Review: Plant Behaviors and Worms

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BIOL 1115
Melissa Mc Elligott

BIOLOGY TEST #3 PLANT BEHAVIORS ○ Tropisms: plants grow toward/away from a uni-directional stimulus ■ (+) towards stim. ■ (-) away from stim. 1. Heliotropism - sun a. Diurnal motion - “Sun Tracking”: motor cells (K+ pump; turgor pressure; allow plants to move) 2. Phototropism - light a. plant grows and bends toward light (auxin migrates to shady side of stem, cells on shady side elongate faster than cells on sunny side) 3. Gravitropism - gravity a. statoliths (starchAuxin granule) responsible for: (+) roots, (-) shoots 4. Thigmotropism a. touch/environmental stim. (wind, rain) b. thigmomorphogenesis: entire plant responds to stimulus ○ Photoperiodism: ability to measure/respond to the length of day & light (seasons) ● pigments that detect photoperiod 1. Phytochromes (red light) 2. Cryptochromes/Phototropin(blue light) ■ Short day plants - flower during fall/winter (short days) ■ Long day plants - spring/summer bloom ■ Day neutral - not dependant on day length ○ Nastic (Nutational) Movements i. do not depend on stimulant direction ● quick movement ■ seismonastic movement: touch, shaking, thermal stim. ■ sleep movements (response to light and dark changes) - caused by Potassium (K) Pump [Turgor Pressure] PLANT HORMONES ○ all plant communication is through hormones ○ travels within phloem (response to appropriate stim.) ○ synthesized in 1 part of the plant ■ 5 common recognized Groups - 1. Auxins: (Master Plant Hormones) - structure, development, behavior a. produced in shoot apical meristem b. prevent growth of axillary buds - Apical Dominance (resources shifted, which inhibits another function) c. promotes fruit growth d. inhibits leaf/fruit drop e. mediates phototropism f. used in sol. causes rapid growth in roots (fertilizer) - 2. Cytokinins i. promote cell division (cytokinesis) ii. derivatives of adenine (root tips) 1. prevents senescence - process of aging 2. initiate growth Gibberellins (acid) - cell elongation - promotes growth - produced in the apical buds, roots, young leaves, seed embryos - functions: flowering, retards leaf/fruit drop, seed germination - 3.Ethylene -promotes abscission (leaf and fruit drop) -ripening material -hydrocarbon gas - 4. AbscisicAcid (ABA) -protects seed and buds, initiates and maintains seed and bud dormancy -Slows things down (creates dormancy period) -stimulates bud scale formation -brings about closure of stomata a. Turgor response -> opening and closing of stomata (water moves in and out of guard cells) - 5. Brassinosteriods ■ chemically related to animal steroid hormones ■ Receptors: Plasma Membrane kinases (not nucleus) i. promotes cell & shoot elongation ii. xylem development iii. retards leaf drop iv. stress responses v. can be applied to protect plants (heat, cold, salinity, etc) 1. allow plants to survive in harsher environments ● Primary Metabolites: pathways by which plants make required materials ● Secondary Metabolites: Phenolics,Alkaloids, Terpenoids, Polyketides ■ synthesis of molecules not essential for cell struct./growth ■ chemicals that lead to survival and reproduction (not materials necessary for normal homeostasis -> not essential for cell structure and growth) ■ Increase fitness ■ Common in plants and stationary organisms (means of defense) ■ Increase survivability and reproduction ■ Useful in creating pharmaceutical agents CATEGORIES (4) 1. Phenolics - antioxidants w/ intense flavors/smells (vanilla, chocolate) 2. Alkaloids - bitter tasting molecules for defense (caffeine, nicotine) 3. Terpenoids - intense smells and colors (cinnamon, mint, THC) 4. Polyketides - chemical weapons (antibiotics, tetrodotoxin[octopus]) INVERTEBRATES ● Kingdom Animalia ○ Common Characteristics ■ Heterotroph ■ multicellular ■ nervous tissue ■ muscle tissue ■ sexual reproduction ■ extracellular matrix: collagen ■ Hox genes: clusters of genes that determine the anterior/posterior access to the animal’s body ■ segmentation (body built of repeated