Okazaki Fragments

by Greg Crowther

This song, originally written for Biology 311 (Genetics) at the University of Puget Sound, is about DNA replication by the enzyme DNA polymerase. Its music underscores the difference between the leading strand (synthesized as one long, continuous piece of DNA, and sung as one long, continuous vocal line) and the Okazaki fragments of the lagging strand (synthesized and sung in pieces until joined together by DNA ligase).

CHORUS:
The leading strand elongates toward
(Okazaki!)
The moving replication fork;
(Okazaki!)
Continuously it extends
(Okazaki joined by ligase!)
Out from the primer to the end.
(Okazaki joined by ligase!)

Reiji Okazaki, working in Japan,
Studied replicating DNA.
Tritiated thymidine helped him understand
The two new strands are built in different ways.

CHORUS

The labeled DNA strands were long and short as well
Following a fifteen-second pulse.
The replication process occurring in the cells
Must be semidiscontinuous!

CHORUS (twice)

• 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 tritiated thymidine?

(2) What does it mean to say that DNA replication is "semidiscontinuous"?

(3) What was the experimental evidence that DNA replication is semidiscontinuous?