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BIOL 1003 Lecture Notes - Light-Dependent Reactions, Active Transport, Photodissociation

3 pages53 viewsFall 2012

Course Code
BIOL 1003
Elizabeth Nisbet

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All chemical reactions in a cell → arranged into metabolic pathways
Intermediates in these pathways are called metabolites
Catabolic reactions (e.g. respiration) release energy
Anabolic reactions (e.g. photosynthesis) use up energy
Leaf Structure
Phototropism → growth towards light
Large leaf surface area → captures more light
Thin leaves → few cell layer → more light captured by chlorophyll
Leaf mosaic increases leaf exposure to light
Internal Structure
o Cuctile → reduces H2O loss by evaporation
o Palisade mesophyll → chloroplast can move around cell for max light absorption
o Spongy mesophyll → allows diffusion of gases through leaves
o Phloem sieve tube → removes products of photosynthesis
Thylakoid membrane: light-dependent → large surface area
o Associated with chlorophyll, accessory pigments, ETC, enzymes
Grana: stacks of thylakoid membranes
o Enclose hydrogen reservoir used in chemiosmosis
Lamella: tubular extensions forming a network between grana
Stroma: RuBP carboxylase catalyses light independent reaction
Starch granule → insoluble storage carbohydrate product of photosynthesis
Light Dependent Reaction
In Thylakoid Membrane / Granum
IMG 5-14-6
Chemiosmosis/Photophosphorylation produces ATP
//H+ from photolysis remain in thylakoid space
ETC releases energy
Used to pump H+ from stroma into thylakoid space
By active transport and electrochemical gradient
H+ conc in thylakoid space > stroma
H+ ions pass back from space between two mitochondrial membranes
Through pores which are associated with the enzyme ATP synthetase
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