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Energy Metabolism (Environmental and internal factors (Light (quantity of…
Energy Metabolism
Environmental and internal factors
Light
quality of sunlight
colors or wavelengths it contains
quantity of light
intensity
closer to equator = more intense
photosynthesis is slower on dull days and faster on sunny day
if too intense the plant can develop protection
wax and plant hairs
duration of sunlight
Leaf structure
inefficient for conserving water
good for absorbing co2
cylindrical leaves
water
greatly effects photosynthesis
water is lost because stomata stays open
lets in co2
ratio on water use
C4 metabolism
RuBP carboxylase
occasionally binds to oxygen
photorespiration
energy wasting process
PEP
crassulacean acid metabolisms
second metabolic adaption
hot dry climates
more survival than increased growth
c3 will not live
arid
c4 won't survive
acid metabolism not efficient
present in cactus family
thick cuticle
Photosynthesis
Light dependent reactions
350nm to 760nm
absorption spectrum-graph which shows which wavelengths are most strongly absorbed by a pigment.
action spectrum-shows which wavelengths are most effective at powering a photochemical spectrum.
Chlorophyll a only absorbs some red and some blue light
essential photosynthetic pigment
ground state to excited state
release of light by a pigment is--- fluorescence
accessory pigments-molecules that absorb wavelength
most common accessory pigments in land plants - chlorophyll b and carotenoids
resonance
antenna complex- 300 chlorophylls, carotenoids and their proteins
energy is transferred to a reaction center
photosynthetic unit- pigments and carriers work together in a granule.
if photosynthetic unit is low on chlorophyll b --> photosystem I
if chlorophyll is equal to b it is photosystem II
Photosystem I
pair of chlorophylls - P700
ferredoxin-active site has two iron atoms bound to
Ferredoxin NADP reductase
Photosystem II
like Photosystem I backwards
eventually gets to electron transport chain
NADP---> NADPH
synthesis of ATP
chemiosmotic phosphorylation
moves protons from lumen to storm
electrons flow from water to NADPH its called noncyclic electron
use energy to pump protons into the lumen-->cyclic electron transport
may be original power system
stroma reactions
CO2 to carbohydrate happens here
anabolic metabolim
storage forms of energy and carbon
storage
short term storage
intermediate term storage
Long term storage
anabolic synthesis of glucose is gluconeogensis
carbon dioxide is converted to carbohydrates
Energy and Reducing Power
other electron carriers
cytochromes
contain cofactor heme
heme holds iron atom, and iron atom carries electrons and cycles them between +2 and +3 oxidation states
plastoquinones
transport electrons over short distances
pick up two electrons, bind two protons
hydrophobic
plastocyanin
copper carries electrons
copper picks up electron and reduces to +1
doesn't travel far
reducing power
oxidized means that the atom doesn't carry as many electrons as it could.
compounds in environment are in oxidized state.
"reduced"= electrons added
most organisms are in reduced state.
plants need reducing power because they take in water and CO2
oxidized compounds hold a lot of oxygen, whereas reduced compounds hold a lot of hydrogen.
NAD and NADP are oxidizing agents
NADPH and NADH are strong reducing agents
Energy carriers
energy enters world through photosynthesis
most frequent electron carrier is guanosine triphosphate
three ways that ADP can be converted to ATP
phototphosphorylation
involves light energy in photosynthesis
occurs in chloroplast in light
substrate level phosphorylation
forces phosphate onto ADP making ATP
occurs in all parts of plant all the time
oxidative phosphorylation
ADP is phosphorylated into ATP
phototrophs
gather energy directly from light
heterotrophs
take organic molecules and respire them