Hormonal Influences On Growth

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  • Hormonal Influences On Growth
    • Humans
      • Human Growth Hormone
        • Produced by the pituitary gland
        • promotes growth by accelerating amino acid transport into the cells of tissues and bones
        • allows rapid synthesis of proteins
        • Allows increase in length of bones during growing years
      • Thyroid Stimulating Hormone
        • Produced by the pituitary gland
        • Controls growth and activity of thyroid gland
        • Thyroid responds by producing thyroxine
        • thyroxine regulates the bodys metabolic processes
    • Plants
      • auxins
        • the shoot tip is essential for growth and produses a chemical
          • this chemical diffuses down the lower regions of the shoot where it stimulates growth by making cells ellongate
        • can diffuse through agar or gelatin
          • but not through metal
        • most common is IAA
          • IAA
            • Hormonal Influences On Growth
              • Humans
                • Human Growth Hormone
                  • promotes growth by accelerating amino acid transport into the cells of tissues and bones
                  • allows rapid synthesis of proteins
                  • Allows increase in length of bones during growing years
                • Thyroid Stimulating Hormone
                  • Controls growth and activity of thyroid gland
                  • Thyroid responds by producing thyroxine
                  • thyroxine regulates the bodys metabolic processes
              • Plants
                • auxins
                  • the shoot tip is essential for growth and produses a chemical
                    • this chemical diffuses down the lower regions of the shoot where it stimulates growth by making cells ellongate
                  • can diffuse through agar or gelatin
                    • but not through metal
                  • most common is IAA
                    • IAA
                      • produced in root, shoot and leaf meristems
                      • moves short decisions by diffusion
                      • long distance occurs in phloem by translocation
                      • Effects of IAA
                        • Organ Level
                          • Shoot and root growth
                          • Growth Culture
                            • Phototropism
                              • When an organ bends towards the source of light
                              • High conc. of auxins found on the non-illuminated side
                            • Apical Dominance
                              • Very High conc. of auxins inhibit growth
                              • In some plants the apical bud inhibits growth of lateral bud
                              • Gardeners often remove the apical bud
                            • Leaf Abcission & Fruit formation
                              • Auxins promote the formation of the fruit coat from the ovary wall
                              • Abcissions is the seperation of leaves or fruit from a plant
                              • Prior to this auxin conc. drops & a thin abcission layer of cells is formed at the base of the leaf or fruit stalk
                        • Cell Level
                          • Cell Division
                            • stimulates cell division in apical meristems
                            • Transported from apical meristems to cambium when it stimulates secondary growth
                          • Cell Elongation
                            • In apical and lateral meristems
                            • promotes elongation by increasing the plasticity of the cell walls
                              • this enables them to tretch irreversibly when water enters by osmosis
              • Commercial Applications
                • Parthenocarpy
                  • fruit development without fertilisation to produce seedless fruit
                • Delayed Abcission of fruit
                  • crops sprayed with synthetic auxin
                    • ensures fruit is ripe
                • Rooting Powders
                  • contain synthetic auxin which stimulates root growth and allows progation
                • Herbicides
                  • kills weeds by exhausting them
                  • stimulates the plants rate of growth & metabolism
                  • plant uses all of its food reserves & dies of starvation
              • Giberellins
                • secreted by a fungus called gibberela
                • giberellin stimulates cell division an elongation
                • Stages Of Action
                  • 1. Giberellin produced in embryo
                  • 2. Gib. passes into aleurone Layer
                  • 3. Gib. activates gene which produces ?- amylase
                  • 4. ?-amylase brakes down starch to sugar
                  • 5. sugar provides energy for growth
                  • 5. Gib. has broken the dormancy of the seed
            • produced in root, shoot and leaf meristems
            • moves short decisions by diffusion
            • long distance occurs in phloem by translocation
            • Effects of IAA
              • Organ Level
                • Shoot and root growth
                • Growth Culture
                  • Phototropism
                    • When an organ bends towards the source of light
                    • High conc. of auxins found on the non-illuminated side
                  • Apical Dominance
                    • Very High conc. of auxins inhibit growth
                    • In some plants the apical bud inhibits growth of lateral bud
                    • Gardeners often remove the apical bud
                  • Leaf Abcission & Fruit formation
                    • Auxins promote the formation of the fruit coat from the ovary wall
                    • Abcissions is the seperation of leaves or fruit from a plant
                    • Prior to this auxin conc. drops & a thin abcission layer of cells is formed at the base of the leaf or fruit stalk
              • Cell Level
                • Cell Division
                  • stimulates cell division in apical meristems
                  • Transported from apical meristems to cambium when it stimulates secondary growth
                • Cell Elongation
                  • In apical and lateral meristems
                  • promotes elongation by increasing the plasticity of the cell walls
                    • this enables them to tretch irreversibly when water enters by osmosis
    • Commercial Applications
      • Parthenocarpy
        • fruit development without fertilisation to produce seedless fruit
      • Delayed Abcission of fruit
        • crops sprayed with synthetic auxin
          • ensures fruit is ripe
      • Rooting Powders
        • contain synthetic auxin which stimulates root growth and allows progation
      • Herbicides
        • kills weeds by exhausting them
        • stimulates the plants rate of growth & metabolism
        • plant uses all of its food reserves & dies of starvation
    • Giberellins
      • secreted by a fungus called gibberela
      • giberellin stimulates cell division an elongation
      • Stages Of Action
        • 1. Giberellin produced in embryo
        • 2. Gib. passes into aleurone Layer
        • 3. Gib. activates gene which produces ?- amylase
        • 4. ?-amylase brakes down starch to sugar
        • 5. sugar provides energy for growth
        • 5. Gib. has broken the dormancy of the seed

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