I Can Explain - The importance of the surface area to volume ratio! - Part ii - By m.w.clark

importance of the surface area to volume ratio the what? I can explain I've got my giant hamster ball back, as a representation of biological cell. remember from the other video, we talked about how one main function of the cell is to keep the outside out from the inside in, that is done actually by the cell in a very regulated fashion. because you need nutrients to get in, so you can build things but waste products are produced, and these waste products need to get out. so all of that has to cross this plasma membrane so it turns out that the actual surface area of the plasma membrane is important that is the part of the cell membrane that is exposed to the outside, but there's another really important factor is that is that the surface area to volume ratio is really important. so this is the giant hamster ball that's about the size of eukaryotic cell, and this is a ping pong ball which is approximately the size of the bacteria. you can see they're quite different in size and volume but i wanna show you how that surface area changes relationship to the volume. now there are number ways to calculate surface area and volume but to me the easiest thing to do is to simply wrap the pingpong ball in a piece of paper and then we can measure the paper, we can do the same thing for the hamster ball, okay? so here's my piece of paper, then wrapping my ping pong ball, you see it's approximate. its not exact. but it's approximate. so when we do that, it turns out that this piece of paper, like that okay, is 19 square inches or 126 square centimeters now let's do the same thing for the hamster ball here's my piece of paper you see it's approximately wrapping the hamster ball when we do that, this sheet of paper ends up being ah, 478 square inches or approximately 3,000 square centimeters quite a large difference compare them specifically visually you can see this is the surface area of the ping pong ball, approximately, and this is the surface area of the hamster ball approximately there's quite a large defference. and actually it takes 23 of these ping pong balls to equal the surface area of the hamster ball so now we've determined the surface area of the hamster ball and the ping pong ball and we've shown that it takes 23 surface areas of a ping-pong balls cover the surface area of the hamster ball. but what about the volume? remember we were talking about surface area to volume ratios? the easiest way to do that is to fill the hamster ball with the ping pong balls. remember I said there were 23 ping pong balls to cover the hamster ball? well, there are 120 ping pong balls inside the hamster ball so the volume difference is substantial. the surface area of those 120 ping pong balls actually makes approximately 2300 square inches or 15,000 square centimeters that's approximately five times the surface area of the hamster ball so you see by being small and occupying the same volume it ends up with more surface area. so it depends on what you want to do but he wanna be a be still for a little cell as to what you want to transport back and forth so it depends on what's going on. but in that hamster ball there are a lot of ping pong balls. do you want to see how many? that's a lot of balls