Module 8 - Photosynthesis

photic zone

zone in the ocean where photosynthesis can occur

whats the overall redox of photosynthesis

CO2 is reduced to form carbohydrate molecules

what are the 2 stages of photosynthesis

light capture and carbon fixation

what is the electron donor of photosynthesis

H2O

what does the oxidation of h2o result in the production of

O2, protons and electrons

where does photosynthesis take place

chloroplast (semi autonomous and self replicating)

what happens during the light dependent reaction overall 

sunlight energy is converted into chemical energy to produce ATP and NADPH

where does the light dependent reaction occur

thylakoid membranes

where does the light independent reaction occur

stroma

what happens during the light independent reaction overall 

ATP and NADPH are used to make carbohydrates

how is light absorbed during the light dependent reaction

PS absorbs light, electron becomes excited, energy is transferred between nearby chlorophylls until reaches the reaction center

antenna chlorophylls

transfer energy in the light dependent reaction, NOT electrons

reaction-center chlorophyll 

transfers electrons to an electron acceptor, must replenish the electron from H2O

what is a photosystem

protein pigment complexes that absorb light

what are the 2 photosystems

psII and psI

how are the so PS connected

electron transport chain

what is the z scheme

energy trajectory in the etc of photosynthesis

what is the flow of electrons and protons in the ETC of photosynthesis 

h2o —> PSII —> cytochrome b6f—> PSI —> NADP+ reductase —> NADPH. drives the protons from stroma to lumen of thylakoid to set up gradient

what is the proton concentration in the ETC of photosynthesis

low in the stroma and high in the lumen

what happens to ATP produced during the light capturing reaction (ETC of photosynthesis)

stays in the chloroplast for carbon fixation

what happens to ATP produced during CR in plants

used for cell growth or anywhere in the cell other than chloroplast

what is the electron carrier from the PSII

plastoquinone, carries electron to cytochrom b6f complex

what is the electron carrier from the cytochrome b6f complex

plastocyanin, carries electrons to PSIby diffusing throuhg thylakoid lumen

calvin cycle. what is is and where does it happen

light independent, happens in the stroma. turns CO2 into a high energy carbon compound

how many steps are in the calvin cycle

15

what are the 3 main stages of the calvin cycle

carboxylation, reduction, regeneration

calvin cycle: carboxylation

CO2 combined with RuBP to form a 6 C molecule, catalyzed by rubisco. the 6C molecule breaks into 2 3C molecules of PGA

calvin cycle: reduction

PGA is phosphorylated by ATP to produce triose phosphates. Triose phosphates then reduced by NADPH. For every 6 triose phosphates made, only 1 is withdrawn from calvin cycle

calvin cycle: regeneration

ATP is used to produce 3 5C RuBP molecules which get used in carboxylation.

why is it important that excess carbs be stored in plants

get used at nigh when there is no sun

what was a major difference between photosynthesis now and then

early photosynthetic bacteria only had 1 photosystem, but it wasn’t enough to capture enough energy

what are the 2 explanations for the evolution of photosynthesis 

horizontal gene transfer or gene duplication and divergence of one of the genes

what was the first organism to use water as the electron donor of photosynthesis

cyanobacteria. believed to have been engulfed by eukaryotic cell to become the chloroplast

fluorescence

re emission of energy in a longer wavelength to reestablish ground state

pigment

molecule containing chromophore, absorbs specific light wavelengths

chlorophyl

major light capturing molecule. absorbs red and blue and reflects green

what are the 2 parts of chlorophyl

porphyrin ring and phytol side chain

what is the structure of the porphyrin ring

Mg in the middle, different side groups result in different types of chlorophyl. it sticks out of the thylakoid membrane 

what is the structure of the phytol side chain

hydrocarbon anchored into the thylakoid membrane

accessory pigments: where are they found

found in thylakoid membrane, such as carotenoids

accessory pigments: what do they do

help absorb light that chlorophyl absorbs poorly, to increase efficiency of light absorption and protect photosynthetic components from damage