L5 - photosynthesis Flashcards
what is the energy flow of photosynthesis?
light captured by chloroplast, water and carbon dioxide is converted into carbohydrates, oxygen becomes a by-product, the mitochondria breaks down carbohydrates, and chemical energy is released and stored and as ATP
what is the first intermediate of photosynthesis?
a triose sugar (3-carbon)
how many molecules of water is needed to convert three molecules of carbon dioxide into a triose sugar?
6
what is the end produce of photosynthesis?
glucose (6-carbon sugar)
what is anoxygenic photosynthesis?
photosynthesis using hydrogen sulfide instead of stripping electrons off water
in anoxygenic photosynthesis, what is produced instead of oxygen within the cell?
sulfur
how was energy produced before photosynthesis?
all energy on the planet was essentially conserved - the atmosphere was mostly nitrogen
what happened after photosynthesis began?
there was an endless supply of solar energy, oxygen was being produced as a by-product which allowed for the creation of biomass
what organism first began using photosynthesis?
cyanobacteria - capable of splitting water into hydrogen and oxygen
what are the closest relatives of cyanobacteria?
Melainabacteria and Sericytochromatia (cannot photosynthesize)
what is the evolution of photosynthesis?
it had evolved once in Chloroflexus, and was transferred between distant lineage - no common ancestral pathway
how was the ability to photosynthesize in bacteria passed on?
horizontal gene transfer
what is the summary of photosynthesis evolution?
evolution of oxygenic photosynthesis likely happened several times however, origin is probably of one source. HGT spread capability to distant bacterial lineages and cyanobacteria was the precursor to chloroplasts and photosynthesis in plants
plants are ___ autotrophs
photo autotrophs
what are chemotrophs?
obtain energy by oxidation of electron donors in their environments, using Fe2+ as an electron donor and radiant energy to assimilate CO2 into biomass