What is an enzyme? Explain the 'Lock and Key' Hypothesis

An enzyme is a biological catalyst. This means that (like all catalysts) it increases the rate of the reactions it takes part in without being used up. Each enzmye has an active site which is specifc for a certain substrate (reactant particle). The idea of the substrate fitting 'just right' to the active site of the right enzyme is called the 'Lock and Key' hypothesis.If the active site is altered by exptremes of teperature or changes in pH then the substrate won't fit into it as well and will lead to a decrease in the activity of the enzyme. 

Hope this was helpful! :)

Wisdom O. GCSE Biology tutor, IB Biology tutor, GCSE Chemistry tutor,...

10 months ago

Answered by Wisdom, a GCSE Biology tutor with MyTutor

Still stuck? Get one-to-one help from a personally interviewed subject specialist


£18 /hr

Valentina G.

Degree: Biology (Masters) - York University

Subjects offered:Biology, Italian


“Studying Biology is extremely interesting but also challenging, that is why I want to help to allow students to look past challenging and focus on interesting!”

Trusted by schools

|  2 completed tutorials

£20 /hr

Samuel A.

Degree: Medicine (Bachelors) - University College London University

Subjects offered:Biology, Maths+ 2 more

-Medical School Preparation-

“Hello I'm Samuel Aston and I'm a second year UCL medic looking for students needing help in attaining their full potential and the top marks!”

£24 /hr

Xanthe W.

Degree: Biological Sciences with a Year in Industry/Research (Bachelors) - Imperial College London University

Subjects offered:Biology, Maths+ 1 more


“Top tutor from the renowned Russell university group, ready to help you improve your grades.”

About the author

Wisdom O.

Currently unavailable: for new students

Degree: Medicine, MBBS iBsc (Bachelors) - University College London University

Subjects offered:Biology, Maths+ 5 more

-Personal Statements-
-Oxbridge Preparation-
-Medical School Preparation-

“ABOUT ME   I'm a first year medical student at University College London. I really enjoy sciences and languages and I work hard to convey my passion and interest in these subjects to those I tutor.  I am very friendly and tutoring my ...”

You may also like...

Posts by Wisdom

What is an enzyme? Explain the 'Lock and Key' Hypothesis

What's the difference between 'sollen' and 'sollten'?

Other GCSE Biology questions

Why is diffusion important in plants and animals? Give examples

Of what is the Central Nervous System comprised?

What is the correct order of the reflex arc?

What is the difference between breathing and respiration?

View GCSE Biology tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss