BISC208 Lecture Notes - Lecture 7: Indole-3-Acetic Acid, Coleoptile, Phototropism
21 Mar 2019
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Document Summary
Sensory cells receive an external signal and change it into an intracellular signal. The sensory cells then send a signal to target cells in other parts of the plant body. Target cells receive the signal an archeage their activity to produce an appropriate response. Received by a sensory cell and it must be changed into a form that is meaningful to a cell. Signal receptor proteins change shape in response to an environmental stimulus. Darwin and his son francis experimented with coleoptiles - modified leaves that form a sheath protecting emerging grass shoots. Germinated seeds in the dark and placed young, straight coleoptiles next to a light source. Grew towards the light due to elongation of cells on the shaded side of plant. Direct movement in response to light is phototropism. Found plants bend toward light that includes blue wavelength. Later identified as indole acetic acid (iaa) Auxin binding proteins are found in the stem and leaf.
