TOPIC 5 - respiration Flashcards
name the 4 main stages of aerobic respiration + where they occur?
- glycolysis - cytoplasm
- link reaction - mitochondrial matrix
- Krebs cycle - mitochondrial matrix
- oxidative phosphorylation - via ETC : membrane of cristae
outline stages of glycolysis?
- glucose is phosphorylated to glucose phosphate by 2x ATP
- glucose phosphate splits into 2x triose phosphate (TP)
- 2x TP is oxidised into 2x pyruvate
- net gain of 2x NADH and 2x ATP per glucose
how does pyruvate from glycolysis enter the mitochondria?
via active transport
what happens during the link reaction?
- oxidation of pyruvate to acetate
- pyruvate is decarboxylated = net gain 1x co2
pyruvate is dehydrogenated = net gain 2x H to reduced NAD to NADH - acetate combined with Co enzyme A= acetyl CoA
give summary equation for the link reaction.
pyruvate + NAD + CoA –> acetyl CoA + reduced NAD + Co2
what is produced in the Krebs cycle?
series of redox reactions produces:
1. ATP by substrate level phosphorylation
2. reduced coenzymes
3. Co2 by decarboxylation
outline the stages of Krebs cycle?
- Acetyl CoA (2c) joins (4C) compound = (6C) citrate
CoA is released in this reaction - (6C) citrate is decarboxylated releasing 2Co2
- citrate is also dehydrogenated = releasing H atoms needed to reduce FAD and 3NAD
4.Substrate-linked phosphorylation
A phosphate is transferred from one of the intermediates to ADP, forming 1 ATP
products per cycle =
- 3 x NADH
- 1 x ATP
- 1 x FADH
- 2 x CO2
what is electron transfer chain?
series of carrier proteins embedded in membrane of the cristae of mitochondria
produces ATP through oxidative phosphorylation via chemiosmosis during aerobic respiration
what happens in the electron transfer chain?
electrons released from reduced NAD and FAD
electrons pass along the ETC in a series of redox reactions
energy released is coupled to maintain proton gradient
energy released joins ADP + pi = ATP
oxygen is the final electron accpetor
how is a proton gradient established during chemiosmosis in aerobic respiration?
- energy released from ETC is coupled to the active transport of H+ ions from the mitochondrial matrix to the inter-membrane space
how does chemiosmosis produce ATP during aerobic respiration?
H+ ions move down their conc gradient from the inter membrane space into the mitochondrial matrix via channel proteins and ATP synthase
ATP synthase catalyses ADP + Pi —> ATP
state the role of oxygen in aerobic respiration?
- final electron acceptor in ETC
- produces water as by porduct
what is the benefit of ETC rather than a single reaction?
- releases heat gradually
- less energy is released as heat
name two types of molecules that can be used as alternative respiratory substrates?
protein - amino acids
lipids - triglycerides
how can lipids act as an alternative respiratory substrate?
lipid —-> glycerol + fatty acids
phosphorylation of glycerol –> TP for glycolysis
fatty acid —> acetate for link reaction
H atoms produced for oxidative phosphorylation