Enzymes Flashcards
Why do living things produce enzymes that as as biological enzymes ?
living things have thousands of different chemical reactions going on inside them all the time. These reactions need to be carefully controlled - to get the right amount of substances.
You can usually make a reaction happen more quickly by raising the temperature. This would speed up the useful reactions but also the unwanted ones too. There’s also a limit to how far you can raise the temperature inside a living creature before its cells start getting damaged.
What is a Catalyst ?
A substance which speeds up the rate of a reaction without being changed or used up in the reaction.
What are enzymes (biological catalyst )?
large proteins and all proteins are made up of chains of amino acids. These chains are folded into unique shapes, which enzymes need to do their jobs.
Purpose of an enzymes active site
Chemical reactions usually involve things either being split apart or joined together.
Every enzyme has an active site with a unique shape that fits onto the substance involved in a reaction.
Why do enzymes only catalyse one specific reaction ?
for enzymes to work, the substrate has to fit into its active site. If the substrate doesn’t match the enzymes active site, then the reaction won’t be catalysed
Lock and key theory model of enzyme action
Induced fit model of enzyme action
its simpler than how enzymes actually work.
In reality, the active site changes shape a little as the substrate binds to it to get a tighter fit.
What affects enzymes ?
1) changing the temp changes the rate of an enzyme-catalysed reaction
1) like any other reaction, a higher temp increases the rate at first but if its too hot, some of the bonds holding the enzymes together break. This changes the shape of the enzyme’s active site, so the substrate won’t fit anymore . The enzyme is said to be denatured
What also affects enzymes ?
1) The pH, If its too high or low, the pH interferes with the bonds holding the enzymes together. This changes the shape of the active site and denatures the enzymes.
2) All enzymes have an optimum pH that they work best at. Its often neutral pH 7 but not always. e.g. pepsin is an enzyme used to break down proteins in the stomach. It works best at pH 2 which means its well suited to the acidic conditions.
