in this video we're going to explore the world of enzymes so we'll take a look at what enzymes do and how they work and then at the differences between the two main models of enzyme action namely the lock and key model and the induced fit model before we get to enzymes themselves though we first of all need to understand why enzymes are so important to us the key reason is that in order for a living cell to function properly it has to carry out a huge number of chemical reactions every second of every day but
the problem is that most of these chemical reactions are naturally quite slow the most obvious way to increase the rate of a reaction would be to increase the temperature but this runs into a few problems and makes it unfeasible for example it can require a huge amount of energy to keep an entire organism very warm and those high temperatures can also damage ourselves most importantly though high temperatures would also speed up non-useful reactions that we don't want to happen so because of all these problems a better way to increase the speed of camel corrections is
with a catalyst we can define a catalyst as a substance that increases the speed of a chemical reaction without being changed or used up in the process and this last bit of the definition is really important because it means that catalysts can be used over and over again to catalyze multiple reactions without being used up now the word catalyst is a general term that you might see in chemistry as well but an enzyme is a particular type of catalyst that's made by living organisms and so we sometimes call them biological catalysts enzymes themselves are basically
just large proteins so like all proteins they're made up of long chains of amino acids and depending on the specific sequence of amino acids in the chain they can fold up to form different shapes and each of these shapes would be a unique enzyme that catalyzes a particular chemical reaction so now that we know what enzymes are we need to look at how they work if you think about chemical reactions they often involve taking a reactant which in biology we can call a substrate and breaking it apart into smaller pieces which we can call products
and the reverse is also very common with chemical reactions joining together multiple substrates into a single product the important thing to remember is that all enzymes do in these cases is speed up of the process and to do this they have a special region called an active site which is a part of the enzyme with a unique shape that's complementary to the substrates of the reaction and this point is really important if the substrate doesn't fit the active site of the enzyme then the reaction won't be catalyzed and this allows the enzymes to be really
specific about which reactions they speed up the very last thing we discover are the two models of enzyme action so the original lock and key model and the more realistic induced fits model at first scientists thought that these substrates had to fit perfectly into the active site just like how a key fits perfectly into a lock hence the name lock and key model however we now know that the enzyme actually changes shape slightly as it binds to the substrate so they can fit together more perfectly in exams you want to describe this by saying that
the active site is complementary to the substrates if you want you can think of the induced fit model kind of like putting your hand into a rubber glove the rubber glove wasn't a perfect fit for your hand to start with but when you put your hand in it molds around your hand and becomes a perfect fit hey everyone amadeus here i just wanted to let you know that we also have a learning platform where you can watch all of our videos practice what you've learned with questions and keep track of all of your progress for
the sciences and maths it's completely free so if you haven't already you can check it out by clicking on our logo here on the right or if you'd like to do the lesson for this particular video we put the link to that in the description down below we've also arranged all the videos for this subject in a playlist for you here that's all though so hope you enjoy and i'll see you next time thanks
