Part of energy lost to environment in form of heat. It is useless to plants.Chemical energy is used for formation of ATP.40-50% energy is conseved in ATP.
686 Kcal or 2870 kjoules energy liberated per glucose molecule.Continuous process Occurs in cytosol and mitochondria. Doesn't occur in viruses and dead cells.
External respiration- exchange of gases between organisms & its surrounding. In plants oxygen is obtained from stomata, lenticles of woody stem, general surface of rootInternal respiration- exchange between cell and its surrounding. In plants intracellular spaces are present for this purpose.
Floating respiration- carbohydrates and fats used as respiratory substrates.Protoplasmic respiration- proteins used, cannot continue for long time as structural and functional proteins are degraded.
Stores energy for short period.Instant source of energyMakes any amount of energy available. Mobile source of energy and reaches all parts of cell.Transfer energy from food to cell function. Donates I or 2 phosphates group and acts as phosphorylating agent.
PGAL- 3 PhosphoglyceraldehydeDHAP- dihydroxy acetone 2 molecules of 3PGAL is formed from 1 glucose molecule
IN 6TH STEP, IN animals energy liberated is utilised to form GTP. BUT later it donates its energy for formation of ATP.IN 7TH step, released H2 is accepted by FAD (FLAVIN adenine dinucleotide) to form FADH2.
The electron transport chain comprises an enzymatic series of electron donors and acceptors. At the mitochondrial inner membrane, electrons from NADH and succinate pass through the electron transport chain to oxygen, which is reduced to water
Energy obtained through the transfer of electrons (black arrows) creating an electrochemical proton gradientAllowing ATP synthase (ATP-ase) to use the flow of H+ through the enzyme back into the matrix to generate ATP from (ADP) and ip.Complex I (NADH coenzyme Q reductase; labeled I) accepts electrons from the Krebs cycle electron carrier nicotinamide adenine dinucleotide (NADH), and passes them to coenzyme Q (ubiquinone; labeled UQ), which also receives electrons from complex II (succinate dehydrogenase; labeled II). UQ passes electrons to complex III (cytochrome bc1 complex; labeled III), which passes them to cytochrome c (cyt c). Cyt c passes electrons to Complex IV (cytochrome coxidase; labeled IV), which uses the electrons and hydrogen ions to reduce molecular oxygen to water.
Complex IV donates its electron to O2 which then becomes reactive (ionised).This ionised O2 reacts with 2 protons of H and form water molecule.
Respiration ATP as currency of energy. Ultra structure of mitochondrion and its functions. Mechanism of aerobic and non aerobic respiration. Significance of respiration.
Respiration Energy is stored as organic food in plants. Energy is released when organic food is oxidised during respiration. Potential energy in food is converted into kinetic energy. Energy releasing and energy supplying process. The energy released is of two types: Heat energy Chemical energy
Definition It is an intracellular oxidation process in which complex organic substances are broken down into simpler substances with stepwise release of energy.
Raw materials Glucose OxygenProduct 38 ATPs or 686 Kcal or 2870 KJByproduct Carbon dioxide
Reaction C6 H12O6 + 6CO2 Enzymes 6H2 O + 6CO2 + 686 Kcal or 38 ATP
Overview of RespirationRespiration involves:1. Gaseous exchange External respiration Internal respiration1. Catabolic process Exergonic process Formation of water
Types of Respiration1. Aerobic Respiration The oxidation of the glucose with the help of atmospheric oxygen is called aerobic respiration.C6 H12 O6 + 6O2 6CO2 + 6H2 O + 38 ATP2. Anaerobic Respiration The partial oxidation of organic food in the absence of atmospheric oxygen is called anaerobic respiration.C6 H12 O6 2C2 H5 OH + 6CO2 + 2 ATP
Aerobic respiration Anaerobic respirationRequires molecular oxygen. Does not molecular oxygen.Respiratory substrate is fully oxidized. Respiratory substrate is incompletely or partially oxidized.End products: CO2 and H2O End products: Ethyl alcohol and CO2Exchange of gases between environment and Exchange of gases is not involved.organismMetabolic water is formed Metabolic water is not formed.Occurs partly in cytoplasm and partly in Occurs entirely in cytoplasm.mitochondria.38 ATP molecules formed from a glucose 2 ATP molecules from a glucose moleculemolecule.Involve electron transport chain. ETC not required.Process runs continuously throughout life in Occurs continuously only in someplants and animals. microorganisms. In others it takes place temporary for short period during oxygen deficiency.
