test 3 - Plant responses to the Environment: light...

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Plant responses to the Environment: light phytochrome, touch, herbivory 1) Light a. Spectrum Blue purple red=most effective for photosynthesis b. Plants grow towards light c. Seeding germination depend on light (red=germinates) far red=does not germinate d. Phytochrome=a reversible receptor i. Red light activates phytochrome=photosynthesis occur ii. Color blinds=lacks receptors. e. Shade Avoidance i. Growing in shade under a plant grows only tall not wide./ competes with other plants 2) Touch a. Wind=shorter. b. When touched leaves fold and releases acids c. Bad touch: herbivory i. Systemin=Jacsmonic acid—volatile gas chemical/plants warn other plants/ make it difficult to digest=protease inhibitor ii. Insect saliva can let plants know which insect is attacking iii. Plants release several volatile chemicals to signal other organisms Plants grown in dark=tall Short day plants/ long day plants Plants use day length to synchronize flowering. WRONG Critical period is actually night length Phytochrom regulates flowering time.and sets circadian clock. -Responses: Seed germination, flowering, photo morphogenesis, leaf expansion, chloroplast development, stem elongation Plants use night length to determine the season Circadian clock is unknown/ daily patterns set by light. Light input oscillator output Input=resets clock/ light dark cycle, shows no pattern Oscillator=central pacemaker that generates the oscillation/sets patterns in light/dark cycle. Output=translates oscillation into behavioral and physiological rhythms CCA1=transcription factor that regulates some photosynthetic genes. Overexpression of CCA1 in transgenic Arabidopsis plants abolished the circadian rhythms of several genes with dramatically different phases. No CCA1 protein, phytochrome induction of Lhcb RNA is reduced. Part of oscillator, but not the oscillator clock Plants were created that lack of functional CCA1 gene Plants overexpression CCA1 delayed flowering Leaf movement rhythms were abolished. Plant Reproduction Outside flower=petal=how animals recognize flower Male parts=Stamen a. Anther=pollens b. Filament Female parts= Carpel a. stigma=pollen lands b. style=long tube connecting c. ovary=contains egg 3 Nuclei i) Pollen tube=pollen extend cell/ can grow long ii)) sperm fuse with egg=zygote=develops into embryo surrounded by endosperm and seed coat=seed iii) polar nuclei=endosperm/ haploid, triploid (Nutrients) Seed must contain enough nutrients to nourish the embryo until it can begin photosynthesis Seed size= good indicator of how much energy is stored to support early seeding growth. Fruits=animals can get nutrients to disperse seeds. Ex. Capsacin is a deterrent to seed eating mammals. -mice(seed predator) doesn’t eat Capsacin bc of spice
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This note was uploaded on 06/16/2009 for the course BIO 53665 taught by Professor Iverson during the Spring '07 term at University of Texas at Austin.

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test 3 - Plant responses to the Environment: light...

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