* KS4 Science GCSE/IGCSE Industrial Chemistry Revise 2 Enzymes and Biotechnology at Doc B's
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Doc Brown's Chemistry
Industrial Chemistry 2. Enzymes and Biotechnology Revision KS4 Science GCSE/IGCSE/O level Chemistry Information Study Notes for revising for AQA GCSE Science, Edexcel 360Science/IGCSE Chemistry & OCR 21stC Science, OCR Gateway Science (revise courses equal to US grades 9-10) Index of sections: 1. Limestone, lime - uses, thermal decomposition of carbonates, hydroxides and nitrates * 2. Enzymes and Biotechnology * 3. Contact Process, the importance of sulphuric acid * 4. How can metals be made more useful? (alloys of Al, Fe, steel etc.) * 5. The importance of titanium * 6. Instrumental Methods of Chemical Analysis * 7. Chemical economics of processes and sociological and environmental issues etc. and other web pages of industrial chemistry: Ammonia synthesis/uses/fertilisers * Oil Products * Extra Organic Chemistry * Extraction of Metals * Halogens - sodium chloride Electrolysis * Transition Metals * Extra Electrochemistry * EMAIL comment?query * |
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2.
Enzymes and Biotechnology
(see
also rates
notes at end of 2.) Aspects of the vitamin, food and drugs GCSE chemistry are on the "Extra Organic Chemistry" page. Living cells use chemical reactions to produce new materials. Living things produce catalysts called enzymes which allow chemical reactions to occur quite quickly at ordinary temperatures and pressures. Enzymes are powerful 'biochemical catalysts' and are widely used in the food industry and are being used more and more to manufacture many other chemicals. These biological catalysts promote most of the reactions in living tissue. The names of enzymes end in ...ase e.g. amylase, protease, invertase, isomerase etc.
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Rates of Reaction - kinetics of Enzymes
(full
rates of reaction notes)
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Concentration: If either the substrate reactant e.g. sugar, or the yeast cell (enzyme) concentration is increased, the rate of reaction increases in a simple proportional way. However, if the concentration of enzyme is low but the substrate concentration is very high, the rate of reaction rises to a maximum and then stays constant. This is because the maximum number of catalyst sites for the 'key and lock' mechanism are in use and the rate of reaction depends on the rate of diffusion of substrate in and product out. |
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pH effect: The structure of the protein enzyme
can depends on how acid or alkaline the reaction medium is, that is, it is
pH dependent. If it is too acid or too alkaline, the structure of the protein
is changed and it is 'denatured'. If the enzyme does not have the correct 'lock' structure, it
cannot function efficiently by accepting the 'key' substrate molecule. Most enzymes have an optimum pH of between 4
and 9, and quite frequently near the neutral point of 7. However, the
enzyme pepsin has a peak at pH2 and can operate in the very acid
(hydrochloric) conditions of the stomach to help breakdown proteins for
digestion in the small intestine. |
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Temperature: The structure of the protein enzyme can depend the temperature. If the enzyme does not have the correct 'lock' structure, it cannot function efficiently. The shape of the graph is due to two factors. (1) The initial rise in rate of reaction is what you normally expect for any chemical reaction. The increase in temperature increases the average kinetic energy (KE) of the molecules to increase the chance of the product forming from the higher KE 'fruitful collisions. (2) However as the temperature rises further, the increasing thermal vibration of the enzyme molecule causes its structure to break down (denature) and so the 'lock' is damaged so the enzyme is less efficient (see key-lock below). This may be due to the failure of weak intermolecular forces or actual ionic/covalent bonds, but the 3D molecular structure of the enzyme is changed so that the substrate molecule cannot 'dock in' to be changed into products. The optimum temperature for the fastest rate of reaction is often around 30-40oC (note our body temperature is about 37oC, no coincidence!). Eventually at high temperatures the enzyme ceases to function. |
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Explaining
enzyme biochemical catalysis
Extra Advanced chemistry notes on Enzyme structure on the stereochemistry page
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| (portuguese) Doc Brown de Química Industrial 2. Enzimas e Biotecnologia As células usam reações químicas para a produção de novos materiais. seres vivos produzem catalisadores chamadas enzimas que permitem que as reações químicas que ocorrem muito rapidamente em temperaturas e pressões ordinárias. Enzimas são "poderosos catalisadores bioquímicos e são amplamente utilizados na indústria de alimentos e estão sendo usadas mais e muito mais para fabricar muitos outros produtos químicos. Estes catalisadores biológicos promovem a maioria das reações em tecidos vivos. Os nomes das enzimas no final ... ase por exemplo, amilase, protease, invertase, etc isomerase Taxas de Reação - cinética de enzimas Explicando enzima catálise bioquímica * |
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