?lactose

lactose 發(fā)音

英：[?l?kt??s]　　美：['l?ktos]

英：　　美：

lactose 中文意思翻譯

lactose 短語(yǔ)詞組

1、lactose-litmus bouillon ─── [醫] 石蕊乳糖肉湯

2、lactose tests ─── [醫] 乳糖試驗(檢腎機能)

3、lactose litmus culture-medium ─── [醫] 乳糖石蕊培養基(瓊脂,肉湯,明膠)

4、lactose intolerance ─── 乳糖不耐受[癥]

5、lactose litmus agar ─── [醫] 乳糖石蕊瓊脂

6、lactose permease ─── 乳糖滲透酶

7、lactose plasmid ─── 乳糖質(zhì)粒

8、lactose broth ─── 乳糖肉湯

9、lactose killing ─── 乳糖殺死

10、lactose-hydrolysed milk ─── 乳糖水解牛奶

11、Wurtz lactose litmus agar ─── [醫] 活爾茨氏乳糖石蕊瓊脂

12、beta-lactose ─── [醫] β-乳糖

13、beta lactose ─── [醫] β-乳糖

14、Wurtz's lactose litmus gelatin ─── [醫] 維爾茨氏乳糖石蕊明膠

15、lactose-polylysine ─── 乳糖-聚賴(lài)氨酸

16、lactose factor ─── [醫]乳糖因子（乳糖分解酶因子），乳糖因子

17、lactose operon ─── [醫]乳糖操縱子

18、lactose litmus gelatin ─── [醫] 乳糖石蕊明膠(培養基)

19、lactose bile culture-medium ─── [醫] 乳糖膽汁培養基

lactose 相似詞語(yǔ)短語(yǔ)

1、lacunose ─── adj.多孔的；多空隙的

2、lacrosse ─── n.長(cháng)曲棍球；網(wǎng)棒球；袋棍球；n.（Lacrosse）（法）拉克羅斯（人名）

3、acetose ─── adj.醋一樣酸的；制造醋的；醋酸的

4、lactone ─── n.[有化]內酯

5、lactases ─── n.乳糖分解酵素；乳糖酶

6、lactonise ─── vt.內酯化

7、galactose ─── n.[有化]半乳糖

8、lactones ─── n.[有化]內酯（lactone的復數形式）

9、lactase ─── n.乳糖分解酵素；乳糖酶

lactose 常見(jiàn)例句（雙語(yǔ)使用場(chǎng)景）

1、Lactose gives glucose and galactose. ─── 乳糖產(chǎn)生葡萄糖和半乳糖。

2、Congenital lactose intolerance is very rare and is an inherited metabolic disorder rather than an allergy. ─── 先天性的乳糖不耐受是非常罕見(jiàn)的遺傳性的代謝紊亂，而并非過(guò)敏。

3、Disaccharide: Any of a class of carbohydrates, including lactose and sucrose, that yield two monosaccharides upon hydrolysis. ─── 雙糖:碳水化合物的一種,包括乳糖和蔗糖,在水解下可生成兩個(gè)單糖。

4、Lactose Lactose, the milk sugar, is a disaccharide of glucose and galactose and is found only in the milk of mammals. ─── 乳糖是葡萄糖和半乳糖構成的雙糖化合物,它只存在于哺乳動(dòng)物的乳中。

5、The paper introduces the mechanisms that lactic acid bacteria can ferment lactose into lactic acid during manufacture and storage of yogurt. ─── 介紹了酸奶發(fā)酵過(guò)程中，乳酸菌代謝乳糖的機理，及發(fā)生的各種生理生化反應。

6、Studies on the low lactose nutrition milk tablets ─── 低乳糖營(yíng)養奶片的研制

7、Lactose free: Breaks down sugar molecules to ease digestion. Not reduced-calorie or low-fat. ─── 含乳糖：分解糖分子有助消化。低熱量、低脂肪。

8、Milk,especially fermented milk, has many kinds of flavor substances, which includes non-volatile acid, volatile acid, carbonyl compounds and hydrolyzates of protein, fat, and lactose. ─── 乳尤其是發(fā)酵乳中的風(fēng)味物質(zhì)種類(lèi)繁多,包括非揮發(fā)性酸、揮發(fā)酸、羰基化合物以及蛋白、脂肪和乳糖等的分解物。

