Cellular Respiration

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Cellular Respiration

• Two Phases
• 1. Glycolysis
• Cytoplasm
• Anaerobic
• Sucrose (12C) 4 Pyruvates (3C)
• 4 ATP
• 4 NADH

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Cellular Respiration

• 2. Krebs Cycle
• Mitochondria
• Aerobic
• (Citric Acid or TCA Cycle)
• 4 Pyr ---gt 12 CO2
• 4 ATP
• 16 NADH
• 4 FADH

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Cellular Respiration

• 3. Total (12)
• Sucrose ---gt 12 CO2
• 8 ATP
• 20 NADH 60 ATP
• 4 FADH 8 ATP
• ________________
• 76 ATP for every Sucrose

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Glycolysis

• Sucrose
• 12 C 2 x 6 C
• 2 x 6 C 4 x 3 C
• Pyruvate

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Krebs Cycle

• 4 PYR 12 CO2
• 4 NADH
• 1 FADH
• 4 ATP

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Electron Transport Chain
Intermitochondrial Space
24 H
4H
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Christae
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48 H
24 H
Matrix
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Final Products

• Sucrose
• 12 CO2 TCA from Sucrose
• -12 O2 Cytochrome Oxidase
• 24 H2O Cytochrome Oxidase
• -24 H NADH FADH
• -24 H Cytochrome b/c
• 68 ATP Electron Transport
• 8 ATP TCA Glycolysis
• _____ ____
• 76 ATP
• 8 Cal / ATP
• 608 Cal / mole of Sucrose

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Lecture 8Photoregulation

• Photosynthesis
• Light Quantity
• Photomorphogenesis
• Light Quality
• Photoperiodism
• Light Duration
• Phototropsim
• Light Direction

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Photomorphogenesis

• Light Quality
• Seed Germination
• Release from dormancy
• Weed seeds
• Red Light (5 sec) Induce Germination
• Far-Red (5 sec) Inhibit Germination
• R FR - Inhibit
• R FR R - Induce

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Photomorphogenesis

• Seedling Development
• Etiolated
• Dark
• long, spindly, white (or yellow)
• De-Etiolated
• Light
• Red Light ( 5 sec pulse)
• short, thick, green
• R FR
• etiolated

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Photomorphogenesis

• Internode Elongation
• Shade Adapted (Shade Tolerant)
• No Response
• Shade Avoidance (Shade Sensitive)
• Low Red Far-Red Ratio
• Canopy Shade
• Rapid Elongation
• Escape Shade

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Photoperiodism

• Daylength Perception
• Short-Day Plants
• Dark Period
• Longer than Critical Minimum
• 5 min Night Break
• Red - Inhibits Flowering
• Far-Red Promotes Flowering
• R FR R - No Flowering

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Photoperiodism

• Long-Day Plants
• Dark Period - Less than Critical Maximum
• Night Break - Not very effective
• End-Of-Day Far-Red
• 8 hr day 5 min R - No Flowering
• 8 hr day 5 min FR - Flowering
• 8 hr day FR R - No Flowering
• Daylength Extension
• Low Red Far-Red Ratio
• Like Shade Avoidance
• Promotes Flowering
• Not R/FR reversible

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Phototropism

• Directional Information
• Blue Light
• Stem Bending
• Toward Light
• Lateral Redistribution of Auxin
• Auxin High on Shaded Side
• Increased Growth
• Stomatal Opening
• Blue Light Activation of ATPase
• H ion extrusion
• K/Cl- Uptake
• H2O uptake
• Swelling of Guard Cells

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Phototropism

• Leaf Movements
• Heliotropism - Legumes
• Pulvinus
• Similar to Stomatal Opening
• Multicellular
• H / K, Cl- exchange ---gt H2O uptake ---gt
  Swelling
• Dorsal lt---gt Ventral Motor Cells
• Dorsal swell ---gt Leaf moves up
• Ventral swell ---gt Leaf moves down

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Phytochrome

• Dark Red Dark
• P -------gtPr ----------------gt Pfr ------gt
  Response lt---------------
• Far-Red
• Molecular Switch
• Pfr - Active Form

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Phytochrome Absorption
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Blue Light

• Cryptochrome
• Cry-1, Cry-2
• Bacterial Photolyases
• Hypocotyl Elongation (Cry-1)
• Flowering (Cry-2)
• Phototropin
• Phot-1, Phot-2
• Flavoproteins
• Hypocotyl Bending
• Carotenoid
• Stomatal Opening (?)

