Respiration Flashcards
where does link reaction occur in?
mitochondrial matrix
what is the process of link reaction?
- pyruvate enters the mitochondrial matrix by active process via transport protein
- pyruvate will undergo oxidative decarboxylation & oxidative dehydrogenation to form acetyl coenzyme A (acetyl coA).
- it will combine with 2C intermediate compound
- 2 Pyruvate + 2NAD+ -> 2 Acetyl CoA + 2CO2 + 2NADH
what is the process of Krebs cycle?
- acetyl coA (2C) combine with oxaloacetate (4C) to form citrate (6C)
- citrate will undergo dehydrogenation and decarboxylation to form alpha-keto glutamate (5C)
- each decarboxylation step will produce 1CO2
- regeneration of oxaloacetate involves 3 dehydrogenation steps and 1 decarboxylation step
- overall eqn (1 glucose): 2ADP + 6NAD+ 2FADH -> 6NADH + 2ATP + 2FADH2 + 4CO2
where does oxidative phosphorylation occur at?
mitochondrion membrane
what is the process of oxidative phosphorylation?
- In the presence of O2, NADH & FADH2 transfer their high energy electrons to electron carriers of ETC & get oxidized in the process.
- as electrons are passed down electron carriers of increasing electronegativity, energy released is coupled to H+ pumped from matrix to intermembrane space, generating a proton gradient
- H+ protons diffuses through ATP synthase back into matrix, down the gradient by facilitated diffusion.
- ADP is phosphorylated to form ATP via chemiosmosis
- oxidation of NADH & FADH2 allows the regeneration of NAD+ and FAD, allowing them to pick up more electrons from KC, LR & glycolysis -> for these reactions to continue
- O2 act as final e- acceptor at the end of ETC, combining w/ e- and h+ to form H2O
- equation for 1 glucose: 10NADH x 2.5 + 2FADH2 x 1.5 = 28ATP
comparison points of anaerobic respiration in human and yeast [5] (RLPPF)
[similarity]
reason for anaerobic + aerobic:
1. high DD for ATP due higher muscle contractions -> rapid increase in glycolysis -> rapidly deplete (limited) NAD+ -> oxidative phosphorylation is unable to regenerate NAD+ fast enough
2. aim: produce small amount of energy (2ATP) to at least cope w/ cellular processes & to regenerate NAD+ from NADH for glycolysis to continue
[differences]
location:
1. human: muscle cell cytosol
2. yeast: yeast cell cytosol
process:
1. human: pyruvate is reduced by e- from NADH, catalyzed by lactate dehydrogenase to lactate
(2 pyruvate -> 2 lactate + 2ATP)
2. yeast: pyruvate is converted to ethanol & CO2, which is catalyzed by pyruvate decarboxylase -> reduced by e- from NADH to ethanol catalyzed by alcohol dehydrogenase
(2 pyruvate -> ethanal + 2CO2 -> 2 ethanol + 2ATP)
impacts & fate of products:
1. human: lactic acid accumulates in the muscle cell faster than it is being removed -> cause muscle fatigue
lactate will be transported from muscle cells to liver by bloodstream -> convert back to private -> to enter link reaction + krebs cycle -> generate more atp
2. yeast: wine & beer fermentation
final e- acceptor:
1. human: pyruvate
2. yeast: ethanol
what is the process of glycolysis?
P- phosphorylation of glucose
- 2 ATP is invested to undergo phosphorylation and make glucose more reactive and committed to glycolysis
- 2ATP + C6H12O6 -> 2ADP + fructose 1,6-biphosphate
L- lysis
1. phosphorylated glucose lyses to form 2 glyceraldehyde-3-phosphate (G3P)
2. fructose 1,6-biphosphate -> 2G3P
O- oxidation by dehydrogenation
1. 1 G3P will oxidise by dehydrogenation and phosphorylation
2. G3P + Pi + NAD+ -> 1,3 biphosphoglycerate + NADH
S- substrate level phosphorylation
1. dephosphorylate to form ATP & glycerate phosphate
2. glycerate phosphate form pyruvate
3. 1,3 biphosphoglycerate + ADP -> GP+ATP; GP +ADP -> pyruvate + ATP
OVERALL: 1 glucose + 2ATP + 2ADP + 2NAD+ -> 2 pyruvate + 2ATP + 2NADH
Location of Glycolysis?
Location of Link Rxn
Location of Kreb’s Cycle?
Glycolysis: Cytosol
Link Rxn & Kreb’s Cycle: Mitochondrion Matrix (singular)
Describe the Kreb Cycle and its components [4]
Acetyl CoA (2C) formed through link reaction combines with oxaloacetate (4C) to form citrate (6C)
- Citrate is decarboxylated and dehydrogenated to form α-ketoglutarate (5C) & NADH
- Each decarboxylation step results in a loss of carbon as a CO2 molecule
- Regeneration of oxaloacetate (4C) involves 1 decarboxylation step and 3 dehydrogenation steps to
yield 2 NADH, 1 FADH2 1 CO2
What is the final electron acceptor in Ox Phos?
Oxygen
Where does Ox Phos happen?
Mitochondrion membrane
How does Ox Phos generate the proton gradient/p.m.f?
In presence of O2, NADH and FADH2 transfer their high energy electrons to electron carriers of electron
transport chain & get oxidised in the process
- As e- are passed down electron carriers of increasing electronegativity, energy released is coupled to pumping of H+ from matrix into intermembrane space* to generate a proton gradient
Describe the process of Ox Phos [5]
In presence of O2, NADH and FADH2 transfer their high energy electrons to electron carriers of electron
transport chain & get oxidised in the process
- As e- are passed down electron carriers of increasing electronegativity, energy released is coupled to pumping of H+ from matrix into intermembrane space* to generate a proton gradient
- As H+ diffuses through ATP synthase back into matrix* down the gradient by facilitated diffusion,
ADP phosphorylated to form ATP via chemiosmosis - *Oxidation of NADH and FADH2 allows regeneration of NAD+ and FAD, allowing them to pick up more
electrons from Krebs cycle, link reaction & glycolysis, so that these reactions can continue - O2 act as final e- acceptor at end of ETC, combining with e- and H+ to form H2O
When does anaerobic respiration happens?
Exceptionally high DD(ATP) due to higher muscle contractions → rapid increase in glycolysis →
rapidly depletes limited NAD+ as Oxidative Phosphorylation unable to regenerate NAD+ fast
enough
What’s the aim of anaerobic respiration?
Aim: to produce small amount of energy (2ATP) to at least cope with cellular processes & to
regenerate NAD+ from NADH for glycolysis to continue (by having respective final e- acceptor)
