Oxidative Phosphorylation Flashcards
What is the essence of oxidative phosphorylation
Electron from NADH and FADH(2) are used to reduce oxygen and water
Their energy used to pump hydrogen ions from mito matrix to inter membrane (pH in intermem space decrease whilst matrix increase)
Protons flow back across mem along conc grad
Energy of proton flow is used to phosphorylate ADP to ATP
How does NADH form the cytoplasm get in
During glycolysis 2 NADH are formed in cytoplasm
NADH Cannot cross inner mito mem
Uses the glycerol-3-Phosohate and maleate-aspartate shuttles
Explain the Malate-aspartate shuttle
NADH form glycolysis is used to generate malate form oxaloacetate in cytosol
Malate transporters transfer malate to mito matrix
Malate conv to oxalaacetate gen NADH in mito matrix
What is the phosphoryl transfer potential
Potential of NADH(+) and FADH(2) is converted into this
Can be measured by free energy change for hydrolysis of ATP
How is the electron transfer potential measured
By the redox potential (reduction potential) of a compound
What is the standard redox potential
How readily a substance donates an electron in comparison to hydrogen
A -ve standard redox potential = means sub has lower affinity for electrons than Hydrogen
What is the standard free energy change for ATP
-31.4 KJ/mol
What are the tow steps of oxidative phosphorylation
1- electron transport - electrons flow form NADH and FADH2 to oxygen, energy used to pump hydrogen ions out of matrix
2- ATP synthesis - electrochemical gradient of hydrogen across the mitochondrial inner mem , energy stored in this gradient to synthesise ATP
What has separate Proton pumps
Electron transport and ATP synthesis
Describe the electron transport in the respiratory chain
Four multi subunit complexes in inner mito mem
Electrons form NADH enter at complex 1
Electrons from FADH(2) enter at complex 2 (TCA cycle)
Electrons are passed on via q-cytochrome complex 3
Electrons are transferred to oxygen to form water complex 4
Electrons handed down from higher to lower redox potentials
What are cytochromes
Proteins contain a haem group as functional cofactors
Haem containe iron which takes up and release electrons
What is the hydrogen pump
Mutually the same as electrons
3 of 4 RESP complexes pump hydrogen ions
Is there protons in the intermem space or matrix
More in intermem space as electrochemical grad until electrical field of matrix negative and they want to move back which can be done with the synthesis of ATP
How do protons flow back form the inter membrane space to the matrix
Via atp synthase
What is the ATP synthase
F(1)F(0)ATPase
Conformational change leads to ATP synthesis
Has a proton channel
How can electron transport be inhibited
Cyanide, azide and CO inhibit transfer of electrons to oxygen
No proton gradient can be formed so no ATP can be synthesised
What does UCP stand for and do
Uncoupling protein - thermogenin
Generates heat by shrt circuiting the mitochondrial activity
Causes non shivering thermogenesis
What is 2,4-Dinitrophenol
Artificial uncoupler
Creates a proton leak
Used as an anti obesity drug as increases metabolic activity
Other UCP-3 isoforms are used for obesity therapies
What is UCP-3
Expressed in skeletal muscle involved in thermogenesis
What is the P:O ration
Is measurement of coupling of ATP synthesis to electron transport
Strongly influenced by UCP activity
What is the ATP yield from one glucose molecule
30-32 molecules of ATP
Deep on which shuttle used
From on glucose molecule how many FADH AND NADH
From the TCA PDC and glycolysis
2FADH(2)
10 NADH + 10H(+)