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UV Absorbing Pigment

• UV-B (280-320 nm)
• DNA
• Thymidine Dimers
• Chromosome Damage
• Unknown Photoreceptor
• UV-A (320-400 nm)
• Protein
• Photolyase
• DNA Repair
• Phototropin

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Thermal Energy

• Heat
• Motion of Atoms and Molecules
• 0 K No Molecular Motion
• Quantitative Measure
• 1. BTU (British Thermal Unit)
• 1 lb H2O ----gt 1 F
• 2. calorie
• 1 g H2O -----gt 1 C
• 3. Kilocalorie or Calorie
• 1 kg H2O -----gt 1 C

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Energy Transfer

• 1. Conduction
• Through Matter
• Atomic and Molecular Collisions
• eg. Frying Pan
• 2. Convection (Sensible Heat)
• Movement of Molecules through Space
• Brownian Motion of Air
• Carries Heat Energy with it
• Long-Wave IR - 3,0000 - 50,000 nm

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Energy Transfer

• 3. Radiation
• Electromagnetic Absorption
• Short Wave IR - 800 - 3,000 nm
• UV Visible - 300 - 800 nm
• Absorbed energy re-emitted as heat
• Direct Transfer
• Source (Lamp) -----gt Object (Leaf)
• does not heat air between
• leaf T gt air T

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Specific Heat

• Measure of Energy Transfer
• Thermal Energy of Substance
• Specific Heat
• Heat Energy Required to Change Temperature by 1.0
  C
• Liquid H2O 1.0 cal/g (highest)
• Ice (solid) 0.5 cal/g
• Steam (gas) 0.48 cal/g
• Heat of Fusion (Phase Change)
• Solid lt----gt Liquid
• H2O 80 cal/g
• Heat of Vaporization
• Liquid lt----gt Gas
• H2O 540 cal/g

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Cardinal Temperatures

• 1. Optimum
• Maximal Growth Rate
• 2. Maximum
• Tempreature above which growth stops
• 3. Minimum
• Temperature below which growth stops

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Q10

• Change in Rate of Reaction with every 10 C
  change in Temperature
• Logarithmic Scale
• Q10 1.0 - no change
• Q10 2.0 - doubles every 10 C (100)
• Q10 3.0 - triples every 10 C (200)
• Metabolic Reactions
• Respiration Q10 2.0
• Photosynthesis
• Light Reactions Q10 1.0
• Dark Reactions Q10 2.0
• Photorespiration Q10 3.0
• C4 Plants
• higher temperature optimum and maximum
• no photorespiration

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Plant Growth

• 1. Degree Days (Days to Maturity)
• Empiracal - varies between species
• 1. Base Temperature
• Temperature Minimum
• Peas 40 F (4.5C)
• Peaches 48 F (9.0C)
• 2. Mean Temperature
• Establish mean temperature for day
• Subtract Mean T - Base T degree day
• eg. for peas _at_ 50 F (10 C)
• 50 - 40 10 degree days (DD)
• 2,000 DD required for maturity
• additive during growing season

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Dormancy

• Three Types
• a. Eco-Dormancy (imposed dormancy)
• Environmental Conditions
• lt Tmin or gt Tmax
• resume when conditions improve
• b. Para-Dormancy (Physiological Dormancy)
• Endogenous period of rest
• Axillary bud inhibition by terminal apex
• c. Endo-Dormancy (True Dormancy)
• Endogenous Dormancy
• not removed when conditions improve
• specific requirements to overcome
• Light - seed dormancy
• Cold - chilling hours - bud break

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Dormancy Release

• Chilling Requirement
• Hours lt 7 C (45 F)
• Reduction in ABA
• Peaches
• 600 - 1,000 hours
• establish southern limit

