5.2.2 Respiration Flashcards
cellular respiration
the breakdown of glucose molecules to produce ATP
ways to make ATP
phosphorylation - cyclic or non-cyclic
substrate level phosphorylation
oxidative phosphorylation
cyclic/non-cyclic phosphorylation
produces ATP to convert GP to TP and TP to RuBP in the Calvin Cycle
substrate level phosphorylation
occurs in glycolysis/ Krebs cycle
purpose of ATP is to allow movement of respiratory intermediates around cell
oxidative phosphorylation
occurs in mitochondria
oxygen acts as final e- acceptor
large number of ATP produced due to chemiosmosis
uses of ATP in a plant
H+ pumps in companion cells - active loading of sucrose
GP to TP, TP to RuBP
active transport of minerals into root hair cells
pumping of ions in/out of guard cells
NA+/K+ pump
protein synthesis, DNA replication, mitosis
chemiosmosis
flow of protons down their electrochemical gradient, across a cell membrane through a channel associated with ATP synthase, resulting in the formation of ATP
where do the high-energy electrons come from in respiration?
reduced NAD
reduced FAD
where is the location of the electron transport chain
inner mitochondrial membrane
folded inner membrane
increase surface area for ATP synthase
four stages of aerobic respiration
glycolysis
link reaction
krebs cycle
oxidative phosphorylation
glycolysis
occurs in cytoplasm
splits glucose
forms 2 molecules of pyruvate
substrate-level phosphorylation
phosphate group is removed from a phosphorylated compound and added to a molecule of ADP to form ATP
occurs in glycolysis & Krebs cycle
the link reaction
oxidative decarboxylation
occurs in mitochondrial matirx
produces acetyl coenzyme A from pyruvate
produces CO2, reduced NAD
uses coenzyme A
how do pyruvate and reduced NAD from glycolysis reach the link reaction?
“mitochondrial shunt mechanism”
active transport of pyruvate and NADH from cytoplasm into matrix
req. ATP
Krebs cycle
coenzyme A carries acetyl group to cycle and is then recycled to link reaction
oxidative phosphorylation
reduced NAD (& FAD)= dehydrogenated @ complex 1 (2)
H atoms split = H+ and e-
e- move into e- transport chain
as e- lose energy, H+ actively pumped across inner mito. memb. into intermemb. space (high proton concentration)
protons flow by chemiosmosis and proton motive force through ATP synthase - ATP produced
oxygen acts as final e- acceptor
theoretical yield of ATP in aerobic respiration
36
why is the theoretical yield not always achieved
H+ ions leak through outer membrane into the cytoplasm - reduced steepness of H+ gradient = less chemiosmosis, less ATP produced
ATP is used to actively transport pyruvate & NADH from cytoplasm into mitochondria
when do eukaryotes respire anaerobically?
when there is not enough oxygen to act as the final electron acceptor
only glycolysis and fermentation occur
if oxygen is absent:
protons moving through ATP synthase by chemiosmosis cannot be accepted by oxygen
proton conc increases in mitochondrial matrix
no H+ gradient, no chemiosmosis, oxidative phosphorylation stops
accumulation of reduced NAD/FAD - cannot be oxidised
Krebs cycle stops
link reaction stops - no NAD/FAD to accept hydrogen atoms
ethanol fermentation
occurs in plants and fungi
2 step process: ethanAL as the intermediate
ethanAL is reduced to ethanOL by NADH
allows NAD to return to glycolysis & accept H atoms in the conversion of TP to pyruvate
lactate fermentation
occurs in animals
lactic acid is produced when pyruvate is reduced
NADH donates H atoms to pyruvate
NAD returns to glycolysis
cell can keep producing net 2 ATP molecules per glucose
respiratory substrates
molecules other than glucose can be used as respiratory substrates