9、Lactose is a white crystalline substance obtained from whey and used in infant foods,bakery products,confections,and pharmaceuticals as a diluent and excipient. ─── 乳糖是一種從乳清中提煉出的白色結晶物質(zhì)，用作嬰兒食物、面類(lèi)制品、糖果和藥的稀釋劑和賦形劑。

10、The sugar-removing milk has the features of low lactose content and low total sugar content, and is suitable for patient of lactose intolerance and diabetics. ─── 具有低乳糖、低總糖的特點(diǎn)，適宜于乳糖不耐癥和糖尿病患者使用。

11、A monosaccharide, CH2OH(CHOH)4CHO, commonly occurring in lactose and in certain pectins, gums, and mucilages. ─── 半乳糖一種單糖，CH2OH（CHOH）4CHO，一般產(chǎn)生于乳糖及特定的果酸、樹(shù)膠及膠質(zhì)物中

12、For example, the cultural adoptions of agriculture and dairying have, in humans, caused genetic selection for the traits to digest starch and lactose, respectively. ─── 例如，農業(yè)和制酪業(yè)的文化采納，曾經(jīng)在人類(lèi)中分別造成了消化淀粉或乳糖的遺傳性狀選擇。

13、Non alergant ingredients meens NO gluten, lactos, eggwhite, nuts or gmo. ─── 不含過(guò)敏物質(zhì)意味著(zhù)沒(méi)有谷膠、乳糖、蛋白、堅果或味精。

14、Lactose intolerance can be diagnosed with a breath or blood test that can assess how the body reacts to lactose. ─── 乳糖不耐癥可以通過(guò)呼吸或血液測試，測試機體對乳糖的反應。

15、Bile Salt Lactose Fermentation Medium ─── 乳糖膽鹽發(fā)酵液培養基

16、Lactose intolerance stems from a deficiency of the enzyme lactase, which is needed to help digest lactose, a sugar in milk. ─── 乳糖不耐癥的病因是缺乏乳糖酶，這些乳糖酶是消化乳糖的必需物質(zhì)，牛奶中的糖就屬于此類(lèi)。

17、As its proportion and content stability in milk,lactose is suitable to cooperate the milk heat damage research analysis. ─── 乳糖由于其在牛奶中含量的穩定性和所占比重,適合作牛奶熱損傷研究分析。

18、Use scope: May use in the production, the upscale water-soluble medicine, definitely may substitute anhydrous glucose and lactose! ─── 使用范圍:可用于生產(chǎn)中、高檔水溶性藥物,完全可替代無(wú)水葡萄糖和乳糖!

19、Imedeen Classic does not contain lactose, gluten, added sugar or gelatine. ─── 伊美婷產(chǎn)品的添加劑是什么？

20、Lacto vegetarians eat only plant foods and dairy products. They do not eat eggs or meat. Eggs are considered potential animals. ─── 2乳素食者只吃一些植物食品和乳制品。他們不吃蛋和肉。他們認為蛋是一種潛在動(dòng)物。

21、Bifidobacteria are nonmotile. anaerobic. and ferment lactose and other sugars to acetic and lactic acids. ─── 雙歧桿菌元運動(dòng)性.厭氧桿菌.能發(fā)酵乳糖和其它糖產(chǎn)生醋酸和乳酸.

22、Galactose A sugar found in lactose and many polysaccharides. It is an aldohexose, isomeric with glucose. See also sugar. ─── 半乳糖:是存在于乳糖和多糖中的一種六醛糖,為葡萄糖的同分異構體。參見(jiàn)。

23、Humans are mammals, nurse their young and produce an intestinal enzyme that breaks lactose into the simpler sugars glucose and galactose. ─── 人類(lèi)是哺乳動(dòng)物，會(huì )哺育幼兒，而且小腸會(huì )產(chǎn)生酵素來(lái)將乳糖分解成較簡(jiǎn)單的葡萄糖和半乳糖。

24、Crisp and crunchy with a subtle salty flavor! No wheat, gluten, milk, lactose, egg, rice and potato. ─── 不含小麥,牛奶,乳糖,雞蛋等成份,減低過(guò)敏機會(huì )

