Inner Life of a Cell | Protein Packing (NT TImes)

Two years ago, BioVisions and Xvivo set out to upgrade their animations by capturing some of the messy complexity of protein movements. They wanted to cram a virtual cell with proteins at a more realistic density, and then have them jitter and collide

In this movie, we enter a neuron by diving through a channel on its surface. Once inside, we’re instantly surrounded by a swarm of molecules. We push through the crowd until we reach a proteasome, a barrel-shaped molecule that shreds damaged proteins so their components can be used to make new proteins.

Once more we see a vesicle being hauled by kinesin. But in this version, the kinesin doesn’t look like a molecule out for a stroll. Its movements are barely constrained randomness.

Every now and then, a tiny molecule loaded with fuel binds to one of the kinesin “feet.” It delivers a jolt of energy, causing that foot to leap off the molecular cable and flail wildly, pulling hard on the foot that’s still anchored. Eventually, the gyrating foot stumbles into contact again with the cable, locking on once more — and advancing the vesicle a tiny step forward.

This updated movie offers a better way to picture our most intricate inner workings. For one thing, it helps us to understand why we become sick. A number of diseases, such as Alzheimer’s and Parkinson’s, are caused when defective proteins clamp onto other proteins, creating toxic clumps.

OK, so yesterday I promised a special treat for those of you who love the now-famous Inner Life of the Cell video.  Here it is!  The Harvard University team behind that video has created a new animation highlighting the powerhouse of the cell, the mitochondria.  If you thought the last one was complicated, it’s got nothing on this one.

The little prokaryotic endosymbionts that we call the mitochondria are a biological world unto themselves, participating in unique biochemistry that takes place nowhere else in the cell.  You’ll see redox, ATP synthesis, ion gradients … enjoy.