BIOL 2010 Lecture Notes - Lecture 10: Stoma, Water Conservation, Mitosis
2 Dec 2016
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Hormones - production dictated by genes: mostly produced in actively growing regions, produced and active in smaller amounts than vitamins and enzymes. Hormones act by chemically binding to specific receptors. Triggers series of biochemical events, including turning genes on and off. Major types of hormones: auxins, gibberellins, cytokinins, abscisic acid, ethylene. Auxin production occurs mainly in apical meristems, buds, young leaves and actively growing parts of plants. Plant responses vary according to concentration, location, and other factors. Generally, monocots less sensitive than eudicots and shoots less sensitive than roots. Stimulate enlargement of cells by increasing cell wall plasticity. Promote cell enlargement and stem growth, cell division in cambium, initiation of roots and differentiation of cell. Delay development processes such as fruit and leaf abscission, and fruit ripening. Movement of auxins from cells where they originate requires energy expenditure. Movement is polar - away from source, usually from a stem tip towards the base.
