electron transport chain Flashcards
what happens in the final stage of respiration
reduced NAD or FAD from glycolysis and the krebs cycle is used with oxygen to make ATP in process called oxidative phosphorylation
what does oxidative phosphorylation involve
an electron transport chain
what is an electron transport chain
series of electron carrier molecules down which electron from reduced NAD or FAD are passed
what also happens the same time as the electron chain transport
the hydrogen ions protons left behind are used in chemiosmosis to supply the energy to synthesise ATP
thinking of the electron transport chain as being at different energy levels
-the first member of the chain is the highest level with steps down
-each electron is passed down from one energy level to another driving production of ATP
what is ATP production know as
oxidative phosphorylation because ADP is phosphorylated in process that depends on presence of oxygen
first hydrogen acceptor in electron transport chain
coenzymes NAD and FAD
-act as hydrogen acceptors for hydrogen released in krebs cycle
-one molecule of ATP produced when FAD is reduced and accepts hydrogen from NADH which becomes oxidised
second hydrogen acceptor
oxygen
-when oxygen is reduced water if formed and the chain is at its end
what are cytochromes
protein pigments with iron group like heamoglobin
what are cytochromes involved in
in electron transport and are reduced by electrons from reduced FAD and reduced NAD which is oxidised again
- molecule of ATP is produced at this stage
what is cytochrome oxidase
-enzyme that receives electrons from cytochromes and is reduced as cytochromes are oxidised
-molecule of ATP also produced at this stage
hydrogen entering from reduced NAD
each molecule of hydrogen passing along electron transport chain from reduced NAD enough energy released to make 3 molecules of ATP
hydrogen entering from reduced FAD
-when hydrogen enters chain from reduced FAD only 2 molecules of ATP reduced
where do link reaction and krebs cycle take place
matrix of the mitochondria
where do the electron transport chain and ATP production take place
the inner membrane of the mitochondria
site of ATPase enzymes
-closely packed stalked particles
what did Peter Mitchell describe
the link between electrons that are passed down the electron transport chain and the production of ATP
what does the chemiosmotic theory explain
explains what happens to the hydrogen ions that are left behind when electrons are passed along the electron transport chain and how the movement of hydrogen ions is coupled to the actual production of ATP
what does Mitchell propose
that hydrogen ions are actively transported into the space between the inner and outer mitochondrial membranes using the energy provides as the electrons pass along the transport chain
what does active transport of hydrogen ions across inner membrane result in
a different hydrogen ion concentration on each side of the membrane
consequences of having a concentration gradient of hydrogen ions across membranes
the membrane space has a higher concentration of hydrogen ions that the matrix so there is a concentration gradient across the membrane
-also pH gradient
-because positive ions concentrated in membrane space there is electrochemical gradient
consequences of various hydrogen concentration across membranes
mean there is tendency for hydrogen ions to move back into the matrix
whats the only way hydrogen ions can move back into the matrix
-through special pores found on stalked particles and have ATPase enzymes associated with them
what happens as hydrogen ions move across different concentration gradients
-as they move along electrical, concentration and pH gradients their energy is used to drive synthesis of ATP
1960 accepted model of formation of ATP
was that a high energy phosphate group was directly transferred to ADP from another intermediate- like end of glycolysis when pyruvate formed
-but intermediate not found and chemiosmotic theory accepted
evolution of cellular respiration
-evolved to produce energy in form of ATP for use in cells
-fact that same process in almost all living organisms means it evolved at early stages of development of organisms and very effective
how much ATP is gained during its oxidation of one molecule of glucose
-38 molecules but 2 molecules used to transport reduced NAD molecules produced by glycolysis through mitochondrial membrane leaving 36 for body cells
how much ATP molecules does oxidation of 2 molecules of reduced NAD provide energy for
process makes about 5 molecules of ATP
how much ATP does oxidation of 2 molecules of reduced FAD make
3 molecules of ATP
overall yield of ATP in aerobic respiration
31 molecules
