively respiring mitochondria? 2. In a bacterium what is the net production of ATP molecules from a four glucose molecule in the absence of oxygen. 3.How many ATP molecules are synthesized directly in the Krebs citric acid cycle if you supply an aerobic cell with 20 pyruvic acid molecules? 4. What will be the net amount of ATP that is produced when a molecule of pyruvate oxidized into acetyl COA? 5. What net amount of ATP will be produced through oxidative phosphorylation from 3 molecules of glucose in actively respiring mitochondria? 6. How much ATP can be produced if 5 FADH2 and 12NADH give their electrons to the electron transport system in the presence of oxygen? 7.How many Krebs cycles and FADH2 can be produced when 4 glucose molecules undergo full respiratory process? 8.Work out the grand total ATP molecule produced from 20 mole of glucose during chemiosmotic phosphorylation in a certain liver cell. 9.What effect would be resulted whether NADH or FADH is used as an initial hydrogen donor in the carrier chain during aerobic respiration? 10.How many molecule of ATP is gained by a cell during the process of glycolysis from 12 molecules of glucose? • is the process by which light energy is converted into chemical energy of organic molocules. • It involves transduction of light energy into chemical energy. • Light energy is absorbed by a pigment molecule known as chlorophyll. • It takes place inside the chloroplast • it is carried out by a groups of organisms called photo autotrophs such as plants, algae and photosynthetic bacterias. • Transduced means conversion of energy from one form to another Structures and functions of chloroplast Chloroplast is an organelle which enclosed by a double membrane. it consist of major parts Grana:- is the sack of thylakoids where the light dependent reaction of photosynthesis takes place. stroma :- is a part wher the light independent reaction (calvin cycle)of photosynthesis takes place. thylakoids flattened sacs inside a chloroplast on which light-dependent reactions of photosynthesis take place Photosystems biochemical mechanism by which chlorophyll absorbs light energy. photosystem I photosystem in photosynthetic light reactions discovered before photosystem II. It involves two major stages these are Light dependent stage (Light reaction):- is the stage on which light energy is directly required. 12H2O + 12NADP+ +18ADP + 18Pi → 6O2 + 12NADPH + 12H+ + 18ATP Light independent (Dark reaction):- light energy is not required. 12NADPH + 12H+ + 18ATP + 6CO2 → C6H12O6 + 12NADP+ + 18ADP + 18Pi +6H2O Both stages of Photosynthesis occur at the day time when there is light.The light-dependent reactions use light energy to ‘drive’ the synthesis of two molecules that will, in turn, drive the light independent reactions. These two molecules are: •ATP – this provides the energy for the reactions, and •reduced NADP – this provides the hydrogen ions for a key reduction reaction. NADP is very similar to NAD that is used in respiration and it has the same function – transporting hydrogen ions. Is the process by which electron energized by photons (light particles) contribute their energy to the phosphorylation o ADP in synthesizing ATP. There are two forms of phosphorylation that are used in the light dependent reaction. these are:Is the simplest route of light dependent reaction in which only photosystem I is involved. The pathway is cyclic because excited electrons originate from P700 at the reaction center and return to P 700. No oxygen and no reduced NADP are formed The whole Photosynthetic units are not involved. it is known as back to back phosphorylation from PSI to PSI for the production of ATP. No NADPH is produced. it is not the basis for photosynthesis because NADPH is necessary for CO2 tobe reduced to carbohydrate . Is the most common type of photophosphorylation Both photosytems are involved There is one way flow of electrons from water to NADP+ It yeilds 2 ATP and 1 NADPH photosynthetic unit an arrangement of molecules capable of carrying out all the reactions in the light-dependent stage of photosynthesis. In cyclic and non-cyclic photophosphorylation, ATP is produced because: • there is an accumulation of protons (hydrogen ions) in the interior of a thylakoid • this creates a concentration gradient between the thylakoid interior and the stroma of the chloroplast • protons move down this concentration gradient, through ATP synthase, causing the rotor to spin, just as in mitochondria during respiration. The light-independent reactions of photosynthesis occur in the stroma of the chloroplasts. photolysis means light-dependent splitting of water Features Non cyclic photo phosphorylation cyclic photo phosphorylation path way of electrons Non cyclic cyclic first electron donor Water PSI (P700) last electron acceptor NADP