BIOL 206 Lecture Notes - Lecture 25: Phototropin, Signal Transduction, Radicle
Document Summary
Sensing & responding to the environment plant adaptations. A sessile organism must respond to their changing environment: external signals are used by plant cells to alter their physiology, morphology and development. Biological environment: plants receive signals at the cell level, and have no well-defined sensory organs, except for gravity, all other signals are constantly variable, example: seed germination. External signals: water, light, temperature, fire, etc. Internal signals (seeds have a negative water potential) Major steps: take up water (imbibition, liberate stored nutrients, growth* of embryo results in emergence of root radicle. Two classes of plant molecules are involved in signal transduction: photoreceptors. Respond to both the quality and intensity of light. Different kinds produced by any one plant cell. Light is one of the most important cues regulating plant function: phototropins respond to blue light, phytochromes respond to red light. Blue light activates phototropin for phototropism (directional shoot elongation: phototropin receptors are also important in regulating.
