BI110 Chapter Notes - Chapter 1: Circadian Rhythm, Phytochrome, Conjugated System
Document Summary
Uses light for both energy & info. Eyespot: light sensor (determines whether to move toward or away from light, chloroplasts harvest light and use it as energy ex: photosynthesis) The sun reason why there"s life on earth. Sun produces electromagnetic radiation which gets absorbed by pigments in molecules in organisms. Length of wave determines kind of electromagnetic radiation. Light: er that humans can detect with their eyes. A photon is a wave of discrete particles. Light energy must be absorbed by molecules called pigments. The light reflects, absorbs or transmits depending on the pigment. Pigment: a conjugated system with alternating single and double bonds which enables electrons to become delocalized and therefore can interact more freely with photons. An electron is promoted to a higher/lower energy state when photos are absorbed. The difference between the ground state and higher energy state equals the amount of energy the photon supplies that ends up being absorbed.
