Enzymes
Enzymes are protein catalysts that speed up reactions.
About this topic
Enzymes are biological catalysts, mostly proteins, that speed up reactions by lowering activation energy and are not used up. Each has an active site with a specific shape that binds its substrate, as in the lock-and-key model (or induced fit). Enzymes are specific to one reaction.
Digestion, respiration and DNA copying all rely on enzymes. Their names often end in -ase, such as amylase, protease and lipase. Without them, life's reactions would be too slow.
Amylase in your saliva is a good example: chew a cracker for a minute and it starts to taste sweet as amylase breaks starch into sugars. Each enzyme fits only one substrate, so amylase cannot digest protein. After the reaction the enzyme is released unchanged and can work again, so tiny amounts do a lot of work.
Enzymes are used in washing powders to remove stains, in making lactose-free milk, and in converting starch into syrup. Lactose intolerance happens when people stop making enough lactase. A common misconception is that enzymes are alive or are used up; they are just molecules. Also, enzyme names usually end in ase, a handy clue in exams.
Key ideas
- Active site fits the substrate
- Lock and key or induced fit
- Specific to one reaction
Quick check
Use cases: where Enzymes helps
- Homework: review the key idea behind Enzymes before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Enzymes without notes.
- Visual learning: play with the interactive lab to see how Enzymes changes when you adjust its inputs.
- Teaching a friend: explain Enzymes in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is Enzymes?
Enzymes are protein catalysts that speed up reactions.
What will I learn in Enzymes?
Active site fits the substrate. Lock and key or induced fit. Specific to one reaction.
Is Enzymes part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Enzymes lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Enzymes?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.