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1.4 碳水化合物及其代谢1.4.1 糖类物质如何分类?糖的种类很多,按其分子组成可分为如下几类:(1)单糖:单糖是含多羟基的醛类或酮类化合物,是一类不能再水解的最简单的糖类。根据单糖所含的碳原子数目,可将单糖分为丙糖、丁糖、戊糖和庚糖。对每种单糖来说,又有醛糖(含醛基)和酮糖(含酮基)之分。(2)低聚糖:又称寡糖,由几个单糖分子(通常为2个～6个)脱水缩合而成。重要的低聚糖有二糖(麦芽糖、蔗糖、乳糖)、三糖(棉籽糖)、四糖(水苏糖)。(3)多糖:由多个单糖分子脱水缩合而成的高分子化合物,如淀粉、菊糖、糖元、纤维素、半纤维素、右旋糖酐、香菇多糖等。(4)糖的衍生物:包括糖的还原产物、氧化产物、氨基取代
1.4 Carbohydrates and Their Metabolism 1.4.1 How are sugars classified? There are many kinds of sugars, and their molecular composition can be divided into the following categories: (1) Monosaccharides: Monosaccharides are polyhydroxyl-containing aldehydes or ketones. , is a kind of simplest sugar that can’t be hydrolyzed. According to the number of carbon atoms contained in the monosaccharide, monosaccharides can be divided into triose, tetrose, pentose, and heptose. For each monosaccharide, there is also a distinction between aldose (containing aldehyde groups) and ketose (containing ketone groups). (2) Oligosaccharides: Also known as oligosaccharides, dehydrated and condensed by several monosaccharide molecules (usually 2 to 6). Important oligosaccharides are disaccharides (maltose, sucrose, lactose), trisaccharides (raffinose), and tetrasaccharides (stachyose). (3) Polysaccharides: High molecular compounds derived from dehydration condensation of multiple monosaccharide molecules, such as starch, inulin, glycogen, cellulose, hemicellulose, dextran, lentinan, and the like. (4) Derivatives of sugars: including sugar reduction products, oxidation products, amino substitution