25、So, what happens if your child has a milk allergy, is lactose intolerant, or simply doesnt like to drink milk? ─── 因此，要是你的孩子對牛奶過(guò)敏，或者有乳糖不耐癥，抑或僅僅不喜歡喝牛奶，那該怎么辦？

26、Contrast to the inhibition of feeding Co2+ at the beginning of the cultivation, adding Co2+ after inducing 2.5h with 1.0% lactose could overcome inhibition on the growth and increase the enzyme activity. ─── 培養起始加入Co2+會(huì )抑制菌的生長(cháng)及酶活,而在1.0%乳糖誘導2.5h后加入則可解除生長(cháng)抑制并促進(jìn)酶活。

27、The positive rate of lactase deficiency test was highest on the second hour when 25g or 12.5g lactose was given, and the difference was significant. ─── 分別攝入乳糖量25克、12.5克,乳糖酶缺乏檢出率均在二小時(shí)后最高,差異顯著(zhù);

28、The Han Chinese, with a few notable exceptions, avoided eating dairy foods altogether: many were, and still are, lactose-intolerant. ─── 除了少數特立獨行的人，普通漢族人從不食用任何乳制品，即使到現在還有許多人還不能吃乳糖。

29、A so-called milk allergy or lactose intolerance is really an intolerance or allergy to pasteurization. ─── 一種稱(chēng)為牛奶過(guò)敏癥或乳糖不耐受癥其實(shí)是對高溫消毒后的牛奶的不耐受癥或過(guò)敏癥。

30、The maximum yield of GOS was 31.2% in a stirred reactor with lactose concentration at 60%. It remained about 88% after 96h (8 batches) reaction. ─── 在CSTR反應器中水解 60%乳糖 ,GOS最大得率為31 2% ,經(jīng)過(guò) 96h( 8批反應 ) ,產(chǎn)物得率為原來(lái)的 88%。

31、How much lactose for piglet diets? ─── 乳糖在仔豬料中的最佳水平?

32、Lactose is the main carbohydrate occurring in milk. ─── 乳糖是乳的主要碳水化合物。

33、Bifidobacteria are thought to help maintain the normal intestinal balance, while improving lactose tolerance; to possess antitumorigenic activity; and to reduce serum cholesterol levels. ─── 雙歧桿菌可以幫助維持正常的腸道平衡,改善人體的乳糖耐受性,具有抗腫瘤生成活力,而且可以降低血漿中的膽固醇含量。

34、bovine lacto transfer technique optimizer ─── BLOTTO

35、Bifidobacteria are nonmotile, anaerobic, and ferment lactose and other sugars to acetic and lactic acids. ─── 雙歧桿菌元運動(dòng)性,厭氧桿菌,能發(fā)酵乳糖和其它糖產(chǎn)生醋酸和乳酸。

36、Yogurtene : yoghurt powder, rich in lactose, which nourishes, repairs and adds volume to hair. Leaves hair wonderfully shiny and healthy again. ─── 乳酪粉：乳酪制成的粉末，富含乳糖，能滋潤、修護及使秀發(fā)濃密?；貜烷W亮健康的發(fā)質(zhì)。

37、Studies on the low lactose yoghurt ─── 低乳糖酸奶的研制

38、Half of the world's population have lactose intolerance, a higher proportion of Asians. ─── 世界人口的一半有乳糖不耐癥，亞洲人中的比例更高。

39、Lactose is a naturally occurring sugar found in milk. ─── 乳糖是牛奶中的天然糖分。

40、Similar hype surrounds lactose intolerance, despite studies showing that highly lactose-intolerant people can safely consume as much as one glass of milk daily. ─── 圍繞乳糖的不耐受性也有同樣的宣傳，雖然研究表明高度乳糖不耐受的人能安全地每日喝一杯牛奶。

41、Low lactose milk physics,chemistry,the lactase method, etc. that analyzed the prevention and cure lactose intolerance produce the craft merit and shortcoming. ─── 分析了防治乳糖不耐受的低乳糖奶物理、化學(xué)和酶法等生產(chǎn)工藝的優(yōu)缺點(diǎn)。

42、But some principles and some experimental phenomenons need to be paid attention to during the course of lactose fermentation,separate cultivation and confirmatory test. ─── 但是在乳糖發(fā)酵、分離培養和證實(shí)試驗過(guò)程中,有些原理及實(shí)驗現象需要引起注意。