PSI(P700) products ATP, NADPH and Oxygen ATP only photosystem involved PSI and PSII PSI Reaction centre molecule are molecules where light-dependent reactions begin. NADP reductase are enzymes that makes the NADP to react with Hydrogen ions inorder to form a reduced NADP (NADPH). Photosystem II is active upto a maximum of 680nm wavelength of light. Photosystem I is active with in a maximum of 700nm wavelength of light. The efficiency of Photosynthesis increases as the intensity of light increases upto a limiting value. Features Light dependent Light independent Takes place In the Thylakoid membrane in the stroma of chloroplast Light requirement Requires light Do not require light reaction process • Photolysis of water • Cyclic and non cyclic photo phosphorylation • CO2 fixation • Reduction of ATP and NADPH • REgeneration of RUBP Raw materials Light energy, Water, ADP and NADP CO2, RUBP, ATP and NADPH End product 18ATP, 12NADPH,6O2 18ADP+18Pi, 12NADP, C6H12O6,and RUBP overall chemical equation 12H2O -----→24H++ 6O2 3CO2+24H++18ADP+18 Pi ---→ C6H12O6+ 6H2O • carbon dioxide reacts with ribulose bisphosphate (RuBP) – a five-carbon compound in the stroma; the reaction is catalysed by the enzyme Rubisco. • two molecules of the three-carbon compound GP are formed from this reaction. • each molecule of GP is converted to TP (triose phosphate – another three-carbon compound); this is a reduction reaction using hydrogen ions from reduced NADP and energy from ATP • some of the TP formed is used to regenerate the RuBP (ATP is again required) whilst some is used to form glucose and other useful organic compounds. The amount of light in an environment. Cold bright day (arctic area):- High light intensity but low temprature which affect the enzymatic activity. On warm cloudy day:- Low light intensity but high temprature. Low light intensity affects the number of electrons excited in the light dependent reaction. On warm sunny day:- High light intensity and high temprature. The rate of photosynthesis is affected since the stomatal pores close and sufficient amount of CO2 donot enter the chloroplast. At low concentration of CO2 the rate of photosynthesis declines. The change in temprature affects enzymatic activity that regulate the rate of photosynthesis. Photosynthesis takes place efficiently in red and blue wave length than others. Low chlorophyll concentration can result in deacrease the rate of photosynthesis. The lack of watr affect the rate of photosynthesis even it result wilting and drying of the plant. C3 photosynthesis and photorespiration:- It is also known as Calvin cycle. It takes place in the stroma of chloroplast. Crop plants that are grown in temperate areas (such as peas and carrots) are C3 photorespiration is the process involving the oxidation of carbon it occurs in organelles of chloroplast, peroxisomes and mitochondria. Ribulose bisphosphate + Oxygen --Rubisco--→ GP + Phosphoglycolate They have broad leaves. Their palaside cells are nearest to the upper surface of the upper surface of the leaf to bsorb more light. Their stomata are open to allow the entry of CO2, but closed if water loss is too high on a hot day. Spongy mesophyll has air spaces that allow easy diffusion of CO2 and oxygen. Photorespiration reduces the efficiency of photosynthesis for several reasons, including: • the carbon is oxidised, which is the reverse of photosynthesis – the reduction of carbon to carbohydrate • the ribulose bisphosphate must be resynthesised and the phosphoglycolate removed • ATP is used in the resynthesis of RuBP. Unlike C3 plant the first compound formed in the light independent reaction is C4 compound. The light independent reaction takes place in mesophyll cells. C4 photosynthesis include plants that grow in tropical areas like Ethiopia (such as maize, crabgrass, wheat, sorghum and sugar cane). C4 photosynthesis is most efficient in conditions of: • low carbon dioxide concentration • high light intensity • high temperature CAM uses PEP carboxylase to fix CO2 at night time. They are mostly grow in desert and arid regions of the world. It includes plants like pineapple, cactus. Feature C3 C4 CAM Leaf structure Bundle sheath cell Bundle sheath cell Large vacuole in lacking chloroplast having chloroplast mesophyll cell and no thylakoid Enzyme used to fix CO2 Rubisco PEPco PEPco Optimum temperature 15-25 30-40 35 Optimum CO2 concentration 700ppm 400ppm 400ppm Mesophyll cells Mesophyll cells Mesophyll cells Mesophyll cells Bundle sheath cells Bundle sheath cells Fixation of CO2 Calvin cycle CAM photosynthesis is effective in desert plants because it : separates the light-dependent and light-independent stages in time; the leaves only open their stomata to allow the light-independent reactions to take place during the night, saving precious water. Prepared By Thank You !!!