How enzymes work
The active site, the substrate, the enzyme-substrate complex and the products; why complementary shapes make an enzyme specific. With Vietnamese subtitles. A “Check yourself” section with typed questions is below the video on the site.
Practice
- Check yourself: How enzymes work – Type the missing words, put the steps in order and write a short answer. No multiple choice: you have to remember it. Vietnamese help for every question.
Transcript
Every enzyme has a special place called the active site. The molecule that the enzyme works on is called the substrate.
The substrate fits into the active site. Together, they make the enzyme substrate complex.
Then the reaction happens. The substrate changes into products, and the products leave. The enzyme is free to work again.
The shape of the active site is complementary to the shape of the substrate. They fit together exactly, like a key in a lock.
Other molecules have a different shape. They do not fit. So each enzyme is specific. It works with only one kind of substrate.
Remember, the enzyme is not used up. It can take another substrate straight away. So one enzyme can change many substrates.
Remember. The substrate fits the active site. The enzyme substrate complex makes products. Complementary shapes make an enzyme specific. And the enzyme is not used up.
More in this series
5:53B4 Enzymes: key vocabulary
Twelve key words for IGCSE Co-ordinated Sciences topic B4, with the Vietnamese meaning, how to say each word, a picture and an example. Ends with a test section, and a typing trainer on the site.
1:41What are enzymes?
Why the body needs catalysts, what a catalyst does, and why enzymes are proteins that work as biological catalysts. With Vietnamese subtitles. A “Check yourself” section with typed questions is below the video on the site.
2:14Enzymes: temperature and pH
Why a higher temperature speeds up an enzyme, what the optimum is, and how heat or the wrong pH changes the shape of the active site (denaturation). With Vietnamese subtitles. A “Check yourself” section with typed questions is below the video on the site.
2:16Investigating enzymes: temperature and pH
A practical with amylase, starch and iodine on a spotting tile: how to test the effect of temperature and pH, keep it a fair test and read the results. With Vietnamese subtitles. A “Check yourself” section with typed questions is below the video on the site.
5:30B4 quiz: enzymes
Ten think-time questions on enzymes: catalysts, the active site, specificity, temperature, pH and the amylase practical. Below the video: written workbook questions with model answers.