My summer research project has two major components. Both components use a tetracycline-controlled transcriptional activation system, a system designed to control transgene expression. The system can be designed so that the addition of tetracycline turns on expression or turns off expression, giving the systems the names Tet-On and Tet-Off, respectively. In this experiment, I will be using the Tet-On system. In a Tet system, the tetracycline transactivator (tTA) must be bound to an operator sequence on the DNA in order for transcription to occur. In the case of Tet-On, the tTA is only able to bind to the operator when also bound to tetracycline or a tetracycline derivative such as doxycycline. The addition of the doxycycline allows transcription to begin, giving very tight temporal control.
Comments
A little wordy - turns on
A little wordy - turns on expression or turns off expression
Wordy and lack of topic sentence
I agree, it's a little wordy at times, turn "turns on expression or turns off expression" to "turns expression on or off." A topic sentence would be nice, it seems like you just jumped into the paragraph.
Comment
I agree with others that it is a bit wordy. I think you could break the third sentence into the paragraph into two. You could even explain what are the effects of the expression being on or off. Overall, this is an interesting topic.