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Topic 8 : Cell respiration and Photosynthesis AND OPTION C: Cells and Energy C1: Proteins C.1.1:Primary Structure C.1.1: Secondary Structures Alpha Helix Beta Pleated Sheet protein ribbonprotein ribbon 7.5.1: Quaternary Structure C.1.1: Conjugated Protein C.1.2 C.1.2: Globular Protein C.1.2:Fibrous Protein C.1.3 Polar Amino Acid C.1.3: Non-polar amino acids C.1.3 C.1.3 C.1.3 C.1.4: Functions of proteins (other than membrane proteins) C2: Enzymes C.2.1 C.2.2 C.2.3 C.2.4 C.2.4 Prontosil is a competitive inhibitor that is used as an antibiotic because it inhibits folic acid synthesis in bacteria. Nerve gases like Sarin function by inactivating the enzyme ethanoyl (acetyl) cholinesterase. C.2.5 7.6.5 C3, 8.1: Cellular Respiration C.3.1, 8.1.1:Oxidation/Reduction STATE: oxidation involves the gain of oxygen reduction involves the loss of oxygen C.3.1, 8.1.1: Oxidation/Reduction STATE: oxidation involves loss of electrons reduction involves gain of electrons C.3.1, 8.1.1:Oxidation/Reduction STATE: oxidation involves loosing hydrogen reduction involves gaining hydrogen C.3.1, OiL RiG ??????? ( OiL RiG only applies to electrons and hydrogen) (Aerobic)Cellular Respiration Formula GLUCOSE + OXYGEN CARBON DIOXIDE + WATER + ATP C6H12O6 + 6O2 6CO2 + 6H2O C.3.2, 8.1.2: Outline the process of glycolysis, including phosphorylation, lysis, oxidation and ATP formation 8.1.2: Glycolysis Adenosine triphosphate NAD: Electron Carrier NAD+ = oxidised form NADH + H + = reduced form NAD+ + 2H → NADH + H+ 2 2 2 2 Pyruvate Pyruvate Oxidation of triose phosphate Reduction of NAD + to NADH + H + From one glucose molecule in glycolysis: 2 x ATP (net) 2 X (NADH + H+) 2 X pyruvate IB Question: Outline the process of glycolysis. [5] occurs in cytoplasm; hexose is phosphorylated using ATP; hexose phosphate is split into two triose phosphates; oxidation by removal of hydrogen; (do not accept hydrogen ions/protons) conversion of NAD to NADH (+H+); net gain of two ATP / two ATP used and four ATP produced; pyruvate produced at the end of glycolysis; [5 max] Accept glucose/fructose/6C sugar instead of hexose. Accept 3C sugar/glyceraldehyde instead of triose. NAD: Nicotinamide adenine dinucleotide, abbreviated NAD A co-enzyme is a non-protein chemical compound that is loosely bound to a protein and is required for the protein's biological activity. C.3.3, 8.1.3: Draw and label a diagram showing the structure of a mitochondria as seen in electron micrographs Mitochondrion inter C.3.4, 8.1.4: Explain aerobic respiration, including the link reaction, the Kreb’s cycle, the role of NADH + H+, the electron transport chain and the role of oxygen IB Question: Draw and label a mitochondrion as seen in electron micrographs. [4] M08/4/BIOLO/HP2/ENG/TZ2/XX Award [1] for each of the following clearly drawn and correctly labelled. outer membrane; inner membrane – folded into thin cristae; cristae – shown as thin; matrix; intermembrane space – shown as thin; (70S) ribosomes; ATP synthase – shown on the inner membrane surface; (naked) loop of DNA; [4 max] Pyruvate decarboxylation (Oxidative decarboxylaytion) Oxidation of pyruvate From one pyruvate molecule in the link reaction the products are: 1 x (NADH + H+) 1 x CO2 1 x acetyl CoA The Kreb’s Cycle occurs in the matrix of the mitochondria C.3.5, 8.1.4: Chemiosmosis ADP joins with inorganic phosphate IB QuestionExplain the process of aerobic cell respiration after glycolysis has occurred. [8] pyruvate produced by glycolysis; pyruvate enters mitochondrion/mitochondria; pyruvate loses CO2 in link reaction; and NADH + H+; with formation of acetyl CoA; to take part in Krebs cycle; where two CO2 are produced (per molecule of pyruvate); one ATP from ADP + Pi; along with (three) NADH + H+ (and one FADH2); NADH + H+ provide electrons circulating in the electron transport chain on the inner mitochondrial membrane; allowing H+ to accumulate in the intermembrane space; and come back to the matrix through ATP synthase/synthetase to produce ATP (by chemiosmosis); presence of O2 required as the final electron