FA Synthesis

End Product of Fatty Acid Synthesis

  • Main Product: Palmitic acid (C16) is the predominant end product formed during fatty acid synthesis. It is synthesized from the overall reaction of 8 acetyl CoA and 7 malonyl CoA, resulting in the release of 7 CO2, 7 ATP, 14 NADPH, and water.

Storage of Fatty Acids in Adipose Tissue

  • Fatty acids are stored in the form of triacylglycerols (triglycerides).

  • Glycerol 3P is obtained from:

  • Glycerol kinase in the liver and DHAP from glycolysis in adipose tissue.

Increasing Triacylglycerol into Adipose Tissue

  • Factors:

  • Excess caloric intake (especially from carbohydrates) and high insulin levels promote the conversion of excess carbohydrates into triacylglycerol.

Breakdown in Fatty Acid Synthesis

  • Components Required:

  • Acetyl CoA is the primary component that needs to be synthesized to initiate fatty acid synthesis.

Fat Pad Expansion

  • Fat pad expansion occurs due to hypertrophy (enlargement of existing adipocytes) and hyperplasia (increase in the number of adipocytes).

Factors Determining Subcutaneous vs. Visceral Fat Pad Increases

  • Hormonal Influence:

  • Testosterone generally favors subcutaneous fat storage.

  • Estrogen promotes fat storage in the hips and thighs among females.

  • Imbalances can lead to an increase in visceral fat.

Functions of Adipocytes

  1. White Adipocytes (WAT):

  • Unilocular, primarily responsible for lipid storage and release.

  • Main energy reservoir in the body.

  1. Brown Adipocytes:

  • Multilocular, plays a role in thermogenesis (heat production).

  • Activates in response to cold stimuli to burn calories.

  1. Beige Adipocytes:

  • Exhibits characteristics of both white and brown adipocytes.

  • Can convert excess energy into heat through similar mechanisms as brown adipose tissue.

Names of Fatty Acids in Elongation

  • Omega-3 Fatty Acids: e.g., Alpha-linolenic acid (18:3 omega 3) can be elongated to form Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA).

  • Omega-6 Fatty Acids: e.g., Linoleic acid (18:2 omega 6) can be elongated to form Arachidonic acid (20:4 omega 6).

Fatty Acid Elongation Process

  • Function: Source of long-chain fatty acids, except for essential fatty acids (EFA).

  • Substrates: Primarily utilizes palmitate as a starting point.

  • Enzymes: Involves a multi-enzyme complex in the Smooth Endoplasmic Reticulum (SER), using malonyl CoA and NADPH.