43、Lactose is the main chemical compound in dairy product,which plays an improtant role in people's growth. ─── 乳糖是乳制品中的主要化合物,對人體生長(cháng)發(fā)育具有重要作用,但它在人體中需經(jīng)乳糖酶水解,才能被消化吸收。

44、An enzyme occurring in certain yeasts and in the intestinal juices of mammals that is capable of splitting lactose into glucose and galactose. ─── 乳糖酶一種能將乳糖分解成葡萄糖和半乳糖的酶，它存在于某些酵母或哺乳動(dòng)物的體液中

45、The Paper mainly studies on hydrolyzing of lactose in milk at the low temperature. ─── 主要探討了鮮牛乳中乳糖的低溫水解。

46、ACV content was determined by ultraviolet-visible spectrophotomery at 254nm(E=622). Lactose content was determinedby enthronlsulphuric acid method using a lactose standard. ─── 偶聯(lián)物中乳糖含量的測定用硫酸-蒽酮法，阿昔洛韋的含量測定用紫外分光光度法，測定254nm的吸光度，根據吸收系數（E~(1%)=622）換算成ACV的濃度及含量。

47、Lacto Ovo vegetarians eat plant foods, eggs, and other dairy products. ─── 1奶蛋素食主義者吃一些植物食品、雞蛋和乳制品。

48、Not only because of lower milk antidiarrheal drug efficacy, the lactose containing ingredients also easy to add to diarrhea. ─── 因為牛奶不僅降低止瀉藥藥效，其含有的乳糖成分還容易加重腹瀉癥狀。

49、One kind of microbe might be able to feed on, say, lactose, whereas the other could not. ─── 如果要區分兩種桿狀細菌，微生物學(xué)家就要做代謝的實(shí)驗，譬如其中一種能以乳糖維生，而另一種不行。

50、For example, lactose intolerance, where people don't have the digestive enzymes to fully digest sugar in milk products, can cause bloating, cramping or diarrhea. ─── 例如，乳糖不耐受的患者因不具有能完全消化乳制品中糖的消化酶，會(huì )在服用乳制品后出現腹脹、腹痛或腹瀉等癥狀。

51、Reduce lactose to if you have lactose to not be able to bear or endure,take quantity disease, when you eat dairy produce, the possibility arises bilge morale problem. ─── 減少乳糖取量假如你有乳糖不耐癥，當你吃乳制品時(shí)，可能產(chǎn)生脹氣問(wèn)題。

52、Disaccharide: Any of a class of carbohydrates, including lactose and sucrose, that yield two monosaccharides upon hydrolysis. ─── 雙糖：碳水化合物的一種，包括乳糖和蔗糖，在水解下可生成兩個(gè)單糖。

53、We will strive to become an export-oriented enterprise gearing to the Southeast Asia and international market with international treading as treading lacto and high-tech as the engine. ─── 公司一直面向東南亞及國際市場(chǎng)，以國際貿易為主導，以高新技術(shù)為發(fā)展動(dòng)力的外向型企業(yè)。

54、They are mainly used to measure the concentration of various liquids of cane sugar, glucose, lactose, maltose, etc. In sugar house, breweries. Yeast factories and alchol factories. ─── 主要用于制糖廠(chǎng)、啤酒廠(chǎng)、酵母廠(chǎng)、酒精廠(chǎng)、以測定各種蔗糖、葡萄糖、乳糖、麥芽糖等溶液的濃度。

55、Commercially available lactose digestive aids can aid in the digestion of dairy products. ─── 商業(yè)廣告中推薦的乳糖消化助劑能夠幫助消化乳制品。

56、About 70% of the people in the world are suffering the malnutrition caused by lactose malabsorption which is resulted by lactose deficiency and lactose intolerance. ─── 可通過(guò)直接口服乳糖酶或在乳制品中加入乳糖酶對乳品加以處理而得到改善。

57、Lactitol (I) was synthesized from lactose by catalytic hydrogenation. In order to be more suitable to the industrialized production, its technological conditions have been optimized and improved. ─── 以乳糖為起始原料經(jīng)催化氫化制得拉克替醇，對工藝條件進(jìn)行優(yōu)化、改進(jìn)，使之更適合于工業(yè)化生產(chǎn)。

