Stage 3 and lipids Flashcards
What is the purpose of the tricarboxylic acid cycle?
To completely oxidise glucose, breaking all the carbon-carbon bonds and oxidise carbon atoms to CO2 and use the rest of the hydrogens to reduce NAD+and FAD.
How is the tricarboxylic acid cycle regulated?
Major signals to regulation are the ADP/ATP ratio, and the NAD/NADH ratio. An enzyme involved in an early irreversible step of the tricarboxylic acid cylce is isocitrate dehydrogenase and this is allosterically inhibited by NADH and activated by ADP.
What are the intermediates of the TCA cycle used for?
c5 and c4 intermediates can be used for the synthesis of nonessential amino acids, c6 intermediates can be used for the synthesis of fatty acids and some c4 intermediates can be used to synthesise glycolipids.
What are the two groups that lipids can be placed in?
Fatty acid derivatives (trigylercols ecosinaids, phospholipids) and hydroxy methyl gluarteic acid derivatives
What does the first stage of metabolism for triglycerols constitute?
Hydrolysed by panceratic lipase into glycerol and fatty acids.
How is gylercol metabolised?
This occurs in the liver, where glycerol kinase catalyses the reaction to produce glycerol phosphate (which can be used for fatty acid synthesis), which can then be reduced using NAD for o dihydroxyactectone phosphate.
What are the stages of catabolism of fatty acids?
Fatty acid activation, fatty acid transport to mitochondria, and b-oxidation of fatty acids.
How are fatty acids activated?
By linking with coenzyme A, in a reaction that is catalysed by fatty acid coA synthase.
How are fatty acids transported into the mitochondria?
By using a caratine shuttle.
What is B- oxidation of fatty acids?
A sequence of reactions that oxidises the fatty acid and produces a c2 unit, producing NADH and FaD2H
How are ketone bodies produced?
They are synthesised in the liver mitochondria, by the use of lyase and reductase enzymes in a process that is controlled by the ratio of insulin/glucagon.
What do you need for the formation of ketone bodies?
Fatty acids available from excessive lipolysis which are used to supply the substrates, a low ratio of isulin/glucose in the blood plasma.
What are the required substrates for the tricarboxylic acid cycle?
Acteyl CoA, NAD+, FAD and oxaolactetate.
