Lecture 15 Taproot Storage root Plants have three tissue types Dermal tissue epidermis guard cells control gases trichomes root hairs Vascular tissue Function transport fluids and minerals signal molecules sugars Xylem Phloem Ground tissue everything else Plant tips grow indeterminately from the apical meristem Root apical meristem Root cap protects root tissue Grow vertically into the ground Shoot apical meristem Contained in the terminal bud Grow up Primary growth Vascular plants The lengthening of roots and shoots Vascular cambium and cork cambium thicken the stem and root Lateral meristems increase plant girth Secondary growth The thickening of the stem and root Vascular cambium makes new vascular tissue Thickens the stem by producing secondary xylem and secondary phloem Produces either a new xylem towards the inside or the stem or root Or a new phloem cell toward the outside Vascular tissue is used for transport Xylem dead open cell walls contains no more plasma membrane Tracheids vessel members Tracheids are spindle shaped cells found in gymnosperms Vessel embers are found in angiosperms Transporting water and minerals from the roots Phloem Sieve tube elements miss a lot of the things necessary to continue Companion cells contains all organelles life support for elements Sieve tube elements companion cells Transports carbohydrates and other materials from a source to the tissues sink Transpiration Source is where something is being produced Sink is where things are being stored transported to Evaporation of water from the leaves and the stems of the plant Driven by heat from the sun Helps pull water inside the roots up the stem and to the leaves Provides force Move minerals in which leads to a greater solute concentration inside leads to water rushing Cellular processes aid transport Water is polar and cannot get into the cell easily Aquaporin are used for the transport of water Water moves by osmosis Moves from a high concentration to a low concentration into the cell Ions need ion channels Plant roots have a proton pump Active transport requires ATP Pump protons against concentration gradient Potassium enters by diffusion to balance charges Protons then pull in chloride ions through a symport protein Once cell has all of these ions water flows in by osmosis There are two pathways to enter plant roots Apoplast no membrane transport fast lane Moves through cell walls and intracellular spaces non living material Unregulated until you reach casparian strip cannot move through Must go through plasma membrane be selected for to get around casparian strip Symplast plasmodesmata and membrane transport Much slower Moves through plasmodesmata pores through cell wall and plasma membrane Regulated pass right through casparian strip To move into xylem water and minerals move into the symplast Casparian strip Waxy layer that goes through the cell wall Prevents minerals and ions from moving through it Endodermis Pericycle Root pressure Adhesion Water moves from roots to leaves in four ways Exerted by the root tissue and forces water up the xylem Water sticking to the walls of the xylem Due to hydrogen bonding Cohesion Water sticking to itself Due to hydrogen bonding Transpiration Occurs at the leaves Pressure flow uses phloem loading for transport Moves by positive pressure through sieve tubes Transport of sucrose solutes and other substances Loading Unloading From the source into the phloem From the phloem and into the sink Moves into phloem by active transport Proton pump Once into the phloem moves due to water movement Plants respond to abiotic and biotic factors Abiotic non living Water sunlight storms Biotic living Other organisms parasites Plants have mechanical defenses against herbivores Trichomes Sticky projections hairs Thorns spines Latex Traps organism very sticky Ant acacia symbiosis Ants sting predators Hollow thorns where ants live Secrete substances that ants can eat Plants have chemical defenses against herbivores Sequestration Accumulating a compound that the plant is producing Compound placed inside vesicles storage Can keep in an inactive form until release is necessary Chemicals can affect almost every system in an organism Table 39 1 Ouabain Sodium potassium pump inhibitor Plants respond to damage by herbivores Signal transduction Second messenger pathway Jasmonic acid Binds to a receptor on thep hloem companion cell Activates causing jasmonate to be formed Jasmonate goes through plasmodesmata into sieve tube elements Enters a mesophyll cell found in shoots where leaves are being damaged Respond to jasmonate by forming a transcription factor Salicylic acid proteinase inhibitors Transcription factor Adaptations to land Reproductive differences Sporophyte dominant vs small gametophyte Mosses hornworts liverworts haploid gametophyte dominant Everything else diploid sporophyte dominant Flagellated vs non flagellated sperm and pollen Flagellated sperm in mosses and ferns Non flagellated sperm and pollen in gymnosperms and angiosperms seed plants Egg vs embryo on parent seeds fruits Retention on embryo Some in plantae don t have retention Seed plants Reproductive Innovations Pollen Seed provides protection to embryo Consists of food source and embryo Angiosperms have an outer coat Gymnosperms do not have an outer coat Flowers pollinators and genetic variation Seen in angiosperms Flowers evolved with pollinators form relationships Fruits seed dispersal Seen in angiosperms Wind Water coconuts Animals Alternation of generations Sporophyte dominate Gametophyte production Microscopic Male microspore Female megaspore Pollination Angiosperms reproduce using the flower Pollen hitting to the stigma of the female portion of the plant Just because pollination occurs doesn t mean you will have fertilization Fertilization Sperm and egg meet fusion Seed formation Occurs after fertilization Heterosporous Can tell the difference between male and female spores Flowers contain plant reproductive organs Stamen male portion of the flower Where the microsporangia will be Sits on filament Pollen spores are produced in the anther Anther Filament Holds up anther Carpel female portion of the flower pistal Stigma Style Ovary Ovule Very top sticky portion Center holds up stigma Contains the ovule Petals Portions of the plant that attract pollinators enhance pollination Megasporangia Corolla Calyx Sepal Green portion around petals Protective Flowers are modified leaves Flowers produce