58、Any of a class of carbohydrates, including lactose and sucrose, that yield two monosaccharides upon hydrolysis. ─── 雙糖碳水化合物的一種，包括乳糖和蔗糖，在水解下可生成兩個(gè)單糖

59、Moreoer, in case of lactose intolerance (any carbohydrate malabsorption for that matter).The fecal pH is Iow and reducing substances are present on Clinitest examination. ─── 在另一方面，滲透性腹瀉中，糞便液中電解質(zhì)總的含量遠低于糞便液的滲透壓。

60、The calibration models of moisture, protein, fat, lactose, and sucrose for CHCMP are established with MLR. ─── 使用多元線(xiàn)性回歸法分別建立了近紅外檢測的兒童高鈣奶粉水分、蛋白、脂肪、乳糖和蔗糖的快速測定模型。

61、Lacto vegetarians. Avoid red meat, fish, poultry, and eggs. Choose milk, milk products, and plant-based foods. ─── 乳蛋奶素食者。避免紅肉，魚(yú)和家禽。選擇雞蛋，牛奶和植物類(lèi)食物。

62、The most important properties of lactose can be summarized as follows. (i) It is a reducing sugar and can therefore participate in the Maillard reaction when milk is heated. ─── 乳糖主要性質(zhì)總結如下：（1）乳糖是還原糖,因此加熱乳,會(huì )參與美拉得反應。

63、The milk crude protein and SCC had significant difference (P0.05) between the experiment and contrast groups. ─── 乳蛋白率和體細胞數與對照間差異顯著(zhù)(P0.05)。

64、The most important representatives of disaccharides are sucrose (from beet or cane), lactose, maltose and cellobiose. ─── 二糖最重要的代表是蔗糖（來(lái)自于甜菜或甘蔗），乳糖，麥芽糖和纖維二糖。

65、Lactose intolerance is nothing to be embarrassed about. I'm a fancy indian man. ─── 不能吃乳糖不是什么丟臉的事。我是夢(mèng)幻印度情人。

66、Solids-not-fat therefore includes the protein, lactose, minerals, vitamins and minor nitrogenous compounds in milk. ─── 因此非脂乳固體包括：蛋白質(zhì)、乳糖、礦物質(zhì)、維生素和少量的非蛋白氮族化合物。

67、It also introduced several new products and highlighted the technology innovation including colostrum, low lactose milkpowder, fruit cereal milkpower, ect. ─── 同時(shí)對幾種高科技產(chǎn)品--初乳粉、低乳糖奶粉、蘋(píng)果橘子乳米粉等做了重點(diǎn)介紹。

68、Irritable bowel syndrome: is the search for lactose intolerance justified? ─── 乳糖不耐受的研究是正確的嗎?

69、Lactase: An enzyme occurring in certain yeasts and in the intestinal juices of mammals that is capable of splitting lactose into glucose and galactose. ─── 乳糖酶:一種能將乳糖分解成葡萄糖和半乳糖的酶,它存在于某些酵母或哺乳動(dòng)物的體液中。

70、In addition, the enzyme possessed transgalactosylation activity. Galacto oligosaccharides, both tri and tetrasaccharide, were involved in the products during lactose hydrolysis. ─── 另外,該酶具有轉半乳糖苷的活力,在水解乳糖過(guò)程中,生成包括三、四糖的半乳糖低聚糖。

71、People who are lactose intolerant or have a milk allergy. ─── 有乳糖不耐癥和牛奶過(guò)敏的人。

72、Camel milk contains five times more vitamin C than cow milk, less fat, less lactose and more insulin, making it a good option for diabetics and the lactose intolerant , Van Almsick said. ─── 凡?阿爾姆西克說(shuō)，駱駝奶所含的維生素C是牛奶的五倍，低脂肪、低乳糖和高胰島素，因此很適合那些糖尿病患者和乳糖不耐癥患者飲用。

73、But this is crazy when most Asians are lactose intolerant. ─── 但是由于亞洲人無(wú)法接受乳糖，這件事就變得很瘋狂。

