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Fatty acid synthesis

Q: What are the differences between fatty acid synthesis and degradation?

S ynthesis takes place in cytoplasma intermediates linked to the SH group of acyl carrier protein (ACP) requires NADPH is used in anabolic reaction, like reductive biosynthesis The growing fatty acid chain is extended by succesive addition of C2 units derived from acetyl CoA. The activated C2 donor is malonyl CoA Degradation takes place in mitochondrial matrix intermediates linked to the SH group of CoA Requires NADH and FADH2 NADH is generated in catabolic reaction, like breakdown

Q: Explain the initiation and elongation process before a fatty acid can be synthesised

Initiation: formation of malonyl CoA Acetyl CoA carboxylase has biotin is as a cofactor. The activated Co2 group is transferred to acetyl CoA resulting in the formation of malonyl CoA irreversible reaction (energy lost as hear) is the rate limiting step of fatty acid synthesis Elongation enzyme system which catalyzes the synthesis of fatty acids is fatty acid synthase complex the extension phase of the fatty acid synthesis starts with the formation of acetyl-ACP and malonyl-ACP Acetyl transacylase Malonyl transacylase

Q: Why does fatty acid synthesis require the activation of the pentose phosphate pathway?

Glucose 6-phospphate to 2 NADPH and Ribulos 5-phosphate Synthesis of fatty acids is a anabolic reaction which needs energy to build with NADPH

5 important questions on Fatty acid synthesis

What is fatty acid synthesis?

Fatty acid synthesis is the reverse of fatty acid degradation. The synthesis pathway: condensation, reduction, dehydrate, reduction

What are the differences between fatty acid synthesis and degradation?

Synthesis

takes place in cytoplasma
intermediates linked to the SH group of acyl carrier protein (ACP)
requires NADPH

is used in anabolic reaction, like reductive biosynthesis

The growing fatty acid chain is extended by succesive addition of C2 units derived from acetyl CoA. The activated C2 donor is malonyl CoA

Degradation

takes place in mitochondrial matrix
intermediates linked to the SH group of CoA
Requires NADH and FADH2

NADH is generated in catabolic reaction, like breakdown

Explain the initiation and elongation process before a fatty acid can be synthesised

Initiation: formation of malonyl CoA

Acetyl CoA carboxylase has biotin is as a cofactor. The activated Co2 group is transferred to acetyl CoA resulting in the formation of malonyl CoA
irreversible reaction (energy lost as hear) is the rate limiting step of fatty acid synthesis

Elongation

enzyme system which catalyzes the synthesis of fatty acids is fatty acid synthase complex
the extension phase of the fatty acid synthesis starts with the formation of acetyl-ACP and malonyl-ACP

Acetyl transacylase
Malonyl transacylase

Why does fatty acid synthesis require the activation of the pentose phosphate pathway?

Glucose 6-phospphate to 2 NADPH and Ribulos 5-phosphate
Synthesis of fatty acids is a anabolic reaction which needs energy to build with NADPH

What is the disease of fatty acid synthesis?

MCAD deficiency (medium chain aceyl-CoA dehydrogenase)

accumulation of medium chain CoA esters
Free CoA drops → acetyl CoA cannot be synthesised anymore (TAC cycle will not work, acetyl CoA activate pyruvate carboxylase). You can also not make ketone bodies with acetyl CoA
Acetyl CoA is needed in fasted state and when your sick because of vomiting the glucose cannot be kept in you system