So the element carbon is actually an excellent building block, and 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. 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 below right here. Those variations 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. Let's take a look at our example image below to see the variations of carbon backbones.
Over here in the first image, we're showing how, point number 1, which of course corresponds with number 1 above, illustrates that the length of carbon backbones can change. 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. You'll see different molecules throughout that have different lengths of the carbon backbone. That's the first characteristic of the carbon backbones. The second characteristic concerns the positions of double bonds within the carbon backbone.
Notice that this molecule over here has a double bond between the first two carbons in the carbon backbone, whereas this molecule over here has a double bond between the second and the third carbon atoms in the carbon backbone. Therefore, the position of the double bond can vary. The third characteristic of carbon backbones are the branch points. 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 branching off of it. Here we have a branched carbon backbone. The fourth and final characteristic here are the ring forms.
We've seen examples of the carbon backbone being in a linear form like all of these, but the ones below show that the carbon backbone can also be in a ring form, as we see here and here. Notice that the ring form can also have double bonds within it as well. This goes to show how many of the molecules that we're going to talk about moving forward are built using carbon as the backbone. 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 from this video.
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. I'll see you all in our next video.