2Relationship Between Photosynthesis and Respiration Products of photosynthesis are reactants in respiration
33.7 Assessment Statements Define cell respiration.State that, in cell respiration, glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP.Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP.Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP.
43.7.1 Define cell respiration The break-down of energy containing molecules into products and energy that can be used by the organismGlucose is a very energetic molecule. Releasing all of that energy at once would be too much to be useful (think burning a sugar).Therefore, respiration involves a gradual, step-wise release of energy in smaller increments.
5Boardworks A2 BiologyRespirationWhat is respiration?Respiration is the process by which organisms extract the energy stored in complex molecules and use it to generate adenosine triphosphate (ATP).In this way they obtain energy to fuel their metabolic pathways.ATP provides the immediate source of energy for biological processes such as active transport, movement and metabolism.ATP
6Adenosine triphosphate Boardworks A2 BiologyRespirationAdenosine triphosphateATP contains a sugar (ribose), a base (adenine) and three phosphate groups.adenineribosephosphatesWhen ATP is hydrolyzed to form ADP and inorganic phosphate, 30.5 kJ of energy are released.+30.5 kJATPH2OADPinorganic phosphate
7Why ATP?Biological systems transfer the energy in glucose to ATP because unlike glucose…glucoseATPATP releases its energy instantly in a single reaction.The hydrolysis of ATP releases a small amount of energy, ideal for fueling reactions in the body.
8Phosphorylation: 2 ways to make ATP Boardworks A2 BiologyRespirationPhosphorylation: 2 ways to make ATPThe addition of an inorganic phosphate group (Pi) to a molecule like ADP is called phosphorylation. ADP is phosphorylated during respiration.Two types of phosphorylation occur during respiration:1. Substrate-level: glycolysis & Krebs cycleA single reaction involving the direct transfer of a phosphate group from a carbon (organic) molecule to ADP ATP.Does not produce much ATP (2-4)2. Oxidative: electron transport chainA series of oxidation reactions that produce sufficient energy to form ATP from ADP and phosphate. (Pi is added to ADP).Produces a lot of ATP (34-38)
9Oxidation & ReductionOxidation is the loss of electrons or H atoms from an atom or molecule. Oxidized atoms or molecules have less energy than they had before they were they were oxidized. Reduction is the gain of electrons.Reduced atoms or molecules have more energy than before they were reduced.
10OIL RIG Oxidation Is Loss of electrons Reduction Is Gain of electrons
11Redox Reactions Reduction-Oxidation The main chemical reaction in cellular respiration that involves the transfer of electrons from one reactant to anotherRedox reactions are comprised of both oxidation and reduction reactions that always go together
12How Redox Reactions Work Oxidation ReactionThe loss of electrons from one reactant.Reduction ReactionThe addition of electrons to one reactant
13Examples of Redox Reactions in Respiration Glycolysis – the splitting of glucose in the first stage of cellular respirationSeveral reactions in citric acid cycle
14Where does respiration occur? Boardworks A2 BiologyRespirationRespiration occurs in all living cells. In eukaryotes the early stages of respiration occur in the cytoplasm. The later stages of respiration are restricted to the mitochondria.Mitochondria contain highly folded inner membranes that hold key respiratory proteins (including the enzyme that makes ATP) over a large surface area.Mitochondria provide an isolated environment to maintain optimum conditions for respiration.Mitochondria have their own DNA and ribosomes, so can manufacture their own respiratory enzymes.
