IB Biology HL Topic 8
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32 terms
Terms | Definitions |
|---|---|
 Oxidation | involves the loss of electrons from an element; frequently involves gaining oxygen or losing hydrogen |
| Reduction | involves a gain of electrons; frequently involves losing oxygen or gaining hydrogen |
| Glycolysis | first stage of cell respiration; in the cytoplasm, one hexose sugar is converted into 2 3-carbon atom compounds (pyruvate) with a net gain of 2 ATP and 2 NADH + H |
| Phosphorylation | 2 phosphate groups are added to a molecule of glucose to form hexose biphosphate; 2 molecules of ATP provide the phosphate groups; the energy level of hexose is raised by phosphorylation |
| Lysis | the hexose biphosphate is split to form 2 molecules of triose phosphate |
| Oxidation | 2 atoms of H are removed from each triose phosphate; the energy released is used to link on another phosphate group, producing a 3-carbon compound carrying 2 phosphate groups; NAD+ is the H carrier that accepts H atoms |
| ATP formation | pyruvate is formed by removing the 2 phosphate groups and by passing them to ADP |
| Aerobic Respiration | the pyruvate produced from glycolysis cannot be oxidised further without the presence of oxygen; occurs in the mitochondria of cells |
| Link reaction | pyruvate from glycolysis is absorbed by the mitochondria; enzymes in the matrix of the mitochondria remove H and CO2 from the pyruvate; the H is accepted by NAD+; oxidative decarboxylation; the product is an acetyl group which is accepted by CoA |
| Krebs Cycle | CO2 is removed in decarboxylations; CO2 is a waste produce and is excreted together with CO2 from the link reaction; H is removed (oxidations), and in 3, H is accepted by NAD+, 1 H is accepted by FAD; oxidations release energy which is stored by carriers and later released by ETC to produce ATP; ATP produced during substrate-evel phosphorylation |
| Electron Transport Chain | a series of electron carriers; located in inner membrane of mitochondria; NADH supplies 2 electrons to the first carrier in chain (electrons come from oxidation reactions in earlier stages of cell respiration); the 2 electrons pass along the chain of carriers because they give up energy each time they pass from one carrier to the next; at 3 points along the chain, enough energy is given up for ATP to be made by ATP synthase; FADH2 also feeds electrons into chain |
| Oxygen | accepts H ions to form water; if it is not available, electron flow along the ETC stops and NADH+H cannot be reconverted into NAD+; increases ATP yield |
| Chemiosmosis | the coupling of ATP synthesis to electron transport via a concentration gradient of protons |
| Matrix | structure of mitochondria; fluid inside containing enzymes for Kreb's cycle and link reaction |
| Outer mitochondrial membrane | structure of mitochondria; separates the contents inside from the rest of the cell; creates ideal conditions for aerobic respiration |
| Inner mitochondrial membrane | structure of mitochondria; contains ETCs and ATP synthase (oxidative phosphorylation) |
| Cristae | structure of mitochondria; tubular projections of inner membrane which increase the SA available for oxidative phosphorylation |
| Space between outer and inner membranes | structure of mitochondria; protons pumped into space by ETC; because it is small, a high proton concentration can easily be formed in chemiosmosis |
| Photosynthesis | the process that plants, algae, and some bacteria use to produce all the organic compounds that they need |
| Light dependent reactions | need a continual supply of light |
| light independent reactions | need light indirectly, but can carry on for some time in darkness |
| Light dependent reactions | produce intermediate compounds that are used in the light-independent reactions; photoactivation of photosystem II; photolysis of water; electron transport, cyclic and non-ccylic photophosphorylation; photoactivation of photosystem I; reduction of NADP+ |
| Photophosphorylation | the production of ATP using the energy of sunlight; made possible as a result of chemiosmosis (the movement of ions across a selectively permeable membrane, down their concentration gradient); during photosynthesis, light is absorbed by chlorophyll molecules; electrons within these molecules are then raised to a higher energy state and then travel through Photosystem II, a chain of electron carriers and Photosystem I; as electrons travel through chain of electron carriers, release energy that is used to pump hydrogen ions across the thylakoid membrane and into the space within the thylakoid; concentration gradient of H ions forms w/n this space and move back across the thylakoid membrane, down their concentration gradient through ATP synthase which uses energy released from the movement of H ions down their concentration gradient to synthesise ATP from ADP and inorganic phosphate |
| Light independent reactions | occur in the stroma of the chloroplast and involve the conversion of carbon dioxide and other compounds into glucose; can be split into three stages: carbon fixation, the reduction reactions and regeneration of ribulose bisphosphate |
| Large surface area of thylakoids | allows for increased light absorption |
| small space inside thylakoids | allows for accumulation of protons inside the chloroplast |
| fluid stroma | hold enzymes of the Calvin Cycle |
| Action spectrum | a graph showing the rate of photosynthesis for each wavelength of light; the rate of photosynthesis will not be the same for every wavelength of light; the rate of photosynthesis is the least with green-yellow light (525 nm-625 nm); red-orange light (625nm-700nm) shows a good rate of photosynthesis however the best rate of photosynthesis is seen with violet-blue light (400nm-525nm) |
| Absorption spectrum | a graph showing the percentage of light absorbed by pigments within the chloroplast, for each wavelength of light |
| Light intensity | at low levels, there is a shortage of products of the light dependent reactions |
| CO2 concentration | at low and medium levels, the rate-limiting step in the Calvin cycle is the point where CO2 is fixed to produce glycerate 3-phosphate |
| Temperature | at low levels, all enzymes work slowly; at high levels, RuBP carboxylase does not work effectively |
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