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Lock and Key Model

Key Stage 3

Meaning

The lock and key model is a model used to explain why enzymes only work on certain substrates.

About The Lock and Key Model

The lock and key model proposes that an enzyme is a like lock and a substrate is like a key as only one key can fit a lock, just as only one substrate can fit an enzyme.
DenaturedEnzyme.png
This diagram shows an enzyme (the lock) and the substrate (the key) fitting together. If the lock is 'denatured' the key no longer fits the lock and so the enzyme does not work.

Key Stage 4

Meaning

The lock and key model is a model used to explain why enzymes only work on certain substrates.

About The Lock and Key Model

The lock and key model proposes that an enzyme is a like lock and a substrate is like a key as only one key can fit a lock, just as only one substrate can fit into the active site of an enzyme.
DenaturedEnzyme.png
This diagram shows an enzyme (the lock) and the substrate (the key) fitting together. If the lock is 'denatured' the key no longer fits the lock and so the enzyme does not work.

References

Edexcel

Lock and key model, page 37, GCSE Biology, CGP, Edexcel
Lock-and-key model of enzymes, page 15, GCSE Combined Science, Pearson Edexcel
Lock-and-key model of enzymes, page 19, GCSE Biology, Pearson, Edexcel