Respiratory substrate The organic substances which are oxidized in cellular respiration for releasing energy are called respiratory substrate.a. Carbohydrates: glucose, fructose, starch, glycogen, sucrose.b. Fats: when carbohydrates are exhausted, fats are used as respiratory source.c. Proteins: used as respiratory substrate under starvation.
ATP ATP is energy rich organic compound which stores biologically usable form of energy. Universal carrier of chemical energy in living world. Energy currency of cells. Energy released when ATP is hydrolyzed to ADP and AMP. ATP + H2 O ADP + ip + 7.3 Kcal Energy is stored when ADP & AMP are phosphorylazed to ATP. ADP + ip ATP
ATP - Structure It is a ribonucleotide consisting of 3 components:a. Adenineb. Ribosec. Three Phosphate groups Adenine + Ribose = Adenosine. 1st Phosphate group is attached to Ribose and then to each other in a linear fashion.
ATP - Functions Storage of energy. Supply of energy. Minimization of energy wastage. Phosphate group donor
Mitochondria Double membrane bounded. Center for aerobic respiration. Present in all living eukaryotic cells. Differ in shape. (filamentous, rod shaped). 0.5- 1µm in diameter & 2-6µm in length. Colorless
Mitochondrial membraneoOuter membrane- permeable to certain solutes. Consists of 40% lipids & 60% proteins.oInner membrane- consists of 80% proteins & 20% lipids. Selectively permeable.oCristae- inner membrane infolded into the matrix. Encloses a narrow space called intracristal space. Contains enzymes for respirationoElementary particles- present on inner surface of inner membrane. Named as FI particles or Oxysomes. Range between 104-105 in a single mitochondrion.
Mitochondrial chamber Outer chamber- present between outer & inner membrane. Filled with watery fluid and few enzymes. It temporarily stores ATP molecules after synthesis. Inner chamber- central cavity of mitochondrion filled with more dense, semi fluid, granular matrix. Matrix contains enzymes, DNA, RNA, ribosomes. 2- 6 circular double stranded of molecule DNA.
Mitochondria -Functions Power house of cell Intermediate compounds Calcium storage and its release Thermogenesis Maternal inheritance
Aerobic respirationAerobic respiration is completed in Glycolysis Oxidative carboxylation (Acetylation) Krebs cycle Electron transport system
Glycolysis The sequence of reactions in which glucose (6C) is broken down into two molecules of pyruvic acid(3C). Also called as EMP pathway named after their discoverers Embden, Meyerhoff, and Paranas. 1st step in breakdown of glucose. Does not require presence of oxygen & there is no output of carbon dioxide. Occurs in cytoplasm of cell. Involves series of 10 reaction, each controlled by a specific enzyme.
The reactions are studied in three groups: Activation or phosphorylation of glucose molecule. Cleavage or fragmentation Oxidation.
Activation or Phosphorylation ofGlucose1. Phosphorylation of glucose ◦ Glucose is converted to Glucose 6- phosphate2. Isomerisation ◦ Glucose 6- phosphate isomerised to Fructose 6-phosphate.3. Second phosphorylation ◦ Fructose 6-phosphate is phosphorylased to Fructose 1, 6- diphosphate by enzyme Phosphofructokinase(PFK).
Cleavage or Fragmentation4. Cleavage ◦ Fructose 1, 6 bi phosphate is an unstable compound and splits to produce 3C compounds 3PGAL and DHAP.5. Isomerisation ◦ Glycolysis utilizes only PGAL, therefore DHAP is isomerised to 3PGAL
Oxidation6. Oxidative phosphorylation(Dehydrogenation): o 3PGAL is oxidized by removal of Hydrogen(H2) and simultaneous phosphorylation of the product resulting in 1,3 Di PGA7. ATP synthesis: o 1,3 Di PGA is converted to 3 PGA by release of one phosphate group.8. Isomerization: o Phosphate group at 3rd carbon is shifted to 2nd i.e. 3 PGA to 2PGA.
9. Dehydration : o 2 PGA loses a molecule of water and gets converted to PEPA10. ATP synthesis (formation of Pyruvic acid) o PEPA is converted to Pyruvic acid by removal of phosphate group.
