so let's classify all the ways that something can get through the cell membrane and we're gonna start out by looking at we're gonna classify these things based on how much energy is required so remember we're looking at getting stuff in and out through the cell membrane how are we going to pull it off there are two techniques one of them is passive and it's considered passive transport and the other active it's considered active transport and the difference between passive transport and active transport is 100% the amount of energy that's required to make this happen passive transport this is my energy signal passive transport requires no energy I say it requires no energy it actually utilizes the energy that's already found in all the molecules in the entire universe except for molecules that are at Absolute Zero the temperature absolute zero which is like negative 312 degrees Celsius like it's ridiculous or maybe it's negative 293 degrees Celsius it's something two hundred and ninety four point seven three degrees cells it's crazy it's cold and we've never been there to absolute zero we've tried and we've gotten pretty close but we think that it absolute zero all matter will stop moving like all atoms will stop moving and then they'll like collapse into each other and turn into a crazy protoplasm of neutrons or something like that which that sounds terrible let's not do that so assuming you do not go to absolute zero passive transport realize just on the random kinetic energy that all molecules already have think about kinetic energy of molecules this is drawing you back to your chemistry rockstar days you know that the more kinetic energy a molecule has the more - moving around the higher the temperature of that substance so temperature is actually a measure of the kinetic energy of the molecules so they're all moving around passive transport just moves molecules based on that kinetic energy active transport actually requires an input of energy and I'm just gonna throw this out here I'm gonna do a little like signal often that energy in the cell comes in the form of ATP or adenosine triphosphate and you know all about adenosine triphosphate also from your general bio days so passive transport we really don't have to throw in any extra energy so so how does it happen passive transport happens through all of them happen all of my examples of passive transport happen through the process of diffusion and we have a couple of different flavors so diffusion let's define it oh I think I had a picture for you diffusion is the movement of molecules from an area of high concentration to an area of low concentration and I really do feel that was like the most amazing thing no I don't think that's my diffusion picture yeah it is my diffusion picture so ignore the semipermeable membrane in the middle diffusion is the movement of molecules from a high concentration to a low concentration the semipermeable membrane in the middle is optional diffusion can happen through a semipermeable membrane but in order to think about diffusion I just said we are talking about a high concentration to a low concentration and let's take a second to define concentration concentration is nothing more than the number of particles in a solution given a certain volume of the solution the particles are called solutes and I call them particles because we're going to use there's a couple of concentration units of concentration that are significant to us one of them is molarity molarity is one way to measure a concentration of a solution and the molarity measures moles of solute per liters of solution so you can imagine okay take a number how many moles of red dots do we have over here 10 right because here we have only one mole of red dots do you totally agree with that but the volume what's my volume over here one liter what's my volume over here one liter so we have 10 moles per liter on the left side and we have one mole per liter on the right side I totally just made up my numbers numbers are irrelevant I'm giving you an example to show you how we calculate molarity which means on the right side we have a one molar solution and on the left side we have a 10 molar solution does that work you now can tell me which side is more concentrated dude you don't even have to add numbers into the scene it's very clear that this is the more concentrated side so where are those red particles going to go they're gonna move down their concentration gradient that's just saying they're going to move from an area of high concentration to an area of low concentration high concentration low concentration we have a gradient between those and molecules move down that gradient if they're moving down the gradient I think of it as little balls or marbles rolling down a hill do you have to put any energy in like maybe you just flick them a little bit to get them to go but if they were like bouncing around already they totally would roll down the hill without any help from you oh my god we went backpacking today and my small child his sleeping bag fell out of his backpack and tumbled down the concentration gradient it was kind of a small miracle that it stopped on a tree I was like dude I'm out because I'm not climbing down that concentration gradient to go get that sleeping bag but my rock star partner was like I got those and tromped through the forest down the concentration gradient doesn't take as much energy to go down the concentration gradient to get the seat belt I mean the sleeping bag but then he had to turn around and come back up you can imagine is that going to take more energy absolutely okay where were we concentrations we calculated concentrations we have an idea of concentration gradient if things are moving down their concentration gradient that is an example of diffusion we have a couple of flavors of diffusion you guys we can have simple diffusion simple diffusion happens when molecules move directly through the cell membrane oxygen carbon dioxide those are the two best examples of substances that move directly through the cell membrane it's fast it's easy you don't need any help you also have still diffusion you can have diffusion through a channel and we're going to talk about channels in a little bit more detail in the next one and you can also have diffusion through a carrier and a carrier is just going to say hey you're still moving down your concentration gradient because it's diffusion but a carrier is going to do that like pac-man work to help you get through the cell membrane both of these are examples of facilitated diffusion they're requiring a protein helper to get through the cell membrane simple diffusion dude we can go through the cell membrane nobody's nobody's holding my hand nobody's helping me facilitated diffusion I need some help I can't get through unless I have my own special tunnel to go through or I have a little Pacman guy who's gonna actually let me through and we'll talk about channels and carriers we're going to talk about both of those in the next section now active transport active transport maybe I should write this down diffusion goes down the concentration gradient active transport goes against the concentration gradient which is why it requires energy so we have to put energy in it always requires a carrier and we can have primary active transport or oops secondary active transport and I have an entire section on active transport because the difference between primary and secondary active transport gets kind of crazy active transport also includes something called vesicular vesicular transport and that is endocytosis or exocytosis those processes and we'll talk about those as well they both also require energy they're not carrier based these guys right here I'm going to circle all my friends that require carriers those guys um require proteins of some sort to get through because a channel isn't considered a carrier carriers are only open to the extracellular fluid or the intracellular fluid one at a time alright so I think the next thing we're talking about is channels oh I'm so excited Cal be right back to talk about channels