okay in this video we have to cover a concept known as code transport if you notice in this particular diagram I did put the word passive transport which is diffusion osmosis uh active transport bulk transport in no space did I mention anything about core transport at all uh the reason why I did not mention this is because you will only see examples of code transport in chapter 7 plant transport and chapter 14 homeostasis but I do want to cover it a little bit so I just want you to be familiar with what code transport is all about you don't need to memorize it but it helps us um understand chapter 7 and 14 in the future okay and it's good to also realize that such transport proteins exist now Co-op transport is a movement across the cell membrane where it requires a transport protein and it transports usually two substances simultaneously for example you can see the phospholipid bilayer and you can also see the transport protein and in this case the transport protein is a hydrogen ion sucrose core transporter what that means is this protein is able to transport hydrogen ion and sucrose at the same time by the way so I'm going to represent hydrogen ions as red dots and I'm going to represent sucrose as triangles green triangles now notice something quite interesting the concentration of hydrogen ion on one side is higher than the other side and the concentration of sucrose on one side is higher than the other side you can see the difference in the concentration gradient now when you see the word hydrogen ion sucrose co-transporter I want you to focus on the first particle which I've highlighted in this case it is hydrogen ion you must just focus on the concentration gradient of the hydrogen ion in this case now what do I mean by this it means that in Avia a it has a higher hydrogen ion concentration and area B has a lower hydrogen ion concentration what will happen is here one hydrogen ion will diffuse through the core transporter but when it does so it will automatically pull in the sucrose molecule effortlessly so the hydrogen ion that diffuses through will also be accompanied by one sucrose at the same time so as hydrogen ion diffuses down the concentration gradient sucrose will follow now even though sucrose is actually moving from a low concentration of sucrose to high concentration of sucrose it you might be thinking oh that that is active transport no in this case no ATP is expanded at all no ATP is spent by the cell to move the sucrose because the sucrose accompany the hydrogen ion that is what is quite interesting to know about core transport in a nutshell there are also specific examples where um and if you were to do a bit of extra reading on code transport there is something called sympots and also anti-pots you do not need to memorize them for the exam these are all just extra bits of information okay so you do not need to know code transport in detail what I just want you to understand about quote transport is the fact that there are transport proteins that can transport two substances simultaneously but they will just follow the concentration gradient of one of the particle in this case in the hydrogen ion sucrose core transporter it only follows the concentration gradient of hydrogen ions so every time a hydrogen ion diffuses through it down the concentration gradient a sucrose molecule automatically follows and no ATP is spent whatsoever