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Seed Dormancy

• Dessication
• Increase in ABA
• Release
• Light
• Lettuce, weeds
• even after chilling requirement met
• Stratification
• imbibition - wet peat moss
• 2 - 4 C
• 2 weeks - 2 months
• Increase in GA
• Decrease in ABA

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Other Temperature Responses

• Vernalization
• low temperature requirement for flowering
• Winter annuals
• Biennials
• Tuberization Bulbing
• Short Day Induction
• Potato
• Temperature Optimum 15 - 18 C
• gt 30 C - none formed
• gt 20 C - Inhibited
• lt 15 C - Inhibited
• lt 10 C - none formed

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Heat Stress

• Solar Energy
• 1100 W/m2 Total (Solar Constant)
• 400 W/m2 IR (800-50,000 nm)
• 400 - 500 cal /cm2/day
• 1 cal 1.0 C/ g H2O
• 1 - 10 g H2O / leaf
• Leaf Temperature Increase only 2 - 5 C

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Leaf Cooling

• 1. Reflection - not all absorbed
• light leaf color
• Dusty Miller
• 2. Conduction
• Leaf to stem and root
• 3. Convection
• heating of air around leaf
• wind removal
• 4. Radiation
• reradiation to dark sky at night
• heat dissipation
• 5. Heat of Vaporization
• most important
• evaporative cooling
• 540 cal/g H2O

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Stomatal Regulation

• Increase VPD and Stomates Open
• High Temperature
• Low Relative Humidity
• High Soil Water
• Leaf Temp. 2 - 5 C gt Air Temp.
• 30 C (90F) 5C 35 C (95F)
• Decrease VPD and Stomates Close
• High Temperature
• High Relative Humidity (Still Air)
• Low Soil H2O
• Leaf Temp. 10 - 15C gt Air Temp.
• 30 C 15 C 45 C (113 F)

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Low Temperature Stress

• 1. Chilling Injury
• Tropical Subtropical
• lt 10 C (50 F)
• bananas - browning in refrigerator
• citrus - buds die
• 2. Freezing Injury
• Ice Crystal Formation
• Intracellular ice
• Disrupts cell membranes
• Intercellular ice
• Cell Walls
• Lower Solute than Cytoplasm
• Freeze First
• Water moves out into wall
• Cell Dessicates

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Low Temperature Stress

• Freezing Point Depression
• Increased solute in walls decreases freezing
  point prevents ice formation to ca. - 10 C
• Supercooling
• Water in Xylem
• increased pressure produces a glass
  formation still liquid (glass) at -40C

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Types of Damage

• 1. Winter Dessication (Winter Burn)
• Evergreens (eg. Rhododendron)
• Low RH, Frozen Soil
• Sudden Warm Period
• Increased Transpiration
• No Water Uptake
• 2. Frost Heaving
• Poorly Drained Soils
• Cracks Fill with Water
• Freeze/Thaw
• Expose Roots

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Types of Damage

• 3. Root Injury
• Soil Freezes
• Shallow roots (eg. Strawberry)
• No Root Dormancy
• 4. Bark Splitting
• Apples
• -7 to -10 C
• Rapid Drop in Temp.
• Exposes Cambium
• 5. Southwest Injury
• Trunk exposed to sun
• Increase Temp. during day
• Rapid Temp. drop at night

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Resistance Mechanisms

• 1. Dormancy
• Vegetative Buds - Woody Perennials
• Floral Buds
• Seeds - Annuals
• 2. Herbaceous Habit
• Above Ground Tissue Dies
• Below Ground around 0 C
• 3. Leaf Shedding
• Deciduous Habit

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Resistance Mechanisms

• 4. Hardening
• enhanced by photoperiod
• slow temp. decrease
• Stress
• exposure to one stress confers resistance to
  another
• gradual decrease in
• H2O
• Temperature
• Nutrients (especially Nitrate)
• conversion of starch to sugar
• increase solute concentration
• lower freezing point
• increase in unsaturated fatty acids