photosynthesis Flashcards
what kind of reaction is photosynthesis?
redox
what causes the production of electrons, protons and water?
oxidation of water
what was the great oxidation event?
land was originally anoxic
then bacteria came and used carbon dioxide and light
first cyanobacteria
these created the great oxidation event
oxygen then interacted with methane causing it to drop and live could now develop
what is the carbon cycle?
movement of carbon between land, atmosphere and oceans
why is the carbon cycle important?
plants are primary producers and key sources of energy
everything we eat comes directly or indirectly from plants
where does the carbon cycle happen in plants? photosynthesis
chrloroplasts
within this there is a network of membranes, thylaoids
what happens in the thylakoid membranes?
light dependnt reactions
what happens in the stroma of the chloroplast?
light independent reaction
what is the chloroplast a product of?
endosymbiosis
several ndosymbiotic events lead to this organelle
is endosymbiosis happening today also?
yes
example of endosymbiosis happening today?
green marine slug
spotted salamander
how is the green marine slug an example of endosymbiosis
eats algae
cuts open filament and sucks out chloroplast
transfers chloroplast to own tissue and can now survive for a year without eating
how is the salamander an example of endosymbiosis?
algea is incoprorated into cells and eggs
those without the algae are less sucessful embryos
what did Priestly do/ find?
plants produce good air
candle chamber with mouse in, it died
with now a plant, survived.
plants allow things to survive
what did Ingenhousz do/find?
discovered photosynthesis required light and made oxygen
leaves in a bowl, exposed to light and bubbles form
what did blackman propose about photosyntheis?
happens in two reactions
what did Van Neil show to help with phososyntheisis?
looked at the role of light
took purple suflur bacteria and concluded the process is redox
used radioisotrophic techniques
How did Hill contribute to photosynthesis timeline/
carried out experiments to isolate chloroplasts
what did Ruben and Kamen do?
confirmed everything
used isotopes of carbon dioxide and demonstrated oxygen comes from the water
what role do pigments have in photosynthesis?
asorb the light and at different wavelengths each
what are the pigments in chloroplasts?
chlorphyll A and B
B-carotene
what is chlorophyll A
the primary photosynthetic pigment
what is chlorphyll B
acessorory pigment
what is beta-carotene?
accesory pigment
prevents oxidative damage of chlophyll during photosynthesis
what are the fates of energy durin photosynthesisi?
extra energy converetd to heat and lost
transfered to nearby chlorophyll ( resonance)
electron acceptor
what is a chloryphyll?
green pigment in plants, algae, cyanobacteria
absorbs light powering photsyntesis
role os chlorphyl in light powering
excite electrons located in the porphyin- like ring
shape of chlorphyll?
antenna complex that is associated with a photochemical reactions centre forming a photosynstem
how do the photosysytems work?
light hits the antenna complex
energises electrons
electrons via ressonance pass along chain in redox reaction
high energy electron given to next reciever and oxidises
replacing the missing electron happens with photolysis
water is brokwn down and electron replaced giving the complete cycle
what happens at PS11?
water molecue spit here
anteanna pigments also here
what happens in PPS1?
electron is recieved fro plantacyanin
what is the process of the electron transport hain?
energised electron alows proton from stroma into the lumen
after that the electron goes to cytochrom B6F
goes to planntacyanin, energy lowered
protons in lumen: electrochemical gradient
lysis of water, more protons
protons released by ATP synthase, ATP made
define photophosphylation?
proton gradient driving the ATP synthase to generate ATP
the prtons are phophoylating ADP to ATP
what is a Z-scheme?
energy thermodynamic
what does the Z-scheme describe in photysnthesis?
electron energised and elevated then flows in chain and energy used up
energy levels change and go up ad down
what aid does the couping of PS11 and PS1 do?
boosts electrons to the energy level needed to produce NADPH
what is the cyclic electron flow?
cyclic photophosphylation
generating ATP without making NADPH
only use PS1
electrons not passed to NADP but back to the cycle
who was the pioneer of the calvin cycle?
melvin calvin
what experiments did Melvin calvin and benson do?
used radioactive atoms to follow process in the plant
lollipop experiment
algae photosynthesis and add radioactive oxygen, examined the dead algae for carbon
separated on chromatogram
could see key compounds and sugars that were radioactive
what is the key enzyme
RuBisCo
describe the process of the calvin cycle
1/ carboylation
- 3-phosoglycerine
- unstable and splits into 3 carbon molecule
- ATP and NADPH phosphylation and reduction
- 6 molecules of glyceroldephophate
- one molecule of GP used for sugars
- regeneration of 15C divided by 5 = 3 molecules to ribulose-biphosphate
- cycle can go again now
how many cycles are needed for one 6 carbon sugar>
twice
what is rubisco?
large, slow proteins enzyme
3 olecules of substrate per second
what is the issue with rubsci?
it can bind both carbon dioxide and oxygen
changed depending on environment and affinity
this can be energy wastin
how does rubisco try to prevent using oxygen instead of carbon doxide?
carbon concentrating methods
what is a carbon concenrating mecanhism?
allows carbon dioxide to be fixed and released next to rubisco to it will use this and not see any oxygen
what happens to rubisco if you add one oxygen molecule instead of carbon iodixide to RuBP?
one molecule with three carbon atoms and one molecule with onlt two carbons
why is oxygen in rubusco an issue?
the two carbon molecule created cannoe be used y the calvin cycle to make TP or regenerate RuBP
what is photorespiration?
consumes ATP in an efffort to return to the calvin cycle making GP
it uses peroxisomes and mitochondria
what is a C4 plant?
sugar cane or grasses
what does a c4 plant do?
co2 is taken into cell and converted into bicarbonate. moved to bundle sheath cells via plasmodesmaa and released nearer to rubisco
elegant metho to ensure no carbon idoxide is lost
what is a CAM plant?
stomata i the leaves remain shut during the day to concentrate carbon dioxide and release this near the rubusco
how does a CAM plant wor
CO2 is stored as malic acid in vacuole
at nightstomata open fixing carbon iodixide
mate stored as malic acid in vacuole
during the day stomata close to not waste water
malic accid convereted to pyruvate and carbon is released and used in calvin cycle
how do algae concentrate carbon?
variety of methods
aqutic environment so abundant is bicarbonate
use transporters for bicarbonate
what type of plants do we mainly eat?
c3
what are the three steps of the calvin cycle?
carboxylation
reduction
regeneration
