3.5 Energy transfers in and between organisms Flashcards
where does the LDR take place
on thylakoid membrane in chloroplast
where does the LIR take place
in stroma in chloroplast
what happens during LDR
- chlorophyll absorbs light energy , excites electrons to higher energy level, releasing electrons from cholorphyll= photoionisation of chlorophyll
- some of energy from electrons released is conserved for ATP and NADPH production
- electrons pass down ETC via redox reactions, losing energy at each step
- energy used to actively transport protins from stroma to thylakoid
- creates electrochemical gradient across thylakoid membrane
- protons move down electrochemical gradient via facilitated diffusion into stroma catalysed by ATP Synthase embedded in thylakoid membrane
- energy from this allows ADP + Pi –> ATP (photophosphorylation)
- chemiosmostic theory
- electrons excited + transfeered to NADP + a proton from photolysis
- forms NADPH
what is photolysis + its role
splitting of water molecule using light energy producing protons, electrons, oxygen H20 --> O + 2H+ + 2e- electrons replace those lost from chlorophyll
products of LDR and what are they used for
ATP –> LIR
NADPH –> LIR
O2—> leaves cell as by product or for respiration
describe the calvin cycle
- carbon dioxide reacts with RuBP to form two molecules of GP
- catalysed by the enzyme rubisco
- ATP + NADPH form LDR used to reduce GP to triose phosphate
- some of the triose phosphate is used to regenerate RuBP in the Calvin cycle
- some of the triose phosphate is converted to useful organic substances.
define limiting factor
- when made a more favourable value, increases rate of photosynthesis
- till photosynthesis limited by another factor
how does temperature limit photosynthesis
- rate increases as temp increases
- limits LIR as enzyme controoled
increase up to optimum
- more KE
- more E-S complexes
above optimum
- H bonds in tertiary structure break
- active site changes shape, enzyme denatures
- fewer E-S complexes
how does light intensity limit photosynthesis
-rate increases as intensity increases
reduced dramatically
- low levels of ATP and NADPH
- LDR limited as less photoionisation + photolysis
- so LIR slows/stops
- GP not reduced to TP as needs ATP + NADPH
- TP cant regenerate RuBP
how does CO2 conc limit photosynthesis
-rate increases as co2 conc increases
conc dramatically reduced
- limits LIR
- less co2 to combine with RuBP to form GP
- less GP reduced to TP
- less TP converted to organic substances + to regenerate RuBp
agricultural practices to overcome effect of limiting factord
artificial light - maximise light intensity
heat in greenhouse - increase temp
burn fuel - release more Co2
where does glycolysis occur
in cytoplasm
draw glycolysis
book
anaerobic respiration of pyruvate
animals
-pyruvate to lactate
plants/yeast
-pyruvate to ethanol
NADH oxidised to NAD
glycolysis can occur again
lower ATP yield
where does the link reaction
matrix of mitochondria
