Fatty acid synthesis

Definition

Fatty acid synthesis is the biological process by which organisms create fatty acids, essential components of lipids, from acetyl-CoA and malonyl-CoA through a series of enzymatic reactions. This process occurs mainly in the cytoplasm and is crucial for producing energy storage molecules and membrane components, linking it directly to lipid biosynthesis and degradation.

5 Must Know Facts For Your Next Test

1. Fatty acid synthesis primarily occurs in the liver and adipose tissue, where enzymes like fatty acid synthase catalyze the reactions.
2. The process begins with the carboxylation of acetyl-CoA to form malonyl-CoA, which then donates two-carbon units to growing fatty acid chains.
3. NADPH, generated from the pentose phosphate pathway, serves as a reducing agent during fatty acid synthesis.
4. Different organisms can have variations in their fatty acid synthesis pathways; for example, plants often use different enzymes than animals.
5. Fatty acid synthesis is regulated by hormonal signals like insulin, which promotes lipid storage, and glucagon, which encourages lipid mobilization.

Review Questions

• How does acetyl-CoA contribute to fatty acid synthesis, and what role does malonyl-CoA play in this process?
  • Acetyl-CoA acts as the primary substrate for fatty acid synthesis by providing the initial two-carbon unit. Malonyl-CoA is formed from acetyl-CoA through carboxylation and serves as a two-carbon donor during the elongation of the fatty acid chain. Together, these two molecules enable the assembly of long-chain fatty acids through a series of condensation reactions facilitated by fatty acid synthase.
• Discuss the significance of NADPH in fatty acid synthesis and how it is generated within the cell.
  • NADPH is critical for fatty acid synthesis as it provides the necessary reducing power for the reduction steps during chain elongation. It is primarily generated through the pentose phosphate pathway and also from malic enzyme activity, which converts malate into pyruvate while producing NADPH. This highlights the interconnectedness of metabolic pathways in supplying resources for lipid biosynthesis.
• Evaluate how hormonal regulation impacts fatty acid synthesis and its implications on overall metabolic health.
  • Hormonal regulation significantly affects fatty acid synthesis; insulin promotes this process by enhancing glucose uptake and increasing levels of substrates like acetyl-CoA. Conversely, glucagon and epinephrine inhibit fatty acid synthesis when energy needs are high. Understanding these regulatory mechanisms is crucial since imbalances can lead to metabolic disorders such as obesity or diabetes, emphasizing the importance of maintaining proper lipid metabolism for overall health.

Related terms

Acetyl-CoA: A key metabolic intermediate that serves as the starting point for fatty acid synthesis and is produced from the breakdown of carbohydrates, fats, and proteins.

Fatty Acid Desaturation: The biochemical process of introducing double bonds into fatty acid chains, which alters their physical properties and influences membrane fluidity.

Triglycerides: The primary storage form of lipids in animals, consisting of three fatty acids esterified to a glycerol backbone.