Lecture 30 Biology 2

Lecture 30 Biology 2 - Lecture 30, Plant Hormones March 31,...

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Lecture 30, Plant Hormones March 31, 2008 1 Chapter 39: Plant responses to internal and external signals 1. Signal transduction pathways 2. Plant hormones 3. Responses to light 4. Responses to other stimuli 5. Herbivores and pathogens What makes fruit ripen? What makes leaves fall? Environmental stimulus Internal response: plant adjusts pattern of growth and development Canola ( Brassica sp.) 1. Signal transduction pathways Cellular receptor b signal transduction pathway b response
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Lecture 30, Plant Hormones March 31, 2008 2 Signal transduction pathways Cellular receptor b signal transduction pathway b response Example: de-etiolation (“greening”) Light detected by phytochrome (photoreceptor) b Second messengers (cyclic GMP and Ca 2+ ) b Transcription, translation, post-translational modification to produce “greening” proteins Potato in the dark Potato exposed to light Cel wal CYTOPLASM Reception Transduction Response Second messenger produced Light Plasma membrane Specific protein kinase 1 activated cGMP Phytochrome activated by light NUCLEUS Specific protein kinase 2 activated Ca 2+ channel opened Ca 2+ Transcription factor 1 Transcription factor 2 Transcription Translation De-etiolation (greening) response proteins Signal transduction pathways hormone : Greek verb: “to excite” Hormones are found in all multicellular organisms Chemical signals that coordinate different parts of an organism Produced by one part of the body, transported to another part of body where it triggers response Very small amounts required 2. Plant hormones Positive phototropism: shoots grow toward light
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Lecture 30, Plant Hormones March 31, 2008 3 Plant hormones Darwin & Darwin: response occurred only when light reached the tip of the coleoptile Concluded that tip of coleoptile sensed light • Growth response occurred below tip Early experiments
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This note was uploaded on 03/31/2008 for the course EBIO 1220 taught by Professor Demig-addams during the Spring '07 term at Colorado.

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Lecture 30 Biology 2 - Lecture 30, Plant Hormones March 31,...

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