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Script

Like all young mammals, human infants depend on milk for nutrition. Milk is rich

in lactose9 a disaccharide made from two sugar molecules. Lactose cannot be directly

absorbed in the small intestine. To digest lactose, mammals produce the enzyme lactase.

the lactose binds to the active site of the lactase enzyme. The enzyme hydrolyzes lactose

and produces two simple sugars, glucose and galactose. These sugars are then absorbed

into the capillaries of the small intestine and redistributed to the rest of the body.

Notes

mammal['mæm(ə)l] 

    n. [C] a warm-blooded vertebrate animal of a class that is distinguished by the possession of hair or fur, females that secrete milk for the nourishment of the young, and (typically) the birth of live young 哺乳动物 

lactose['læktəus] 

    n. [U] a type of sugar present in milk, which is a disaccharide consisting of glucose and fructose units 乳糖 

disaccharide[dai'sækəraid]

    n. any of a class of sugars whose molecules contain two monosaccharide residues 二糖 

intestine[in'testin] 

    n. a long tube in the body between the stomach and the anus 肠 

enzyme['enzaim] 

    n. a substance produced by a living organism which helps a chemical change happen or happen more quickly, without being changed itself 酶 

hydrolyze['haidrəlaiz] 

    vt. to break down (a compound) by chemical reaction with water （使）水解 

glucose['ɡlu:kəus] 

    n. [U] a type of sugar that is found in fruit and is easily changed into energy by the human body 葡萄糖 

galactose [ɡə'læktəus] 

    n. [U] a sugar of the hexose class which is a constituent of lactose and many polysaccharides 半乳糖 

capillary[kə'piləri] 

    n. [C] any of the fine branching blood vessels that form a network between the arterioles and venules 毛细血管