aerobic and anaerobic metabolism Flashcards
is oxygen the limiting factor when shifting between aerobic and anaerobic?
- oxygen is the limiting factors when shifting
what is the limiting factor when shifting between aerobic and anaerobic ?
- NAD+ not regenerating quickly enough
- ETC can not keep up the production of ATP > an ^ in NADH : NAD ratio within the mitochondria
where is lactate produced and which enzyme is involved?
- produced from pyruvate
- via lactate dehydrogenase
what does lactate regenerate?
- regenerate NAD+ which is critical to allow resynthesis of ATP
what does accumulation of lactate within cells cause?
- lowers the pH making it more acidic
is lactate the cause of muscle fatigue?
- not the cause of fatigue
- although muscle H+ production ^
what does lactate dehydrogenase consume?
- consumes protons thus restoring NAD+ production
how does lactate leave muscle fibres?
- down a concentration gradient entering less active muscle fibres in turn reforming pyruvate
- this is then reoxidised to yield ATP
what is liver glycogen a source of?
- source of energy during exercise
what is gluconeogenesis?
- during carbon skeletons ; other molecules can be used to synthesise glucose for energy provision
why does lactate enter and where?
- lactate can enter the liver via the blood
- reform pyruvate which is used in gluconeogenesis and shuttle glucose back to the muscle
what is the metabolism of the PCR system?
- 2.6mmol.kg.sec-1
- 0.7 seconds
what is the metabolism of anaerobic carb?
- 1.5mmol.kg.sec-1
- 5- 60 seconds
what is the metabolism of aerobic carb?
- 0.5mmol.kg.sec-1
- > 60 seconds
what is the hydride ion?
H-
- when a substrate is oxidised it gives up 2 H atoms passing 1h- ion to NAD+ forming NADH
- other is released as a proton
describe glycolysis
- anaerobic process occurring in cytosol
- low energy yield> 2ATP but quickly
what does glycolysis form?
- 2 pyruvate and NADH
describe the investment phase
- 2 ATP used to phosphorylase glucose which results in it thermodynamically favouring
what are the net products of glycolysis?
- forms 4 ATP, 2 NADH, 2 high energy triose sugars and 2H+
what do phosphofructokinase and pyruvate kinase?
- enzymes that help the process of glycolysis run smoothly
- regulated through exercise
what does exercise do to glycolysis?
- exercise speeds up glycolysis
- can increase glycolytic rate by 100x
how does exercise speed up glycolysis?(4 factors)
- ^ substrate availability; increased glucogenesis favours glycolysis
- physiological factors; ^ blood flow= ^ glucose flow
- cellular factors; ^ glucose uptake by glucose transporters
- molecular factors; allosteric activation of PK + PFK
what does allosteric mean?
- alteration of the activity of an enzyme by means of a conformational change induced by another enzyme
describe krebs cycle
- aerobic process in matrix of mitochondria
- low energy yield= 44.8 kcal mol-1
what are the net products of krebs cycle?
- ATP, NADH, FADH2
what happens to pyruvate after glycolysis?
- shuttled to the mitochondria and can yield lots of ATP
what happens to pyruvate once its moved to the mitochondria?
- pyruvate is oxidised to form acetyl- CoA via pyruvate dehydrogenase generating NADH
describe the citric acid cycle
- 9 reactions that oxidise acetyl- CoA into carbon dioxide via a series of metabolites that produce NADH + FADH2
what does acetyl- CoA react with to produce?
- acetyl CoA reacts with oxaloacetate
- produces citrate
what can be utilised for a high energy yield?
- 6 NADH and FADH2
how much pyruvate and acetyl CoA is produced from 1 glucose?
- for each 1 glucose produces 2 pyruvates and 2 acetyl- CoA
what happens to the krebs cycle during exercise ?
- upregulated 100x due to changes in key metabolites that modulate key enzymatic steps
what happens to free energy as electrons are transferred?
- free energy decreases as electrons are transferred to FADH and NAD+ during glycolysis and KC
what is used to fuel ATP synthesis?
- NADH and FADH2 via ETC and OP
describe oxidative phosphorylation
- aerobic occurring in mitochondrial intermembrane space and matrix
- high energy yield > 643 kcal.mol-1
what does oxidative phosphorylation produce?
- 26 ATP
- 6 C02
- 6H20
what happens to the hydride ion in the electron transport chain?
- ETC reoxidises reduced coenzymes NADH + FADH2 releasing a hydride ion
- these are passed down a series of haem proteins embedded in the mitochondrial membrane
what do electrons move due to?
- differences in electron affinity
what is recycled back to cytosol and mitochondrial matrix?
- NAD+ and FADH
what is electron flow through each complex coupled to?
- H+ ejection
what is the energy released used for?
- used to pump free protons across the membrane
how many protons are ejected per 2 electrons transfer?
- 10 H+ ejected from the mitochondrial matrix per 2e- transferred from NADH to 02
where is the ATP synthase located?
- embedded in the cristae of the inner mitochondrial membrane
what is ATP synthase directly related to? what is its role?
- supply of ADP and Pi and proton gradient
- ATP synthase bind ADP + Pi when 4 protons are present yielding 1ATP
how many protons and ATPs does 1 NADH produce?
- 10 protons
- 2.5ATP
how many protons and ATPs does 1 FADH produce?
- 6 protons
- 1.5 ATP
what powers the electron transport chain?
- negative change in Gibbs free energy
