5.7 respiration Flashcards
first step of respiration
glycolysis
glycolysis stesp simple
glucose -> hexose bisphosphate -> 2x triose phosphate -> 2x pyruvate
how to get from glucose to hexose bisphosphate
PHOSPHORYLATION
- 2 molecules of ATP are hydrolysed to ADP and Pi, the Pis add onto carbon 1 and 6 of glucose
how to get from triose phosphate to pyruvate
- dehydrogenase enzymes (2nad+ -> 2 nadh) remove hydrogens frorm each triose phospahte, and are accepted by the NAD+
- simultaneously, 4ADP + 4Pi = 4ATP
in what conditions is glycolysis carried out under
ANAEROBIC (so happens in both types of resp)
inputs of glycokysis
- glucose
- 2 ATP
outputs of glycolysis
- 2x pyruvate
- 4 x ATP (net of 2)
- 2 NADH
where does glycolysis occur
cytoplasm
cristae
inner membrane of mitochondira; folded
what occurs in the matrix
- link
- krebs
matrix contains. …
- enzymes for link and krebs
- mDNA
- 70s ribosomes
how does pyruvate enter the mitochondria
active tranposrt
purpose of cristae
- large SA for electron carriers
- and ATP synthase
wahts special about intermembrane space
- close to mitochondrial matrix
- so reduced nad and fad can easily dilver h+ to ETC
HOW BIg is outer layer of mitochondria
- envelope
- 2 layers
link reaction steps
- pyruvate is decarboxylated (CO2 released)
- pyruvate is dehydrogenated (nad+ to nadh)
- this forms an acetyl group. combines with coenzyme A (CoA) to form acetyl CoA
steps of krebs
- acetyl CoA drops of the acetyl group (2c) which combines with oxaloacetate (4c) to form citrate(6c)
- citrate DECARBOXYLATED and DEHYDROGENATED NAD to form a 5c compoun
- DECARBOXYLATED and DEHYDROGENATED NAD again, to form a 4c compound
- with this 4c, substrate level phosphorylation, 1 ATP produced , dehydrogenation again WITH FAD, dehydrogenation again WITH NAD
- oxaloacetate regenerated
how many carbons in acetyl group
2
how many carbons in oxaloacetate
4
how many carbons in citrate
6
how many times does krebs happen per glucose
twice, as 2 pyruvates made in glycolysis, so 2 acetyl coas
product of krebs (ONCE)
- 3 NADH
- 1 FADH
- 2 CO2
- 1 ATP
how can fatty acids be respired
broken down to acetate, combine with acetyl coa to enter krebs
how can glycerol be respired
- converted to pyruvate
- link
how can amino acids be respired
- deamination
- enter krebs / become pyruvate/ acetyl coa
order of what happens to the 4 carbon stuff
atp produced
fad reduced
nad reduced
BACK TO OXALOACETATE
STEPS OF OX PHOS
- NADH and FADH are oxidised as they release e- into ETC
- e- move down etc through carriers (series of reduction and oxidation with the fe2+ inside)
- as they do so, they release energy needed to AT pump H+ from matrix into intermembrane space, establishing a proton gradient
- e- recombine w h+ and o (FINAL ELECTRON ACCEPTOR) to form water
-CHEMIOSMOSIS. h+ flow down their gradient FD through ATPase back into the matrix
porotn motive force, synthesis of ATP from ADP + Pi
what is the final electron acceptor in respiration
oxygen
- in ox phos when it combines with the electrons and h+ to form water
how much NET aTP produced in glycolysis
2 (2 used up in the beginning, 4 produced at the end)
how much atp producedin link
0
how much atp produced in krebs
2
how much atp produced in ox phos
28
why is ATP yeild usually lower than 32? (2)
- some ATP needed to AT pyruvate from glyoclisys into mitochondria
- some protons may leak out of envelope
describe what happens if theres no o2 present?
- o2 cant act as final electron acceptor in ox phos. e- after etc and protons after doing ATPase cant combine to form water
- concentration of protons INCREASES in matrix, reducing proton gradient across cristae
- ox phos stops
- nadh and fadh cannot become oxidised, so arent regenrated
- krebs stops and so does link
how do fungi anaerobic
eg yeast
ETHANOL fermentation pathway
how do mammals anaerobic
lactate fermentation pathway
describe ethanol fermentatioin pathway
- glycolysis happens
- each pyruvate is DECARBOXYLATED (by pyruvate decarboxylase) to form ethanal
- ethanal accepts h from NADH, reducing it to ethanol (ethanol dehydrogenase)
- NAD is reoxidised and regenerated, so can accept h from triose phosphate, so glycolysis can continue
describe lactate fermentation pathway
- glycolysis happens
- pyruvate accepts h from nadh , forming lactate (by lactate dehydrogenase)
- nad is reoxidised and regenrated, can now be reduced by acccpeting h from triose phosphate, so glycolysis continues
fate of lactate (2)
CARRIED TO LIVER
1. converted to pyruvate, reenters link and krebs
2. recyled to glucose and glycogen
what happens if lactate builds up
- lowers pH in muscles
- inhibits enzymes in glycolysis and in muscle contraction
how can monosaccharadies be respired
- ISOMERASE enzymes convert to glucose
how are lipids respired
- triglycerides hydrolysed to glycerol and fatty acids
FATTY ACIDS? - +CoA , acetyl groups, enters krebs
- glycerol: pyruvate for link
why do lipids produce lots of ATP?
- fatty acid chains have lots of hydrogen
- good for chemiosmosis
how can proteins be respireD?
- hydrolysis of peptide bond to amino acids
- deamination in liver
- remaining keto acid enters as pyruvate, acetyl coa, one of the krebs cycle compounds
what dictates the energy levels of each compound, adn what does this mean re oxygen
- number of hYDROGENS
- but the more hydrogens, the more OXYGEN is neededm to combine to form water
how to calculate RQ
co2 produced/o2 consumed
carbohydrate RQ
1
fatty acids RQ
0.7
proteins RQ
0.8-0.9
what does it mean if RQ>1?
- anaerobic respiration
- more co2 produced than o2 taken in
what device measures respiration
respirometer
why place the organisms on gauze
so they dont come into contactw/ sodium hydroxide /soda lime and risk damage
what control do you use on the other side
- glas beads of the SAME MASS as the organisms
what does the volume change in the respiormeeter mean
- if all co2 is absorbed by soda lime
- then the only volume change is due to OXYGEN ABSORBED
how does the volume change in respirometer
- co2 released absorbed by soda lime
- o2 taken in, vol of gas in chamber decreases, reduced pressure so liquid moves towards the respiriing tube
how to reset respiormeter
- syringe depressed to inject air into system
- liquid reset, and can also read o2 used in the syrings
considerations when setting up
- apparatus connected with tube open so it can equilibrate with atmosphere
- place in water bath for 10 ins for temperature to equilibrate
- syringe level notes, and near top of scale
- levels of liquid marked
