What 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.
Practice
- Check yourself: What are enzymes? – 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
Your body does thousands of chemical reactions every second. We call them metabolic reactions. For example, digesting food, releasing energy, and building new proteins.
But at body temperature, most of these reactions would be much too slow. Without help, we could not stay alive.
A catalyst is a substance that speeds up a chemical reaction. With a catalyst, the same reaction happens much faster.
A catalyst is not used up in the reaction. So the same catalyst can work again and again.
In living things, the catalysts are enzymes. Enzymes are proteins. We say that enzymes are biological catalysts.
Here is an example. Amylase is an enzyme in your saliva. It breaks starch into smaller sugars called maltose.
Remember. An enzyme is a protein. It is a biological catalyst. It speeds up reactions. And it 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.
1:40How 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.
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.