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Phototransduction

by Greg Crowther


Context

This is a call-and-response song (students can sing the lines in parentheses) written for BBio 351 at UW-Bothell. It is about the signaling cascade leading from absorption of photons by photoreceptors to changes in the membrane potential of these photoreceptors. Students can be asked to sing extra-loudly on the steps that represent amplification of the initial signal.


Lyrics

Waiting in the dark --
Sodium gates agape --
A rod receives a spark;
Retinal changes shape....

And rhodopsin is rockin' trimeric G.
(Rhodopsin is rockin' trimeric G.)
The G protein activates a PDE.
(The G protein activates a PDE.)
Diesterase depletes cyclic GMP.
(Diesterase depletes cyclic GMP.)
Then the dark current's less than what it used to be!
(The dark current's less than what it used to be!)


Other Files

MP3 (demo)

sheet music (with melody play-back)


Lesson Plan

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 the audio file and/or sheet music as a guide, or (B) designing kinesthetic movements ("dance moves") to embody it. The latter activity should begin with students identifying the most important or most challenging content of the song, and deciding how to illustrate that particular content.


Study Questions

(1) What is meant by the phrase "sodium gates agape"?

(2) What is the relationship between retinal and rhodopsin?

(3) What is meant by the line "rhodopsin is rockin' trimeric G"?

(4) What does PDE stand for?

(5) What chemical reaction does phosphodiesterase catalyze?

(6) What is a dark current?

(7) Does absorption of light depolarize or hyperpolarize the membrane potential? Why?

(Answers may be found on the answers page.)