Lock and Key theory GCSE Biology

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Madz178
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does anyone know any info about this theory that I can put on my poster like some limitations or comparing this to the induced fit model or how this is this applied or can be used by scientists today thanks x
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astrostardromada
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I do edexcel, and we were taught that the lock and key theory is based on enzymes. That basically, an enzyme has an active site (a gap in its shape), that only fits into a certain substrate and when they bind together it causes the enzyme to work. so, substrates fit into an enzyme the way a key fits into a lock. And that there are factors that cause the shape of the active site to change and no longer allow the substrate to bind to the enzyme. Enzymes that have changed shape and no longer allow the subtrate into its active site is said to have denatured. The factors include the pH level, concentration and temperature.

As the concentration of the substrate increases, so does the rate of enzyme activity. However, the rate of enzyme activity does not increase forever. This is because a point will be reached when the enzymes become saturated and no more substrates can fit at any one time even though there is plenty of substrate available. pH increases so does the rate of enzyme activity. An optimum activity is reached at the enzyme’s optimum pH. A continued increase in pH results in a sharp decrease in activity as the enzyme’s active site changes shape. It is now denatured.As the temperature increases so does the rate of enzyme activity. An optimum activity is reached at the enzyme's optimum temperature. A continued increase in temperature results in a sharp decrease in activity as the enzyme's active site changes shape meaning it has denatured.


i have no idea what the induced fit model is but I highly doubt they'll ask you limitations on models in a bio paper as they only ever spend page on enzymes and if it wasnt on the 2018 or 2019 paper and was done fairly recently before the 9-1 system i highly doubt it'll come in the test. But you should revise it anyway but dont worry about it, but then again i dont know what exam board you're doing. so anyways good luck and soz for the long reply!
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