respiration Flashcards
(28 cards)
4 stages of aerobic respiration and where in mitochondria?
Glycolosis (cytosol)
Link Reaction (Matrix)
Krebs Cycle (Matrix)
Oxidative phosphorylation (cristae)
aims of glycolysis (3)
partial glucose breakdown
produce 2 ATP per glucose
produce 2 pyruvate, 2 NADH
stages of glycolysis (4)
phosphorylation of glu
lysis
oxidation by dehydrogenation
substrate-level phosphorylation
phosphorylation of glucose
(process, product)
activates glucose by adding a phosphate group from ATP , commits sugar to pathway
catalysed by phosphofructokinase (PFK)
lysis ( process )
6C glucose split into 2 3C sugar phosphate (favoured one is triose phosphate)
oxidation by dehydrogenation
(process + prod)
triose phosphate oxidises by dehydrogenation (NAD takes the H, gets reduced to NADH)
substrate level phosphorylation
(process + prod)
3C dephosphorylated to form pyruvate, 2 phosphate groups go to 2 ADP to form 2 ATP
Link Reaction (3 steps)
each pyruvate is decarboxylated, losing CO2
oxidation by dehydrogenation occurs, giving 2 NADH and a 2C
2C forms with coenzyme a, acetyl coenzyme a (also 2C)
Krebs Cycle
requires oxygen!!
(2C) acetyl + (4C) oxoace = citrate (6C)
oxidative decarboxylation: 6C to 5C, w 1 NADH prod and CO2
5C to 4C (oxidative phosphorylation, substrate level phosphorylation and oxidation), forming 2 NADH, 1 ATP, 1 FADH2, CO2
(ONE CYCLE)
products of 1 glucose in Krebs cycle
2 turns of cycle
2 x (+1ATP +3NADH +1 FADH2 -2CO2)
= 2 ATP, 6 NADH, 2 FADH2, 4 CO2
describe oxidative phosphorylation
process where energy in the form of high-energy electrons in NADH and FADH2 are used to generate ATP in presence of O2
oxidative phosphorylation step 1 - NADH
NADH donates electrons to final electron carrier of electron transport chain, which passes its electrons to the next carrier and so on.
NADH –> NAD+2e+H
oxidative phosphorylation step 2-
pumping
as high energy e are transferred down increasingly electronegative electron carriers in ETC, energy is released.
Energy is used to actively pump H+ (protons) from matrix to intermembrane space via electron carriers
builds up a proton-motive force, or proton gradient, across cristae
oxidative phosphorylation step 3
chemiosmosis
protons diffuse through ATP synthase down the proton gradient from intermembrane to matrix
ATP synthase phosphorylates ADP to ATP in the matrix via chemiosmosis
oxidative phosphorylation step 4 -
final acceptor
oxygen acts as final electron acceptor, combining with H to form H2O
why is proton gradient formed?
charged protons canot pass through hydrophobic core of inner mitochondrial membrane
production of ATP for 1 mol glucose
2 in glycolysis + 2 in Krebs + 34 in ETC via oxidative phosphorylation (first 4 via substrate-level phosphorylation)
production of other compunds
10 NADH and 2 FADH2 (all used in oxidative phosphorylation)
anaerobic respiration features
oxidation of glucose without oxygen, only 2 ATP mlc per glucose
types of anaerobic resp
alcohol and lactic acid fermentation
functions of anaerobic
- produce a small yield of energy
- regnerate NAD from NADH (for glycolysis to continue)
alcohol fermentation
(in yeasts)
after glycolysis
pyruvate (3C) to ethanal (2C) through decarboxylation (release CO2)
ethanal reduced to ethanol by alcohol dehydrogenase, removing H from NADH to form NAD
NADH from glycolysis regenerated
lactic acid fermentation
(in animals)
after glycolysis
pyruvate reduced to lactate by electron from NADH
final electron acceptor in anaerobic
ethanal in yeast, pyruvate in animals
