EnvReg213-page12 - Plant Environmental Regulators - 12...

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Plant Environmental Regulators - 12 Activities that occur seasonally, as opposed to daily, are referred to as photoperiodism (responses to changing day or night length) and are regulated by internal biological clocks in both plants and animals. Photoperiodism involves the biological clock’s ability to sense changing day length and seasons. Phytochrome can detect such changes since there is a burst of Pfr synthesis at daylight. This burst can be used to reset the plant's biological clock daily. Biological clocks can also involve temperature cycles. Setting biological clocks in any organism involves genetic controls with feedback mechanisms that ensure that the biological clock “keeps time”. A transcription factor that inhibits the gene that codes for the transcription factor is a likely clock-setter. As the transcription factor accumulates it inhibits itself. If the transcription factor concentration declines, the gene is activated and more protein product accumulates.
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This note was uploaded on 01/08/2012 for the course BIO 213 taught by Professor Makina during the Fall '09 term at SUNY Stony Brook.

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