3.5.2: Respiration Flashcards
What are the 4 stages of aerobic respiration?
1) Glycolysis
2) Link reaction
3) Krebs cycle
4) Oxidative phosphorylation
Where does glycolysis occur?
Cytoplasm
Describe glycolysis
1) Glucose is phosphorylated into glucose phosphate which require the hydrolysis of 2 ATP molecules into 2 ADP to provide two phosphates
2) Glucose phosphate is split into 2 triose phosphate
3) Triose phosphate is oxidised to pyruvate involving the loss of a H which reduces NAD to reduced NAD. ATP is produced directly by substrate level phosphorylation
What are the products of glycolysis?
2 x pyruvate
2 x ATP
2 x NADH
Where does the link reaction happen?
Mitochondrial matrix
Where does the Krebs cycle happen?
Mitochondrial matrix
Describe the link reaction
1) Pyruvate and NADH are actively transported to the mitochondrial matrix
2) Pyruvate is oxidised to acetate and the H removed reduces NAD to form NADH
3) Acetate combines with coenzyme A to produce acetylcoenzyme A.
4) A molecule of CO2 is lost
What is formed in the link reaction?
2 x Acetyl Co A
2 x CO2 released
2 NADH
Describe Krebs cycle
1) Acetyl Co A rects with 4 carbon molecule to form 6 carbon molecule, coenzyme A is released
2) 6 carbon molecules is converted to a 4 carbon molecule through the loss of CO2 and a series of redox reactions where NAD is reduced to NADH and FAD is reduced to FADH and ATP is generated by substrate-level phosphorylation
What does the Krebs cycle produce?
2 x CO2
1 X ATP
3 X NADH
1 X FADH
Describe oxidative phosphorylation
1) The NADH and FADH are oxidises losing H. H -> H+ + e-. Electrons pass down electron transport chain in the mitochondrial membrane through a series of redox reactions. Electrons lose energy which is used to pump H+ through inner mitochondrial membrane to intermembrane space
2) H+ moves down proton gradient by facilitated diffusion across inner membrane to matrix by ATP synthase which provides energy to form ATP
3) Electrons and H+ combine with oxygen to form water. Oxygen is the final electron acceptor. Without oxygen removing H+ and electrons there would be a back up of electrons and respiration would stop
Where does anaerobic respiration take place?
Cytoplasm
Describe anaerobic respiration in animals
Pyruvate reduced into lactate by gaining H from NADH. This oxidises NAD so it can be reused in glycolysis so more ATP is produced
Describe anaerobic respiration in plants and microbes
Pyruvate reduced into carbon dioxide and ethanol by gaining H from NADH. This oxidises NAD so it can be reused in glycolysis so more ATP is produced
