So the element carbon is actually an excellent building block and so in this video we're going to focus on that idea. Now carbon's ability to form a total of 4 covalent bonds really is what makes it such a flexible atomic building block for building a variety of different types of molecules. And so the carbon backbones of organic molecules such as carbohydrates, proteins, nucleic acids, or lipids can actually vary in 4 different ways that we have listed down below right here. And those are in the length of the carbon backbone, the position of double bonds within the carbon backbone, the branch points of the carbon backbone, and the carbon backbone being in either a linear form or a ring form.

And so if we take a look at our example image down below, we can see the variations of carbon backbones. And so over here in the first image, what we're showing you is how, number 1, which of course corresponds with number 1 up above, is that the length of carbon backbones, are capable of changing. And so notice that this first molecule over here has 2 carbons in its carbon backbone, whereas this molecule over here has 3 carbon atoms in its backbone. And so you'll see different molecules throughout that have different lengths of the carbon backbone.

Now the second one are the positions of double bonds within the carbon backbone. Notice that this molecule over here has a double bond between the first 2 carbons in the carbon backbone, whereas this molecule over here has a double bond between the 2nd and the 3rd carbon atoms in the carbon backbone, and so the position of the double bond can vary.

Now the third characteristic here of carbon backbones are the branch points. And so, of course, you can have a linear carbon backbone that does not have any branch points, but notice this molecule over here actually has a carbon backbone and another backbone that is branching off of it, and so here we have a branched carbon backbone.

Now the 4th and final characteristic here are the ring forms. And so, of course, we've seen examples of the carbon backbone being in a linear form like all of these, but the ones that you see down below show that the carbon backbone can be in a ring form as we see over here and over here, and notice that the ring form can also have double bonds within it as well. And so this here just goes to show how a lot of the molecules that we're going to talk about moving forward, they're going to be built using carbon as the backbone. And carbon is a really useful atomic building block, because it can be built in so many different fashions as we see right here, and that's really the main takeaway here of this video.

And so that concludes our lesson on how carbon is such an excellent building block and we'll be able to see these concepts applied as we move forward throughout our course. So I'll see you all in our next video.