Gap Junctions

by Greg Crowther

Although the cell is the basic unit of structure and function for multicellular organisms, individual cells are not completely isolated from each other. For example, protein channels called gap junctions connect adjacent cells, such that ions and small molecules can pass directly from one cell to another.

How do muscle cells talk if they're smooth or cardiac?
Cross the gap, cross the gap, cross the gap!
How do neurons connect at an electrical synapse?
Cross the gap, cross the gap, cross the gap!

Gap junctions are in membranes at locations such as axons.
Proteins called connexins make up channels called connexons.

Cells that do not excite likewise must interact.
Cross the gap, cross the gap, cross the gap!
There are nutrients shared when they diffuse forth and back.
Cross the gap, cross the gap, cross the gap!
Cross the gap, cross the gap, cross the gap!

• sheet music (with melody play-back)

Songs like this one can be used during class meetings and/or in homework assignments. Either way, the song will be most impactful if students DO something with it, as opposed to just listening.

An initial, simple follow-up activity could be to answer the study questions below. A more extensive interaction with the song might entail (A) learning to sing it, using an audio file and/or sheet music as a guide, and/or (B) illustrating it with pictures, bodily poses, and/or bodily movements. The latter activity could begin with students identifying the most important or most challenging content of the song, and deciding how to illustrate that particular content.

(1) What is the difference between a connexin and a connexon?

(2) What is the difference between a connexon and a gap junction?

(3) Is the diameter of the pore of a gap junction larger or smaller than that of a Na⁺ or K⁺ channel?

(4) How do electrical synapses differ from chemical synapses?