This is a legacy topic. View the most up to date content by selecting the exam board in the dropdown to the left.
Enzymes are proteins which catalyse (speed up) metabolic reactions. Like all other catalysts (e.g. in chemistry), enzymes achieve this by lowering the activation energy (energy needed for a reaction to occur) of a reaction, by forming an enzyme-substrate complex.
This can be described by the lock and key, and induced fit models of enzyme action. The lock and key model is based on complementary shapes between the enzyme and substrate. The substrate fits into the enzyme.
The induced fit model: (the enzyme changes shape to “hug” the substrate)
The enzyme’s shape is not exactly matched to the substrate, but it is able to accommodate the substrate with a close enough shape into an enzyme-substrate complex and carry out catalysing that reaction. Here is a video of an enzyme catalysing a reaction between two molecules into one molecule. This is different to the above scenario in the diagrams, where one molecule is broken down into two molecules.
OFF TOPIC : I just want to say that your website is brilliant, thank you!!
You're such a G. Helped me so much, finally found someone who breaks biology down into something I can understand!!!
Alex Contact Form
wow just checked out your website and think it’s pretty cool.
Eager bug The Student Room
Hi! I have recently finished my first year doing biology at uni and I subscribed to you back when I was doing AQA A levels (glad I don’t live in Wales after watching this vid lol) and you and your website helped me so much. Just wanted to say it’s so nice to see you
Mr Peanutbutter YouTube
I bookmarked the site
translucent The Student Room