acceptor for the electron transport chain; producing water with H + ; [8 max] C.3.5, 8.1.5: Explain oxidative phosphorylation in terms of chemiosmosis Oxidative phosphorylation: Oxidative phosphorylation: The process in cell metabolism by which respiratory enzymes in the mitochondria synthesize ATP from ADP and inorganic phosphate using the energy released by the oxidation of NADH and FADH2 by molecular oxygen. The coupling of the movement of electrons down the electron transport chain with movement of hydrogen ions through ATP synthase to generate ATP which occurs in the mitochondria of eukaryotic cells during aerobic cellular respiration. Chemiosmosis: the diffusion of hydrogen ions (protons) across the biological membrane via the ATP synthase. As the hydrogen ions diffuse (through the ATP synthase) energy is released which is then used to drive the conversion of ADP and inorganic phosphate to ATP. Oxidative phosphorylation IB Question: Describe the function of oxygen in oxidative phosphorylation [2] oxygen is the final acceptor of electrons/protons/; water is formed / oxygen is reduced; in the (mitochondrial) electron transport chain; (aerobic respiration) increases yield of ATP; [2 max] H IB Question: Explain how chemiosmosis assists in ATP production during oxidative phosphorylation. [9] occurs during aerobic respiration; oxidative phosphorylation occurs during the electron transport chain; hydrogen/electrons are passed between carriers; releasing energy; finally join with oxygen (to produce water); occurs in cristae of mitochondria; chemiosmosis is the movement of protons/hydrogen ions; protons move/are moved against their concentration gradient; into the space between the two membranes; protons flow back to the matrix; through the ATP synthase/synthetase (enzyme); energy is released which produces more ATP/combines ADP and Pi; [9 max] 8.1.6: Explain the relationship between the structure of the mitochondrion and its function Mitochondrion Structure Matrix Inter-membrane space Cristae Function of structure The matrix is the mitochondrion’s cytoplasm. It is the fluid contained inside the inner membrane. The matrix contains enzymes for the Krebs cycle. The small intermembrane space is in-between the inner and outer membrane of a mitochondrion. It functions to store protons, which are then used to make ATP as they flow down a concentration gradient. Cristae are infoldings of the inner membrane, which is the location of the electron transport chain of cell respiration. The cristae increase surface area of the inner membrane; thus increasing the rate of ATP formation. Cellular Respiration: Overview PHOTOSYNTHESIS CARBON DIOXIDE +WATER GLUCOSE + OXYGEN 6CO2 + 6H2O C6H12O6 + 6O2 Photosynthesis Photosynthesis • Chloroplast - Electron micrograph 8.2.1: Draw and label a diagram showing the structure of a chloroplast as seen in electron micrographs IB Question: Draw a labelled diagram of the structure of a chloroplast as seen with an electron microscope. [4] M09/4/BIOLO/HP2/ENG/TZ1/XX Award [1] for each of the following clearly drawn and correctly labelled. Label lines must be unambiguous in terms of what they are indicating. double/inner and outer membrane/envelope – shown as two concentric continuous lines close together; granum/grana – shown as a stack of several disc-shaped subunits; (intergranal) lamella – shown continuous with thylakoid membrane; thylakoid – one of the flattened sacs; stroma; (70S) ribosomes/(circular) DNA / lipid globules / starch granules / thylakoid space; [4 max] 8.2.2: STATE: Photosynthesis consists of the Light Dependent Reaction and the Light Independent Reaction 8.2.3: Explain the light-dependent reaction and 8.2.4: Explain oxidative photophosphosphorylation in terms of chemiosmosis 1 2 3 4 5 6 7 8 9 ADP joins with inorganic phosphate 10 Non Cyclical andCyclical Photophosphorylation IB Question: Outline the light-dependent reactions of photosynthesis. [6] M09/4/BIOLO/HP2/ENG/TZ2/XX (chlorophyll/antenna) in photosystem II absorbs light; absorbing light/photoactivation produces an excited/high energy/free electron; electron passed along a series of carriers; reduction of / generates ; NADP NADPH H absorption of light in photosystem II provides electron for photosystem I; photolysis of water produces ; 2 H /O called non-cyclic photophosphorylation; in cyclic photophosphorylation electron returns to chlorophyll; generates ATP by pumped across thylakoid membrane / by chemiosmosis / through ATP synthetase/synthase; [6 max] H 8.2.5: Explain the Light independent reaction (calvin cycle) CARBON FIXATION RuBP carboxylase CARBON FIXATION Glycerate -3phosphate REDUCTION of gylcerate 3phosphate Triose phosphate (TP) Regeneration of RuBP IB QuestionExplain the light-independent reactions. [8] CO is fixed to form a carbohydrate; ATP and NADPH produced in light dependent reactions used in light independent reactions; glyceraldehydes / three-carbon sugar; occurs in stroma of chloroplast; ribulose bisphosphate carboxylase (Rubisco) catalyzes attachment of 2 CO to (five-carbon sugar) ribulose bisphosphate (RuBP); (unstable six-carbon intermediate) forms two molecules of glycerate-3-phosphate; each (of two) glycerate-3-phosphate then receives one phosphate from ATP; each (of two) phosphorylated glycerate-3-phosphate is reduced by NADPH H ; result is (two molecules of) glyceraldehyde phosphate/triose phosphate (TP); for every six molecules of glyceraldehyde phosphate one goes to form glucose/ glucose phosphate; remaining molecules reorganized to RuBP; reorganization requires ATP; RuBP allows cycle to start again; [8 max] IB Qustion: Outline the conversion of light energy to chemical energy in photosynthesis. [6] light energy absorbed by chlorophyll (photo) activates photosystems; electron in chlorophyll/photosystem activated/excited / raised to higher energy level; photolysis of water replaces excited electrons; energy passed through electron carriers/ETS; hydrogen/high energy electrons reduce NADP+ ; photophosphorylation by chemiosmosis; (some) H+/protons pumped into thylakoid spaces; proton gradient is created; energy released as protons pass through ATP synthetase; ATP produced; correct reference to (non cyclic or cyclic) photophosphorylation; glucose/sugar/monosaccharide produced in Calvin cycle; [6 max] Credit can be given for any of these points shown on a correctly drawn and labelled diagram. C.4.6 8.2.6: Explain the relationship between the structure of the chloroplast and its function Structure Stroma Thylakoids Thylakoid space Function of structure The viscous fluid of the stroma provides enzymes for the Calvin cycle. The thylakoids provide a large surface area for light absorption and the reactions of photosynthesis. The small center of each thylakoid provides space (the thylakoid space) for the accumulation of protons (H+), used to make ATP. C.4.7, 8.2.6: : Explain the relationship between the action spectrum and the absorption spectrum photosynthetic pigments in green plants C.4.8, 8.2.8: Explain the concept of limiting factors in photosynthesis, with reference to light intensity, temperature and concentration of carbon dioxide C.4.8, 8.2.8 IB Question: Outline the cellular locations of different named processes in both photosynthesis and cell respiration. [6] photosynthesis: [3 max] chloroplasts/photosystems: for light absorption/photosynthesis; stroma: light-independent reactions / Calvin cycle; thylakoid membranes of chloroplast: chemiosmosis / photophosphorylation/light dependent reactions; thylakoid space: build up H+ concentration gradient; inner membrane of thylakoid: electron transfer; inner membrane: ATP synthesis; cell respiration: [3 max] mitochondria: for ATP production/aerobic respiration; cytoplasm: glycolysis / matrix: Krebs cycle/oxidative phosphorylation/link reaction; double / inner membranes of mitochondria: chemiosmosis / oxidative phosphorylation; intermembrane space: build-up H+ concentration gradient; inner membrane of mitochondria: electron transfer; inner membrane: ATP synthesis; [6 max] Answers must indicate location and process to receive a mark. Do not award a mark if it is ambiguous whether the candidate is discussing photosynthesis or respiration.