energy Flashcards
what are the steps in respiration
- glycolysis
- link reaction
- Krebs cycle
- oxidative phosphorylation
where does glycolysis occur
cytoplasm
what happens in glycolysis
glucose is phosphorylated making glucose phosphate (requires 2 ATP) which is then hydrolysed to 2 molecules of TP which is then oxidised to 2 molecules of pyruvate This produces 2 reduced NAD and 4ATP
what is the net production of ATP in glycolysis
2
what happens after glycolysis if no oxygen present
pyruvate converted to lactate or ethanol, reduced NAD is oxidised so that glycolysis can continue
where does the link reaction occur
mitochondrial matrix
what happens in link reaction
pyruvate decarboxylated and oxidised forming acetate which combines with coenzyme A forming acetyl coenzyme A
what are the products per glucose molecule in the link reaction
2 AcetylcoA, 2 CO2, 2 reduced NAD
where does the Krebs cycle occur
mitochondrial matrix
where does oxidative phosphorylation take place
cristae
what happens in oxidative phosphorylation
- Reduced NAD and FAD oxidised to produce H atoms which are split into protons and electrons
- electrons passed down electron transport chain by redox reactions
- energy released by electrons used in production of ATP (chemiosmotic theory)
- in matrix at end of etc, oxygen is final electron acceptor
what are the steps in chemiosmosis (respiration)
- energy used by electron carriers to actively transport protons from matrix to inner membrane space
- protons diffuse down electrochemical gradient via ATP synthase back into matrix
- releasing energy to combine ADP with inorganic phosphate to form ATP
why is oxygen needed for production go ATP on Cristae of mitochondrion
The electron transport chain releases energy for most production of ATP so if there’s no oxygen to act as terminal electron acceptor electrons can’t be passed down ETC and the Krebs cycle and link reaction stop in absence of oxygen because NAD and FAD can’t be produced
where does the light dependent reaction occur
thylakoid membrane
where does the light independent reaction occur
stroma
what is photoionisation
chlorophyll absorbs light energy which excites electrons to a higher energy level, releasing them from chlorophyll
how is ATP produced in light dependent reaction
- electrons pass down electron transport chain from PSII to PSI via redox reactions, losing energy at each step
- this energy used to actively transport protons from stroma into thylakoid
- creating an electrochemical gradient across thylakoid membrane
- protons move by facilitated diffusion down electrochemical gradient into stroma via ATP synthase
- energy from this allows ADP+Pi—>ATP
how is reduced NADP produced in light dependent reaction
in PSI electrons are excited and transferred to NADP reducing it
what happens in Calvin cycle
CO2 reacts with RUBP catalysed by enzyme RUBISCO
produced 2 molecules of GP
Gp reduced to TP using products from light dependent reaction (energy from hydrolysis ATP and proton from reduced NADP)
some TP converted tp useful organic molecules
5 TP used to regenerate RUBP (using rest of ATP)
what is a limiting factor
a factor is limiting if when its made a more favourable value the rate of photosynthesis increases
how is temperature a limiting factor of photosynthesis
rate of photosynthesis increases as temp increases then decreases after- limits light independent reaction as its controlled by enzyme rubisco
increase temp us to optimum=more Ek= more E-S complexes
above optimum= H bonds in tertiary structure break= enzyme denatured= fewer E-S complexes
how is light intensity a limiting factor of photosynthesis
if light intensity was dramatically reduced
levels of ATP and reduced NADP would fall because light dependent reaction limited due to less photoionisation of chlorophyll therefore light dependent reaction would eventually stop as requires ATP and reduced NADP
