Lecture 26- ATP production & oxidative phosphorylation Flashcards
What is metabolism?
Living systems acquire & use free energy in order to carry out their functions
2 divides of metabolism
Catabolic
Anabolic
Catabolic metabolism
The degradation of nutrients to salvage components & gain energy
Anabolic metabolism
The synthesis of biomolecules for simpler components
Autotrophs
Synthesis all cellular components from simple molecules
Photoautotrophs
Use light to produce carbohydrates which are oxidised giving free energy
Chemolithotrophs
Obtain free energy from compound oxidation
Heterotrophs
Oxidise carbohydrates, lipids and proteins
Classification of oxidising agents
Obligate aerobes- require O₂
Anaerobes- use sulphate or nitrate
Vitamins
Organic molecules obtained from diet
Water soluble (coenzyme precursors)
Fat soluble (required in diet eg. vitamin C)
Degradative pathways
Often converge on common intermediates
Further metabolised in central oxidadative pathway
Biosynthetic pathways
Carry out the opposite
Few metabolites are the starting points
Metabolic roles of liver (learn overview)
Metabolism of carbohydrate, lipid, amino acids
Metabolic roles of muscle (learn overview)
ATP production for muscle contraction
use glycogen, glucose, fatty acids an ketone bodies as fuel
Metabolic roles of brain (learn overview)
Nerve transmission (high ATP requirement)
Use glucose and ketone bodies as fuels not fatty acids
Metabolic roles of adipose (learn overview)
Fat synthesis & storage
-ve ΔG= ….
ΔG=0 = ….
+ve ΔG= …
-ve ΔG= favourable
ΔG=0 = equilibrium
+ve ΔG= unfavourable- usually require input of ATP
Forms of cellular energy curency
Thioester bond-containing compounds
Reduced coenzymes
ATP
NAD+ accepts … electron(s) and … proton(s)
2 (donated to ETC)
1
FAD+ accepts … electron(s) and … proton(s)
2 (donated to ETC)
2
ATP as an energy carrier
Biological importance depends on the free energy change that accompanies cleavage of phosphoanhydride bonds
Standard free energy of hydrolysis is -7.3 kcal/mol
Reactions with large +ve ΔG are possible by coupling with 2nd process with large -ve ΔG
Substrate level phosphorylation
Direct addition of phosphate group to ADP to form ATP
Oxidative phosphorylation
Energy-rich molecules are metabolised by oxidative reactions
Metabolic intermediates donate electrons to NAD+ & FAD to form NADH + H+ and FADH₂
As e- passes down ETC, they lose free energy- used to pump H+ across inner mitochondrial membrane -> H+ gradient which drives ATP synthesis from ADP + Pi
ETC loaction
Inner mitochondrial membrane
impermeable so requires specialised transport systems
Highly convoluted crisae increase surface area
Mitochondrial matrix contains enzymes responsible for oxidation