hello welcome today we're looking at this idea of fermentation in yeast and fermentation is another way of talking about anaerobic respiration in yeast so if you've watched the video previous to this you may remember that when we have anaerobic respiration in yeast we have this summary equation we've got glucose that is then in a reaction that produces ethanol and carbon dioxide so this is respiration without oxygen and just to remind ourselves yeast is a microorganism so i can just enlarge that to so we can see yeast is a microorganism that carries out anaerobic respiration it can do aerobic respiration as well but here we've made it so it can only do anaerobic by stopping any oxygen from getting in so there's our yeast happily respiring away in our container which is a conical flask and this is producing two products those two products are ethanol and carbon dioxide the carbon dioxide will leave through this tube whereas the ethanol will be produced and stay inside the container now ethanol is alcohol so this process this process of fermentation can be used to produce alcohol so should we say actually more accurately produce alcoholic drinks uh things like beer that can be produced in this way so this process can produce alcoholic drinks because of the alcohol that's produced the the alkanal or the ethanol here can also be used as a fuel the type of fuel that we talk about is biofuel so this ethanol that's produced can also be burnt to produce a fuel so this is one use of anaerobic respiration in yeast or in other words one use of fermentation another use is based on the idea that carbon dioxide is produced and remember carbon dioxide is a gas so we use this idea in baking bread so imagine we've got some dough so if i was just to draw supposed to be some dough which makes bread if we have some yeast inside there it can carry out fermentation or anaerobic respiration produce carbon dioxide gas and that will produce little bubbles inside the dough after a while keep it in warm conditions after a while the dough will rise and this gives bread a slightly better texture makes it nicer and lighter to eat so this is our dough we would then bake that in the oven remember ethanol is produced in this process as well this is alcohol so we don't want alcohol in our bread but luckily when we bake this in the oven all the ethanol evaporates away and is gone so we end up with a nice loaf of bread it might look a bit like this not quite sure that's the color of bread but you understand this is bread that's been baked from this dough that has yeast in it so this is just really an outline of two potential uses of this idea of fermentation in yeast one is to produce alcoholic drinks or even produce biofuel because of the ethanol and the other is to use the carbon dioxide which helps dough to rise when we bake bread okay so that's it thanks very much and i'll see you soon