Net reaction of Glycolysis C6H12O6 + 2 ADP +2 NAD+ 2 C3H4O3 + 2 ATP +2NADH + H+ Pyruvic acid Net gain of ATP 6 ATPFrom 2 NADH2 + 4ATP Directly formed - 2ATP Utilized = Net8 ATP gain
Fate of Pyruvic Acid Glucose Glycolysis Pyruvic acid O2 is used O2 is not used Aerobic Anaerobic respiration respiration
Acetylation Conversion of Pyruvic acid into Acetyl Co- A Reaction starts in cytoplasm and completes in mitochondria Co A + CO2 +Pyruvate(3C) Acetyl Co- A (2C) NAD + NADH2 Pyruvic dehydrogenas e
Kreb’s cycle Also called TCA or Citric Acid cycle. Stepwise, cyclic complete oxidation and decarboxylation of Pyruvic acid into CO2 AND H2O with release of energy. Named after Hans Krebs who traced the sequence of reactions. Takes place in matrix of mitochondria. Des not consume ATP molecules.
The reactions are as follows:1. Condensation: Acetyl Co-A (2C) combines with Oxaloacetic acid (4C) in presence of water to form Citric acid(6C).2. Isomerisation: Citric acid first dehydrates to form Cis Aconitic acid and then rehydrates to form Isocitric acid(6 C).3. Dehydrogenation: Isocitric acid oxidizes to form Oxalosuccinic acid(6C).4. Decarboxylation: With release of a CO2 Oxalosuccnic acid converts to α-Keto glutaric acid(5C).
5. Oxidative decarboxylation: α- Ketoglutaric acid oxidizes & decarboxylates and the product combines with Co-A to form Succinyl Co-A (4C).6. ATP synthesis: Succinyl Co-A is hydrolysed to Succinic acid(4C).7. Dehydrogenation: Succinic acid is oxidized to Fumaric acid (4C).8. Hydration: Fumaric acid is converted to Malic acid (4C) by addition of water. Malic acid is then oxidised to form Oxaloacetic acid(4C).
Net gain of ATP8NADH2 - 24 ATP ATP synthesis through2FADH2 - 4 ATP ETSDirect synthesis - 2 ATPTotal gain of ATP - 30 ATP
Electron Transport System Final step of aerobic respiration. Most ATP and metabolic water generated in this step. Located in inner mitochondrial member(cristae & oxysomes). Individual members are called electron carriers. Electrons from NADH and Succinate pass through the ETS to oxygen, which is reduced to water.
NADH Succinate Complex I UQ Complex IIComplex IIICytochrome cComplex IV O2
Formation of metabolic waterNADH2 or FADH2 NAD or FAD + 2H+ + 2e- 2H+ + 2e- + ½ O2 H2O
Reduced ATP through Direct Steps Total ATP coenzymes ETS ATP 1. 2 NADH2 2NADH2 X 3= 6ATP 2 ATP 8 ATPGlycolysis 2. 2 NADH2 2NADH2 X 3 = 6 ATP - 6 ATPAcetylation 3. Krebs 6 NADH2 NADH2 X 3 = 18 ATP cycle 2 ATP 24 ATP 2 FADH2 FADH2 X 2 = 4 ATP C6 H12 O6 + 6 O2 6 CO2 + 6 H2 O + 38 ATP
Significance of AerobicRespiration 1 glucose molecule produces 38 ATP molecules. Glucose molecule consists 686 k.cal energy. Of these only 277.4 k.cal energy (38 X 7.3 k.cal) is conserved in ATP. Remaining energy is lost as heat energy. Efficiency of this respiration is 40%.
Anaerobic respiration The partial incomplete oxidation of organic food in the absence of atmospheric oxygen is called Anaerobic respiration. Organisms performing anaerobic respiration are called anaerobes. In micro organisms it is known as fermentation. No exchange of gases. Only 2 ATP molecules are formed.
Mechanism It is completed in 3 main steps. 1. Glycolysis 2. Decarboxylation 3. Reduction
Glycolysis First step is similar to glycolysis of aerobic respiration.C6H12O6 + 2ADP +2NAD+ 2C3H4O3 +2 ATP+2NADH+H+
Decarboxylation Pyruvic acid is decarboxylated to form Acetaldehyde (2C) and CO2 by enzyme pyruvate decarboxylase. Pyruvate Decarboxylas2CH3CO COOH e 2CH3CHO + 2CO2 Pyruvic acid Acetaldehyde
Reduction Acetaldehyde is reduced to Ethyl Alcohol by NADH2 formed in Glycolysis with the help of enzyme Alcohol Dehydrogenase. Alcohol Dehydrogena seAcetaldehyde Ethyl Alcohol
Significance of Respiration Release of energy Synthesis of ATP Stepwise release of energy Growth and development Energy for biosynthesis Role of intermediates Balance of CO2 & O2 Fermentation