I usually use a combination of several software. If I found a royalty free image similar to something that I try exemplify, I just make some adjustments with Gimp. Otherwise, I start from zero and use blender and PyMol to render proteins (ribbons or atoms) and then i make the necessary adjustments using Krita. Blender is an open access professional 3D rendering software and have some scripts to load PDB files, so you can make biological animations with blender. Also, there is a blender distribution that focus on biological animations named Bioblender. And Molecular Flipbook is another 3D rendering software for biological animation, easier to use than blender. I hope it helps, and good look with your project.
I usually use a combination of several software. If I found a royalty free image similar to something that I try exemplify, I just make some adjustments with Gimp. Otherwise, I start from zero and use blender and PyMol to render proteins (ribbons or atoms) and then i make the necessary adjustments using Krita. Blender is an open access professional 3D rendering software and have some scripts to load PDB files, so you can make biological animations with blender. Also, there is a blender distribution that focus on biological animations named Bioblender. And Molecular Flipbook is another 3D rendering software for biological animation, easier to use than blender. I hope it helps, and good look with your project.