topic 6 - phototrophic metabolism - general Flashcards
what happens during the redox reaction of photosynthesis
polar covalent bonds in the reactants are broken
non polar covalent bonds in the products are formed
bonding e- between the C and O in CO2 have moved closer to the C atoms
bonding e- between the O and H in H2O have moved farther away from the O atoms
what is biomass
all the matter that makes up an organism after all the water has been removed
in plants
- biomass comes from CO2 (autotroph)
what are the parts of the chloroplast
triple membrane (outer, inner, and thylakoid)
spaces (stroma - calvin cycle, and thylakoid lumen)
what happens on the thylakoid membrane
light absorption be chlorophylls and carotenoids
e- transport
ATP synthesis by ATP synthase
what are the 2 parts of the photosynthetic process
light reactions - transform solar energy into chemical energy
calvin cycle - uses chemical energy to fix CO2 into carbs
- dark/light independent reaction
what is used and produced in the light reactions
use
- NADP+, ADP, Pi, sunlight, and water
produce
- ATP, NADPH (reduced e- carrier) and O2
what is used and produced in the light independent reactions
uses
- CO2, ATP, NADPH
produces
- fixes the CO2 and uses energy to build carbs
what is the association between energy and wavelength of light
energy is inversely proportional to wavelength
shorter wave = more energy
visible light = 400-700nm
400 = blue
700 = red
what are the three things that can happen when a photon strikes an object
reflected
transmitted - pass through
absorb the photon - absorbed by e- that gain the energy of the photon
what are pigments
molecules efficient in absorbing photons
chemical structure allows their e- to readily absorb their energy
how do pigments work
wavelength must exactly match teh energy needed to raise and e- to a higher energy level
if the energy doesn’t match exactly, nothing happens to the e-
what are the 3 things that can happen when a photon is absorbed by an e- that moves from a low energy level to a higher energy level
- e- returns to ground state by emitting a less energetic photon (fluorescence) o releasing energy as heat
- e- returns to ground state as its energy is transferred to an e- in a neighbouring pigment
- high energy e- is transferred to another molecule (e- acceptor)
where are photosynthetic pigments
embedded in thylakoid membrane
what is chlorophyll
main pigment in most photoautotrophs
reflect green
absorb red and blue
what are carotenoids
act as accessory pigments
reflect yellow, red, and orange
absorb blue and green
what is the reason behind leaves changing colour in fall
cessation of chlorophyll production which revelas the colours of other pigments
how are pigments organised
organised into complexes with proteins (photosystems - light harvesting complexes)
what is inside of a photosystem
hundereds of antenna pigments grouped around a reaction centre (collection of proteins that interact with pigments)
when excited, the antenna pigemnts channel energy (energy moves NOT e-) to the reaction centre
what is inductive resonance
energy transfer form one e- to another
what is oxygenic photosynthesis
occurs in prokaryotes
all metabolism occurs in the cytosol and on the cell membrane
cyanobacteria have a photosynthetic mechanism very similar to chloroplasts
responsible for oxygenation of earth
what is anoxygenic photosynthesis
does not produce O2
only known to occur in prokaryotic cells
why does anoxygenic photosynthesis exist
evolved at a time before O2 was present in the atmosphere and organic molecules much less abundant
does NOT oxidise water
likely the first metabolism utilising an ETC
how does anoxygenic photosynthesis work
only use cyclic e- flow to generate PMF
does not produce O2
purple and green sulphur bacteria use H2S as a source of e- instead of water
- produces sulphur
cyanobacteria can also go through cycling e- flow
what are the inputs and outputs of anoxygenic photosynthesis
input
- light, H2S, ADP, Pi, NADP+
output
- sulphur, ATP, NADPH
what is the difference between aerobic cell resp and photosynthesis
photosynthesis = anabolic process (building up carbs)
cell resp = catabolic process (breaking down C based molecules - oxidising and releasign as CO2)
ATP synthase embedded in both
both have ETC that generates PMF
