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PLANTS

PLANTS. Chapters 9 , 32. PHOTOSYNTHESIS: Biological process that captures light energy and transforms it into the chemical energy of organic molecules, which are manufactured from CO 2 and H 2 O. 3Co 2 + 3 H 2 0 C 3 H 6 O 3 + 3 O 2.

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PLANTS

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  1. PLANTS Chapters 9, 32

  2. PHOTOSYNTHESIS: Biological process that captures light energy and transforms it into the chemical energy of organic molecules, which are manufactured from CO2 and H2O 3Co2 + 3 H20 C3H6O3 + 3 O2 • *Very little glucose is stored in plants • Mostly find sucrose • and starches in plants PHOTOSYNTHESIS EQUATION: /enzyme CELLULAR RESPIRATION EQUATION: + enzyme + ATP

  3. *Very little glucose is stored in plants; Mostly find sucrose and starches in plants FYI… Review… Dehydration Synthesis Glycosidic Linkages ? Alpha/Beta Linkages? Starch/cellulose? ?

  4. “Flipped chimneys” *H-bonds

  5. Ecology-Food Web/Trophic Connection Major Photoautotrophs? Plants, Algae/Phytoplankton, Cyanobacteria (~2.6bya)

  6. “The Cycle of Life”

  7. Stages of Photosynthesis • STAGE 1: Capturing Light Energy (Light Reactions or LightDependent Reactions)…on the Thylakoid Membrane • Energy is captured from sunlight (chloroplasts) • Stage 2: Using Light Energy to make ATP and NADPH • ATP = Major Energy Molecule • NADPH = Energy Carrier • Supplies energy needed to drive Stage 3 • Thylakoid Membrane • Stage 3: Calvin Cycle (‘Dark’ Reactions or Light Independent Reactions) • The ATP and NADPH are used to power the manufacture of energy-rich carbohydrates using CO2 from air…..Stroma of the chloroplast

  8. 3 Double–Membrane Organelles? Stage 2 Stage 3 Stage 1 • Chloroplast, Mitochondria, Nucleus

  9. *Double Membrane: Chloroplast and Thylakoid STROMA

  10. The innermost membrane of the chloroplast is called the thylakoid membrane.(*double membrane) • The thylakoid membrane is folded upon itself forming many disks called grana (singular = granum). • The "cytoplasm" of the chloroplast is called the stroma

  11. Purpose: Convert solar energy to chemical energy

  12. Properties of Light p192 • Light: travels as packets of energy (wavelengths) from? • Sunlight: in as UV, out as IR Optical = Visible, what is seen? • Visible Light Absorb vs Reflect: Black? White? Plants: Absorb (ROYBIV) vs reflect (G) Chlorophyll - #1 Pigment-green, Carotenoids- yellow, orange, red

  13. Chlorophyll Absorbance Spectrum • Pigments: light harvesting molecules on the thylakoid membranes • Each pigment absorbs a different type of light; plant utilizes a much wider range • In green plants, the primary photosynthetic pigments are Chlorophylls a & b. • *Carotenoids: Deciduous trees, Ripe fruit (Oranges, tomatoes, bananas)

  14. Englemann’s Experiment1883 • Aerobic Bacteria- concentrate near an O2 source Alga Control group?

  15. Photosynthesis: Harvesting Light Energy-The Thylakoid Animation (Notes) Stroma: Outside Thylakoid + + + ATP ADP + P1 NADPH + H 4 + NADP+ + 2H+ + 1 1 3 5 2- (P700) 2- (P680) + + + + + + + + Inside the Thylakoid + + + + + PSII, PSI 2. Reaction Centers: Chlorophyl a (Primary Pigment) 3. Proton Pump 4. ATP Synthase (Carrier Protein, enzyme) 5. Electron Carriers- Membrane Proteins

  16. The Light Reactions + + *BOND ENERGY *BOND ENERGY ATP ADP + P1 NADPH + H • Light energy absorbed by all pigments in PSII is funneled down to the reaction center (P680- chlorophyll a); electrons so excited, the pair ‘jump ship’- oxidation occurs as e-’s enter the ETC. “Bucket Brigade” *H2O oxidation • e-’s power the proton pump- move protons from low (stroma) to high concentration (thylakoid lumen); still enough energy to reach PSI > P700; gives up its e-’s to an electron acceptor…..> stroma; attracted to p+ NADPH formed. • Need -ATP synthase: ‘tunnel’ for protons to move from high>low (to stroma), and as an enzyme for ADP > ATP ATP + NADPH “Energy on Hold” for Stage 3 + + + + + + + Chemiosmosis + 1 2 3

  17. Where does the Oxygen come from? enzyme 2H2O 4e- + 4p+ + O2 (1 molecule of Oxygen) ‘Photolysis’: The light splitting of water • Escapes out stroma • Adds to high p+ inside thylakoid • Replaces e- in the ETC- reaction center

