Fatty acid synthesis is essentially the reverse of this process.Because the result is a polymer,the process starts with monomers in this case with activated acyl group (most simply,an acetyl unit)and malonyl units (see Figure 22.2).The malonyl unit is condensed with the acetyl unit to form a four-carbon fragment.To produce the required hydrocarbon chain,the carbonyl must be reduced.The fragment is reduced,dehydrated, and reduced again,exactly the opposite ofdegradation, to bring the carbonyl group to the level of a methylene group with the formation of butyryl CoA.Another activated malonyl group condenses with the butyryl unit and the process is repeated until a C16 fatty acid is synthesized
• Fatty acid synthesis is essentially the reverse of this process. Because the result is a polymer, the process starts with monomers in this case with activated acyl group (most simply, an acetyl unit) and malonyl units (see Figure 22.2). The malonyl unit is condensed with the acetyl unit to form a four-carbon fragment. To produce the required hydrocarbon chain, the carbonyl must be reduced. The fragment is reduced, dehydrated, and reduced again, exactly the opposite ofdegradation, to bring the carbonyl group to the level of a methylene group with the formation of butyryl CoA. Another • activated malonyl group condenses with the butyryl unit and the process is repeated until a C16 fatty acid is synthesized
Triacylglycerols Are Highly Concentrated Energy Stores Fatty acids are physiologically important as(1)components of phospholipids and glycolipids,(2)hydrophilic modifiers of proteins,(3)fuel molecules,and (4) hormones and intracellular messengers. They are stored in adipose tissue as triacylglycerols(neutral fat)
Triacylglycerols Are Highly Concentrated Energy Stores • Fatty acids are physiologically important as (1) components of phospholipids and glycolipids, (2) hydrophilic modifiers of proteins, (3) fuel molecules, and (4) hormones and intracellular messengers. They are stored in adipose tissue as triacylglycerols (neutral fat)
一脂类的生理功能 ☆构成细胞膜的必要成分 ☆氧化供能：9克葡萄糖≈1克脂肪？ ☆其他功能： 保持体温 保护，固定内脏 胆固醇是生成胆汁酸，V①3，类固醇激 素的原料
一 脂类的生理功能 ☆构成细胞膜的必要成分 ☆氧化供能： 9克葡萄糖≈1克脂肪？ ☆其他功能： 保持体温 保护，固定内脏 胆固醇是生成胆汁酸，VD3，类固醇激 素的原料
脂肪酸的通式： OH H3C-(CH2)n-C-C-C=O ①
H3C-（CH2）n-C-C-C=O OH - 脂肪酸的通式：
Triglyceride Triacylglycerol