15State that, in cell respiration, glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP.= ATP
16An overview of respiration Boardworks A2 BiologyRespiration7
17The first stage of respiration: glycolysis Boardworks A2 BiologyRespirationThe first stage of respiration: glycolysis
18Glycolysis Glycolysis occurs in the cytoplasm One glucose molecule is broken into two pyruvate molecules in glycolysis (pyruvic acid)Fate of pyruvates depends on presence/absence of oxygen
19Glycolysis Animations Glycolysis (Smith)How Glycolysis Works (McGraw Hill)Quiz
21Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP.ATP
22An overview of respiration Boardworks A2 BiologyRespiration7
23Boardworks A2 BiologyRespirationTypes of respirationDuring aerobic respiration, a respiratory substrate, e.g. glucose, is split in the presence of oxygen to release carbon dioxide and water. A large number of ATP molecules are produced, releasing the energy from the glucose.C6H12O O2 6 CO H2O ATPIn anaerobic respiration, glucose is converted (in the absence of oxygen) to either lactate or ethanol. The ATP yield is low.C6H12O6 2 C2H5OH CO ATPethanolC6H12O6 2 C3H6O ATPlactate23
24Anaerobic Respiration Occurs without oxygenWhere does it happen?Occurs in cytoplasm of cellTwo typesAlcohol fermentationLactic acid fermentation
25Alcohol Fermentation Occurs in bacteria (and yeast) Uses glycolysis to produce pyruvateProduces CO2, ethanol and energy
26Lactic Acid Fermentation Occurs in humans (or anything with muscles)Uses glycolysis to produce pyruvateProduces lactic acid and energy
27FermentationDepending on the type of organism involved there are two types of fermentation: alcohol fermentation (in yeasts and some bacteria) and lactic acid fermentation (in many micro-organisms and animal muscle cells).
29Boardworks A2 BiologyRespirationCoenzymesCoenzymes are molecules that bind with a specific enzyme or substrate, helping to catalyze a reaction. Breaking the bonds between coenzyme and product after a reaction is crucial, otherwise coenzyme concentration will drop, limiting respiratory rate.substrateenzymecoenzymeThree major coenzymes are used in respiration:NAD (nicotinamide adenine dinucleotide)CoA (coenzyme A)FAD (flavine adenine dinucleotide)
30Boardworks A2 BiologyRespirationNAD, FAD and coenzyme ANAD can accept a hydrogen molecule, forming reduced NAD (NADH).nicotinamideNAD+ + 2HNADH + H+adenineThis is used to regenerate ADP in the electron transport chain (ETC).riboseNADCoenzyme A aids the transition between glycolysis and the Krebs cycle, by converting pyruvate to acetyl coenzyme A.FAD, like NAD, can accept hydrogen to form reduced FAD (FADH2).
31Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP.=ATP
34Aerobic Respiration: Part 1 Glycolysis One glucose molecule is broken into two pyruvate molecules in glycolysis /pyruvic acidGlycolysis occurs in the cytoplasmThese pyruvates enter the mitochondria by active transport via a membrane protein
35Aerobic Respiration: Part 2 Link Reaction Once inside, the pyruvate is converted to acetyl CoA in the link reactionThis link reaction forms NADH and CO2Acetyl CoA then enters the citric acid cycle
36Animations Glycolysis (Smith) Krebs cycle (Smith) Electron Transport System and ATP Synthesis (McGraw Hill)How Glycolysis Works (McGraw Hill)How the Krebs Cycle Works (McGraw Hill)How the NAD+ Works (McGraw Hill)
37Aerobic Respiration: Part 3 Citric Acid Cycle / Krebs Cycle FAD / NAD+ accepts hydrogen and a high-energy electron to form NADH / FADH2;These electron carriers (FADH2 / NADH) donate electrons to electron transport chain
38Aerobic Respiration: Part 4 Oxidative Phosphorylation These electrons transfer their energy to member proteins (protein pumps) and actively pump protons (hydrogen ions) across inner membraneOxygen is the final electron acceptor and produces water as a “waste product”The build up of protons (proton gradient) in the intermembrane space of the mitochondria through ATPase; (this is called chemiosmosis)Producing the ATP involves adding a phosphate to ADP. This is PhosphorylationProduces 36/ 38 ATP (per glucose)
39Aerobic Respiration: Part 4-A Electron Transport These electrons transfer their energy to member proteins (proton pumps) and actively pump protons (hydrogen ions) across inner membraneOxygen is the final electron acceptor and produces water as a “waste product”
41Aerobic Respiration: Part 4-B Chemiosmosis Protons build up (making a proton gradeint) in the intermembrane space of the mitochondrionGradient potential is then turned into ATP as protons flow into matrix of mitochondrion through ATPase / ATP synthase
43Animations Glycolysis (Smith) Krebs cycle (Smith) Electron Transport System and ATP Synthesis (McGraw Hill)How Glycolysis Works (McGraw Hill)How the Krebs Cycle Works (McGraw Hill)How the NAD+ Works (McGraw Hill)