  18. Two Possible Routes For Electron Flow in LR:Cyclic vs Noncyclic Flow *Notes, Text p200 Primary Acceptor (Reduction) Primary Acceptor Electron transport chain ETC (Oxidation) Cyclic vs Noncyclic

  19. THE CALVIN CYCLE: STEP 3 Light Independent • ‘CYCLE’ RULES: • Need an acceptor molecule (RuBP- 5C molecule the ‘welcoming committee’) and it needs to be replaced • And rubisco enzyme-catalyzes the reaction-. (6C is unstable; > two 3-C) RUBISCO PGA- an acid *Produced Stage 2 **Need 3 molecules of CO2 to make G3P *On a global scale, photosynthesis makes about 160 billion metric tons of carbohydrate per year. No other chemical process on Earth is more productive or is as important to life. *Produced Stage 2 PGAL/G3P (G3P) Net Gain of 1 G3P(PGAL) Text p203 Notes p6

  20. Chemiosmosis in Mitochondria and Chloroplasts

  21. *PHOTOSYNTHESIS is a REDOX REACTION PHOTOSYNTHESIS vs CELLULAR RESPIRATION *SITE of PHOTOSYNTHESIS > Chloroplasts *SITE of CELLULAR RESPIRATION > Mitochondria*

  22. Photosynthesis 12.27 PHOTOSYNTHESIS

  23. Tissue Systems, Tissues and Cell Types • DERMAL: Epidermis, Periderm ‘derm’ • Protection, Stomata Regulation • VASCULAR: Xylem, Phloem • Conduction, support, storage • GROUND: Parenchyma, Sclerenchyma, Collenchyma ‘chyma’ • photosynthesis (*Parenchyma) • Support (Collenchyma, Sclerenchyma) Text p703 Table 32-1

  24. Anatomy of a Plant Leaf • STOMA- underside of leaf (aka stomate, stomata) • GUARD CELLS • MESOPHYLL LAYER: Photosynthetic cells • VASCULAR TISSUE: • XYLEM: Wider Diameter/Water up • PHLOEM: tubes from leaves to the rest of the plant Mesohyll

  25. PHLOEM VASCULAR SYSTEMS*Not Circulation XYLEM System of tubes and transport cells that circulate water and dissolved minerals (up from roots) Support Dies after one year and then develops new. Rings of a tree • System of tubes that transports sugars and other molecules created by the plant from photosynthesis • Always alive • The dripping sap from a tree usually phloem

  26. PHOTORESPIRATION • The process that reduces the efficiency of photosynthesis in C3 plants during hot spells in summer; requires O2 and produces CO2 and H2O- does NOT produce ATP Evolutionary? (When high CO2 and low O2); GMO’s? • When stomates open, CO2 enters; is available to chloroplasts • When stomates close to conserve water, CO2 exchange is shut off • Chloroplasts still photosynthesizing, leading up to a buildup of O2. • Rubisco enzyme binds to O2 (like it does to CO2) -stops the food making. • Plants go into a dormant-like state.

  27. C3 C4 CAM • Anatomically the same (both have Mesophyll cells to store CO2 • Physiologically different- CAM plants keep their stomates CLOSED during the day, open at night. • Not as efficient, but CAM plants can survive in harsh conditions (Desert) • Corn, Sugarcane, Crabgrass • Stomata open during the day. • Special enzyme for fast uptake of CO2 • Faster photosynthesis than C3 because CO2 then delivered direct to Rubisco- stops photorespiration • Can close stomata sooner/ Fast CO2 uptake • Most Plants • Stomata open during the day. • Photorespiration- slows sugar production (Rubisco grabs O2 not CO2) • More efficient in cool/ moist/low light conditions than C4 or CAM (less machinery, less energy required) • Cacti, Orchids, pineapples • Stomata open at night- less transpiration. • Stores CO2 taken in at night as an acid, breaks it down to CO2 as needed. • “CAM-idle” –Dry spell- close stomata night and day- O2 used for respiration, CO2 for photosynthesis • Recover quicker from dry spells than plants that go dormant (Add to Notes P-13)

  28. ROOT FUNCTIONS • Anchorage • H2O and Mineral Absorption • Food Storage • Tap Roots vs Fibrous Roots Chapter 35 p748

  29. “TACT” Transpiration Adhesion Cohesion Tension

  30. 1. 1. • Water vapor transpires from the surface of leaf mesophyll cells to the drier atmosphere through stomata. • This produces a tension that pulls water out of the leaf xylem toward the mesophyll cells TENSION COHESION MODEL 2. • Cohesive forces (water molecules- H bonds)allow columns of water to be pulled up through the xylem 3. • This in turn pulls water up root xylem, forming continuous column of water from root xylem to stem xylem to leaf xylem. The upward pull of water causes soil water to diffuse into root. Text p741, Figure 34-11 Lab Question #6,7

  31. Water Potentialand Transpiration

  32. Translocation in phloem The pressure flow hypothesis In Phloem. Solutes move from sources to sinks • At source cell (leaf), sucrose is actively moved into phloem sieve tubes (*requires ATP)- reducing their water potential…. • Water diffuses in from xylem, raising the osmotic pressure in the sieve tubes, increases turgor pressure • At sink cell (root),sucrose is actively and passively unloaded into the sink cell (*requires ATP) • Water diffuses back into the xylem Text p743, Lab question #4-5

  33. Factors Affecting Rate of Photosynthesis: Light Intensity: • Light intensity increases, the rate of photosynthesis increases. • At high light intensities the rate becomes constant, even with further increases in light intensity there are no increases in the rate. • The plant is unable to harvest the light at these high intensities; chlorophyll system can be damaged by very intense light levels. • Why different rates? (Which is C3, C4?)

