Respiration Flashcards
respiration
metabolic reactions and processes that takes place in cells of organisms storing energy as ATP (some heat energy released too)
aerobic respiration
requires oxygen, produces large amount of ATP
aerobic respiration equation
glucose + oxygen –> CO2 + water + heat energy
anaerobic respiration
absence of oxygen, produces small amount of ATP
3 types of phosphorylation
oxidative phosphorylation - inner membranes of mitochondria in aerobic respiration, energy for ATP from oxidation-reduction reactions, release in transfer of electrons along ETC
photophosphorylation - thylakoid membranes of chloroplasts in light-dependent stage of photosynthesis, energy for ATP from light, released in transfer of electrons along ETC
substrate-level phosphorylation - phosphate groups transferred from donor molecules(Glycolysis)/enough energy released for ADP to Pi (Krebs Cycle)
stages of aerobic respiration
glycolysis - cytoplasm, generates pyruvate,ATP,reduced NAD
Link reaction - matrix, pyruvate converted yo coenzyme A, generates CO2,reduced NAD,reduced FAD,
Krebs Cycle - matrix, generates CO2,reduced NAD,reduced FAD,ATP, water fed into cycle at 3 reaction points
ETC - cristae of inner membrane, generates ATP,
Glycolysis
no O2 needed
cytoplasm
glucose phosphorylated by 2ATP making reactive, polar hexose phosphate
hexose phosphate splits into 2 triose phosphates
2 triose phosphates dehydrogenate, oxidizing to become pyruvate, hydrogen to NAD to make reduced NAD, energy for phosphate from triose phosphate to convert ADP to ATP by substrate-level phosphorylation, pyruvate produced
glycolysis equation
glucose + 2NAD + 2ADP + Pi –> 2pyruvate + 2reducedNAD + 2ATP + heat energy
link reaction
matrix
pyruvate diffuses from cytoplasm into matrix
dehydrogenated, H released and accepted by NAD forming reduced NAD
decarboxylated, CO2 released, 2acetate group combines with coenzyme A making acetyl coenzyme A
link reaction equation
pyruvate + NAD + coenzyme A –> acetyl coenzyme A + reduced NAD + CO2
Krebs Cycle
matrix
acetyl coenzyme A enters Krebs as an acetate fragment combines with 4C acid forming a 6C compound, coenzyme A regenerated
5C acid dehydrogenated making reduced NAD and reduced FAD, decarboxylated to make CO2 and regenerate 4C acid which combines with acetyl coenzyme A to repeat cycle
electron transport chain
cristae
protein carriers/pumps catalyse reactions that release energy carried by ATP
H atoms carried into ETC by coenzymes NAD and FAD, NAD feeds electrons and protons into ETC at an earlier stage than FAD so synthesis 3ATP whilst FAD synthesis 2ATP
reduced NAD donates electrons of H atoms to electron carriers in ETC providing energy for first proton pump to pump H atoms into intermembrane space (gradient set up, flows through channels through ATP synthetase), electrons power the 3 proton pumps
electrons + protons + oxygen (‘final electron acceptor) make water
similarities of ETC in mitochondria + chloroplasts
high energy electrons
chain of electron carriers
H+ pumps in a membrane + accumulate in high concentration in enclosed compartment
H+ through electrochemical gradient through ATP synthetase
differences of ETC in mitochondria + chloroplasts
oxygen accepts electrons in mitochondria, NADP in chloroplasts
H+ accumulate in inter-membrane space in mitochondria, grana in chloroplasts
chemiosmosis theory
hypothetical total ATP made in aerobic respiration
38
why 38 ATP never quite reached
leakage of protons
cost of ATP to move pyruvate and ADP across membranes into matrix
(heat loss)
anaerobic respiration stages
Glycolysis
no oxygen as final electron acceptor in ETC
pyruvate converted after glycolysis
anaerobic respiration in animals
glycolysis
hydrogen from reduced NAD given to pyruvate which regenerates/reoxidises NAD for glycolysis to continue
pyruvate accepts hydrogen from reduced NAD, reduced, forms lactate
anaerobic respiration in yeast
glycolysis
hydrogen from reduced NAD given to ethanal, regenerates/reoxidises NAD allowing glycolysis to continue
ethanal accepts hydrogen from reduced NAD, reduced, forms ethanol
how many ATP produced in anaerobic respiration
2ATPs per molecule of glucose broken down
lipid as an alternative substrate to glucose
lipids hydrolysed into glycerol
phosphorylated with ATP becoming glycerate-3-phosphate
dehydrogenated by NAD becomes 3C triose phosphate which enters glycolysis pathway
fatty acids split into 2C fragments that enter Krebs as acetyl coenzyme A, hydrogen released + picked up by NAD and fed into ETC
proteins as an alternative substrate to glucose
protein hydrolysed into amino acids, deanimayed in liver (converted to ureas + excreted), residue converted into acetyl conzyme A, pyruvate or some other Krebs cycle intermediate and oxidised
