BY 124 1st Edition Lecture 6 Outline of Last Lecture Chapter 36I. Transpirational Pull Cohesion-Adhesion MechanismII. Mechanisms of Stomatal Opening and ClosingIII. Movement Through PhloemIV. Sieve TubesChapter 37I. Essential Elements in PlantsII. Cation ExchangeIII. Soil Bacteria and NitrogenIV. Plants That Have Relationships With Another OrganismV. Nutritional Adaptations in PlantsOutline of Current Lecture Chapter 37I. Nutritional Adaptations in Plants (cont.)Chapter 39I. Signal Transduction PathwayII. Example of STPIII. Plant HormonesIV. Plant MovementCurrent LectureChapter 37 (cont.)I. Nutritional Adaptations in Plants (cont.)a. Carnivorous plants (insectivorous)1. Live in Nitrogen-poor soils, therefore have to get nitrogen from exoskeleton of insects2. Usually found in sandy soils (along coast)1. Pitcher plantsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Modified leaves, downward pointing hairsb. Water/nectar in “pitcher”c. Insect cannot get out once in due to the downward pointing hairs2. Venus fly trapsa. Proton pumps cause “trap” to open/close3. Sundewsa. Use sticky substances/protrusions to trap insect and then another protrusion releases chitin to get nitrogen 4. Bladderwortsa. Float on surface of waterb. Aquatic insect triggers trap, water is sucked into bladder of plant, insect is pulled in with it and will then remain there to be broken downChapter 39: Plant Responses to Internal and External Signals Remember: hormone – to excite or respondI. Signal Transduction Pathway (Figure in Chapter Review of 39.1)a. Receptioni. Hormone binds to receptor1. Small because it needs to get through the cell wallb. Transductioni. Relay proteins and messengers pass infoc. Responsei. Activation of cellular responsesII. Example of Signal Transduction (Figure 39.4)a. Remember: kinases phosphorylateb. Small amounts of hormones can still give good responsec. How hormone responds in plants depends on:i. Site of actionii. Size of embryoiii. Concentration of hormoneiv. Ratio of hormone compared to other hormonesIII. Plant Hormonesa. Auxin (IAA) – “to grow,” any organism that will elongate effects coleoptilesi. IAA (indoleacetic acid) – most important type/form of auxinii. Experiments (Figures 39.5 and 39.6)1. Darwin and Darwin (1880)a. If tip taken off – doesn’t respond to light b. If opaque cap – no response to lightc. Transparent cap – responds to lightd. Opaque shield on curve/stem – responds to light2. Boysen-Jensen (1913)a. Gelatin put all across the cut-off tip – responds due to the permeability of the gelatinb. Mica put all across the cut-off tip- does not respond due tothe impermeability of the micaiii. Polar Auxin Transport (Chemiosmosis)1. Carriers for auxin are located at the base of the cell2. Auxin travels cell to cell in coleoptile3. When -A (negatively charged auxin molecule) moves through transport carrier, it picks up H+ and becomes AH.a. This allows it to move a little more freely in the membrane4. Loses H+ when it leaves the cell membranea. ATP puts the H+ back into cell membrane5.-A moves to base of cell and repeats processiv. Figure 39.8 shows how plant bends in response to light because of auxinv. Growing patterns 1. Phototropism – moves in response to light2. Gravitropism – moves in response to gravity (Figure 39.24)a. Statoliths settle and dictate how the plant will rootvi. Prevents lateral buds (Figure 39.9)1. Auxins keep potatoes from budding2. Fruit only occurs after fertilization a. Auxin produces a fruit without seedsvii. Leaf Abscission – auxin retards1. This is what happens when a plant “seals off” leaf by cutting off supply viii. Involved in secondary growthix. Helps with growth of lateral and adventitious rootsx. Affects vascular cambiumb. Gibberellins – fungus, “foolish seed disease”i. Forms long shootsii. Stimulates fruit developmentiii. Cause embryos to make alpha-amylase to break down starch to make sugar for baby plant to growc. Brassinosteroids – like cholesterol i. Reduce cell elongation and divisiond. Cytokinins – come from rootsi. Degradation products of nucleic acids1. Modified forms of adenineii. Most important: zeatin (comes from corn)iii. Causes cell divisioniv. Work by causing transcription and translationv. Work with auxins1. If auxin decreases and cytokinins increases – shoot and leaf growth2. If auxin ↑ and cytokinins ↓ - root growth 3. If auxin= cytokinins – growth but no differentiation vi. Anti-aginge. Abscisic acid (ABA)i. Inhibits growth, inhibits division in vascular cambiumii. Stomata close hen plant is stressediii. Causes leaves to fall offf. Ethylene – stress hormonei. Triggered by auxin and ABAii. Speeds ripening/ rotting processiii. Promote leaf abscissioniv. Inhibits root elongationv. Flowering vi. Leads to changes that cause death in plant1. Apoptosisa. Like xylem/ found in xylemIV. Plant Movement (Figure 39.25)a. Phototropismb. Gravitropismc. Thigmotropism- growth by touchi. Thigmomorphogenesis – “if I’m touching you, I’m going to affect your