urgent!!~以下三條statement, 如有錯, 請更正

2006-12-14 6:45 pm

a) polysaccharides are water soluble if their component monosaccharides are water solube. Examples can be found in glycogen and glycosaminoglycans.

b) bile salts, steroid hormones and cholesterol have structurally similar steroid nucleus. They can therefore enter cells by diffusion across the cell membrane.

c) triglycerides made up of saturated fatty acids and glycerol are solids at room temperature because f efficient intermolecular hydrogen bonding between the fatty acids and glycerol

回答 (1)

2006-12-14 10:51 pm

✔ 最佳答案

a) actually whether the polysaccharides are water soluble or not, it depends on whether it can form hydrogen bond with water or not. In the case of cellulose, it's monomer is beta-glucose which is soluble in water, but its polyer cellulose, isn't soluble in water, right? Indeed, most monosaccharides are water soluble. So it got not relation on this.

b) well, bile salts isn't steroid. Whether a substance can diffuse across the membrane, depends on its nature. If it's lipid in nature, it can diffuse into it. If it's protein in nature, it's transferred by a carrier protein, etc. So, diffusion across membrane isn't depends on "steroid nucleus", btw, what's that??

c) Saturated fat are solids not only because of its H-bond. But here, it's correct. Coz the melting point is higher.

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