units) - metamerism (linear series of body segments) ■ Cell junctions: ● Anchoring: hold cells together ● Tight: form impermeable barriers, regulate passage of material ● Gap: key in communication ○ Invertebrates ■ no backbone ■ 97-99% of all animals ■ negative characteristic ○ Vertebrates ■ have backbone (positive characteristic) ■ 1% of all animals ■ 1 phylum (Chordata) ○ Classification Criteria i. diplobastic (2 layers) 1. endoderm 2. ectoderm ii. triploblastic (3 layers) 1. endoderm 2. mesoderm 3. ectoderm ■ level of organization (cellular, tissue, organ) ● cellular - division of labor ● Tissue - similar cells arranged in a pattern with a common function ○ epithelial ○ connective ○ muscular ○ nervous ● Organ - tissues arranged into organs ● Organ system - groups of organs to perform function ○ 11 body systems ■ integumentary, nervous, urinary, skeletal, digestive, circulatory, endocrine, muscular, respiratory, immune, reproductive ■ Body plan (sac, pseudocoelom, etc.) ■ segmentation (repetition of units lead to specialization) ○ Two types of symmetry ■ Radial - 2 identical halves from multiple angles ■ Bilateral - definite right and left halves (Cephalization - formation of a distinct head) ○ Type of Coelom - fluid filled body (between gut and body wall) in which organs can be suspended ● benefits: more space, surface area, storage, support, body size, and complexity ■ acoelomate (flatworms) ■ pseudocoelomate (roundworms) ■ coelomate (molluscs) - mesoderm lined gut ○ Early developmental pattern ■ Protostome - first embryonic opening is the mouth ● 8-cell stage is spiral (cells divide at 45 angles) ● blastospore becomes mouth ● coelom forms by splitting of mesoderm (schizocoelom) ● Determinate cleavage: fate of cells is determined early on (if you take out a cell the embryo will fail to develop -> cells already programmed) ■ Deuterostome - 2nd embryonic opening is theomouth (chordates) ● 8-cell stage is radial (cells divide at 90 angles) ● blastospore becomes anus ● coelom forms by outpocketing of gut (cells pinch off -> enterocoelom) ● Indeterminate cleavage: regulative embryo, fate of cells is not determined early on (if you take out a cell the embryo will continue to develop -> multiple embryos will develop) - (Both have identical coelom structure) ■ •Blastula stage: involves hollow ball of cells (rapid cell division) •Blastocoel: fluid filled chamber, creates coelom •Gastrula stage: two layers of cells (endoderm and ectoderm) •Zygote -> Blastula -> Gastrula a. lophotrochozoa - trochophore (early embryonic/larval stage), lophophore (feeding tentacles) b. ecdysozoa - molting ○ PHYLUM: Porifera (sponges) ■ only level of animal to have “cellular” organization ■ Ostia - pores of the sponge ■ Choanocytes - beating flagella; produces water currents that flow through pores (into central cavity, out of osculum); line interior of sponge (“collar cells”) ■ sessile filter feeders - phagocytosis (intracellular digestion) ■ spongin - the equivalent of collagen protein in animals; structure/flexibility ■ mesohyl - nonliving connective tissue ■ spicules: provide structure (CaCO3) ■ Totipotent cells: have capacity for regeneration (ex: archaeocytes) ■ Pinacocyte: outermost layer of cells (similar to epidermis) ■ Spongocoel: inner cavity ■ Gemmules: tough, protective coating in freshwater sponges (allow sponges to tolerate harsh winter conditions) -> will generate new sponges when conditions are favorable ○ 3 types of sponges ■ Asconoid - simple ■ Syconoid - medium ■ Leuconoid - complex ○ Marine Natural Products ■ secondary metabolites - often play a role in defense; human use in medicines ■ mutualistic relationship between bacteria and sponges ■ Article: ○ PHYLUM: Cnidaria ■ tissue level of organization: diploblastic ■ radial symmetry ■ 2 body forms (homologous structures) ● polyp ● medusa ■ Polymorphism (dimorphism): 2 distinct body forms ■ Cnidocytes - specialized stinging cells used for feeding and defense ● have nematocyst - fluid-filled capsule that houses harpoon
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