  34. C3 shade plant vs C3 sun plant vs C4?

  35. Factors Affecting Rate of Photosynthesis: • TEMPERATURE: • (a) Increasing rate of photosynthesis as the kinetic energy of reactants increases. • (b) Maximum rate of reaction of photosynthesis at the 'optimal' temperature. • (c) Decrease in rate of photosynthesis as the enzymes become unstable and denature.

  36. Factors Affecting Rate of Photosynthesis: CO2 *Very much like the effect of a substrate on the rate of a reaction. (a) O2 is used up- no photosynthesis; only respiring. (b) Concentration of the CO2 (substrate) increases, rate of reaction increases. (c) The atmospheric levels of CO2 and the associated rate photosynthesis. (d) Maximum rate of photosynthesis. (e) There is a range of values for different plants reaching their saturation level with carbon dioxide. Once the saturation level has been reached- no further increase in the rate of photosynthesis

  37. Text p581… PLANT KINGDOM Vascular • “Tracheophytes” • Conducting Tissue • Xylem (H2O up) • Phloem (food ‘down’) • Enables Larger Size • Ex: Most Plants Non-Vascular* • “Bryophytes” • No Conducting Tissue • Stay Small in Size • Ex- Moss, liverworts Seedless* Seed Producers • Produce Spores • Ex- Ferns Angiosperms Gymnosperms • ALL PLANTS: • Eukaryotic • Autotrophic • Multicellular • Chloroplasts • Cell Walls • Cellulose • Non Flowering “cone-bearing” • “Naked” Seeds (no fruit covering) • Ex- Most Conifers (Evergreens-pines/spruce /fir/hemlock/cedar) • form/function? • Produce Flowers • Seeds (In Fruits) • Most Abundant Dicots Monocots Dicots

  38. Parts of a FlowerANGIOSPERMS “Perfect Flower” = Having both male and female parts STAMEN CARPEL (PISTIL) (+ stigma, style)

  39. POLLINATION The transfer of pollen from an anther (male) to a stigmas (female) of a flower of the SAME species SELF POLLINATION It is important to remember that the transfer of pollen from the male to the female precedes fertilization • Pollination involving the same flower, flowers on the same plant, or two genetically identical plants • A reproductive process in which the pollen from one plant is transferred to the stigma of another plant (*Same species) CROSS POLLINATION Pollen lands everywhere….what stops fertilization errors??

  40. POLLINATORS? PREZYGOTIC BARRIERS? Gametic Recognition

  41. Plant Defenses Adaptions to improve Survival & Reproduction: Mechanical, Chemical *Cuticle- keep water in, pathogens out; close the stomata! Spines! Thorns! *Polymers to reduce digestibility; Odor! *Essential oils- attract predatory insects to kill plant-feeding insects

  42. a) Pathogen-associated molecular patterns (PAMP)- triggers immunity b-c) Pathogens suppress the immune signaling, while some plants have proteins that resist the suppressor, resulting in an immune response

  43. Damage Control – cell death signals Salicylic Acid • Upon infection, salicylic acid forms a concentration gradient with higher levels at the infection site and lower levels outward- infected cells die, distant cells survive.

  44. AUXIN Hormone- Plant Tips- on the ‘dark side’ stimulate the uneven growth • Plant Growth in Response to light/no light

  45. Plants use pigments to respond to environmental conditions- day length. • PLANTS RESPOND TO CHANGES IN DAY LENGTH • *Seasonal flowers

  46. Plant Hormones

  47. PLANT FERTILIZATIONOF FLOWERING PLANTS • ALTERNATION OF GENERATIONS: Dominant independent sporophyte generation; microscopic gametophyte and nutritionally dependent on the sporophyte • DOUBLE FERTILIZATION: Two separate nuclear fusions; unique to flowering plants • HETEROSPOROUS: Two types of spores MEGASPORES: Egg MICROSPORES: Sperm MEGASPOROCYTE: Each young ovule contains a megaspore mother cell produces 4 haploid megaspores (meiosis); one develops into a mature gametophyte- an embryo sac- 7 cells- six with one nuclei, one central cell with two nuclei (polar nuclei). THE MEGASPORE TEXT p610, Fig p612

  48. 7 cells- 6- one nuclei 1 with 2 meiosis Pollen tube leads to one egg; all but 2 disintegrate mitosis

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