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Chapter 10 (photosynthesis (The Stroma Reactions (First step in stroma…

- - - - encompasses gramma rays, X-rays, UV light, Infrared light, etc.
      - radiation referred to by quanta/protons or waves
      - types of radiation have different wavelengths
      - short wavelengths have large amounts of energy
      - long wavelengths have relatively little energy
      - light is a small segment of the electromagnetic radiation spectrum
    - - pigment is a distinctive color from absorbtion of wavelengths
      - some pigments absorb light to protect
      - pigments can attract mates, pollinators, or hiding
      - photosynthetic pigments
        
        transfer absorbed light energy
        
        transfers to electrons that enter chemical reactions
      - Chlorophyll A
        
        critical pigment
        
        only absorbs some red and blue light
        
        high energy quanta has too much energy
        
        electrons are activated by visible light
        
        activated means raised to an higher level orbital
        
        electron goes from ground state to excited state
      - the release of a light by a pigment is called fluorescence
  - - - pair pf chlorophylls
      - in photosystem 1 reaction center
      - absorb red light of 700nm
      - energy excites electron of p700
        
        ferredoxin
        
        located in thylakoid membrane
        
        small protein
        
        active site with 2 iron atoms
        
        iron atoms bound to sulfur atoms
  - - - plastocyanin is now oxidized
      - plastocyanin must require lost electron
      - receives new electron from a complex of cytochrome
        
        this is called cytochrome b6/f complex
        
        in turn gets molecule from plastoquinone
        
        plastoquinone gets molecule from Q
        
        Q is a molecule of Quinone
        
        receives electrons from phaeophytin
        
        phaeophytin becomes oxidized as it donates to Q
  - - - more specific name- Chemiosmotic phosphorylation
      - involved in the chloroplast
        
        chloroplasts make thylakoids
        
        thylakoids come from inner membrane
        
        thylakoids can swell, becoming vesicles
        
        all vesicles occur in the same spot
        
        this is called grana
  - - - mediated by enzymes
      - enzymes aren't bound to thylakoid membranes
    - - accepter molecule reacts with CO2
      - product of 6 carbons
      - new molecule immediately breaks apart
      - stable bonding orbitals cant form
        
        orbitals rearrange
        
        2 identical molecules are formed
        
        molecule- 3-phosphoglycerate
      - carboxylation only
    - - electrons and energy added
      - ATP donates a high-energy phosphate group
      - this converts to 1.3-diphosphoglycerate
        
        this is reduced by NADPH
        
        reduced to 3-phosphogyceraldehyde
        
        phosphate comes off this step
        
        carbon is now reduced & reenergized
    - - some 3-phosphoglyceraldehyde gets taken out
        
        used to build anything the plant needs
        
        the rest stays for more reactions
      - PGAL converts to RuBP
      - chloroplast doesn't need to import RuBp
- - - - first theory
        
        allow pigments to enter every reaction
        
        energized pigments are large
        
        pigments move slowly
        
        pigments never cross membranes
        
        pigments are too energetic
        
        energetic pigments are hard to control
      - second theory
        
        allow pigments to make smaller intermediates
        
        less energetic
        
        photosynthetic reactions:ATP
        
        guanosine triphosphate
    - - 3 methods
        
        substrate-level phosphorylation
        
        animals, fungi, and nonchlorophyllous plants
        
        respire high energy compounds
        
        compounds with high energy phosphate groups are made
        
        force phosphate onto ADP making ATP
        
        photophosphorylation
        
        only occurs in chloroplasts in light
        
        based off photosythesis
        
        only occurs in plants with chloroplast
        
        oxidative phosphorylation
        
        last stages of respiration
        
        occurs in distinct sites in cell
  - - - atom does not carry as many electrons as it can
      - oxidation state increases the positive charge
      - oxidized compounds contain a lot of oxygen
      - oxidizing agents take away electrons
    - - electrons added to atom
      - reduction reaction reduce positive atom charges
      - reduced compounds contain hydrogen
      - reducing power
        
        ability to force electrons onto ompounds
      - reducing agents place electrons onto molecules
  - - - small proteins
      - contain a cofactor heme
      - heme holds an iron atom
      - iron carries electrons
      - intrinsic membrane proteins
      - integral part of chloroplasts thylakoid
    - - transport electrons over short distances
      - pick up two electrons
      - bind two protons
      - hydrocarbon tails make them hydrophobic
      - dissolve easily into lipid component
    - - small protein that carries electrons on a metal atom
      - metal atom being copper
      - loosely associated with chloroplast
      - moves short distance along the surface
      - does not travel far
- - - - when things die, they get disorderly
      - entire life is orderly
- - - - light has 3 important properties
        
        1- Quality of sunlight
        
        refers to colors in contains
        
        refers to wavelengths in contains
        
        sunlight is pure white
        
        during sunset/sunrise light passes tangentially
        
        reflects blue light upwards
        
        light at ground level is red
        
        little effect on photosynthesis
        
        2- Quantity of light
        
        light intensity or brightness
        
        affected by several factors
        
        more light available if less clouds
        
        location of plants affects quantity
        
        earths rotation affects it
        
        3- Duration of sunlight
        
        number of hours per day sunlights available
        
        equator- 12 hours of sun yearround
        
        days become longer In summer north &south
        
        summer has longer brighter days
    - - standard- palisade parenchyma top,
        spongy mesophyll bottom
        
        inefficient for conserving water
        
        excellent for absorbing CO2
      - hot dry climate leaves
        
        packed tightly together
        
        no intercellular spaces
        
        surface area retards water evaporation
        
        difficult to dissolve CO2
    - - affects photosynthesis
      - water is lost throught day
      - water is retained during night
      - metabolic adaptations to conserve water
    - - improves working conditions of RuBP carboxylase
      - RuBP should be compartmentalized
      - needs to be in high CO2 concentration
      - Needs low O2 Concentration
      - mechanism by which CO2 is absorbed
    - - second metabolic adaptation
        
        second to C4 metabolism
        
        not nearly as effecive
      - improves conservation of water
      - permits photosynthesis
      - first found in crassulaceae
      - almost identical to C4 plants