74、Comparing with heat pasteurization, the losses of protein, lactose and deoxidized vitamin C were less, the color was not s... ─── 與熱殺菌相比,脈沖磁場(chǎng)殺菌時(shí)間短、效率高、營(yíng)養損失小、基本保持了鮮奶的天然色澤和風(fēng)味。

75、In the growth of haphae, it can absorb the carbohydrate and the nitrogenous nutrients extensively.But it can't absorb the galactose, lactose, alanine, glucine and urea. ─── 在菌絲生長(cháng)階段，該菌對碳源和氮源營(yíng)養利用廣泛，但不能利用半乳糖和乳糖以及丙氨酸、甘氨酸和尿素。

76、High Density Fermentation Using Lactose as Inducer ─── 以乳糖為誘導劑的高密度發(fā)酵

77、OTHER INGREDIENTS: Lactose, Maltodextrin, Starch, Magnesium Stearate, Gelatin. ─── 其他成份：乳糖、麥芽糊精、淀粉、硬脂酸鎂、凝膠。

78、The higher lactose content in 2 layerwas, the more slowly 1 and 2 released in hydrophilic gel matrix DLT, while in mixed matrix DLT, 1 released more rapidlyand 2 released more slowly. ─── 2層乳糖用量越大,凝膠骨架雙層片中1與2釋放越慢,而混合骨架雙層片則1加快,2減慢;

79、Lactose Produced from milk, sometimes as a by product of the cheese making process . ─── 乳糖 產(chǎn)生的牛奶，有時(shí)是因為產(chǎn)品的奶酪決策過(guò)程。

80、To promote the production and consumption of milk, it is necessary to produce and popularize low lactose milk. ─── 為了實(shí)現人們“想喝奶和多喝奶”的愿望,進(jìn)行低乳糖奶的生產(chǎn)和推廣成為必然。

81、Lactose is derived form sweet dairy whey by process utilizing a specialized technique of super saturation and controlled crystallization. ─── 產(chǎn)品簡(jiǎn)介：乳糖來(lái)源于乳清，應用特殊的工藝，由飽和液控制結晶，經(jīng)過(guò)干燥得到晶體粉末。

82、In these applications, smaller molecules such as salts and lactose generally pass through the ultrafiltration membrane while proteins are retained in the concentrate. ─── 在這些應用中,小分子像鹽和乳糖等通常能通過(guò)超濾膜而蛋白被截留在濃縮物中。

83、A monosaccharide,CH2OH(CHOH)4CHO,commonly occurring in lactose and in certain pectins,gums,and mucilages. ─── 半乳糖一種單糖，CH2OH（CHOH）4CHO，一般產(chǎn)生于乳糖及特定的果酸、樹(shù)膠及膠質(zhì)物中。

84、But with lactose intolerance, it makes more consumers indigestion, distensible abdomen and so on after drinking milk. ─── 但是由于乳糖不耐癥的存在,使較多消費者飲用牛奶后會(huì )出現消化不良、腹脹等現象。

85、The major constituent of milk is water (about 87.5%) with the remainder comprising mainly fat, protein and lactose. ─── 乳中大部分是水,約占87.5%.其余主要有脂肪,蛋白質(zhì)和乳糖

86、Results showed that crude drugs such as Ginseng Radix, Glycyrrhizae Radix and Zingiber Rhizoma had serious contamination, while using starch of lactose as excipients showed lesser degree of microbial contamination. ─── 制程中造粒制程是重要的污染關(guān)鍵，與使用生藥粉末或添加生藥粉末作賦形劑、械普受污染及作業(yè)室落菌程度高有關(guān)。

87、I ate a bit of goulash, but suspecting more lactose products, and refused to eat further. ─── 我吃了一些燉牛肉，但因懷疑其他食物含乳糖而拒絕進(jìn)一步進(jìn)食。

88、The activity of disaccharide enzyme in the epidermis of intestine is letdown, to affect the absorption of lactose and other disaccharide. The disaccharide increasing to raise the osmotic pressure,and cause water diarrhea. ─── 同時(shí)小腸粘膜上皮內的雙糖酶活性減退,致腸內乳糖及其他雙糖吸收障礙,腸道內雙糖增多,滲透壓升高,水分滲出,導致水樣性腹瀉。

89、Principal constituent: Nucleotide, linolenic acid, linoleic acid, skimmed milk, lactose, lactalbumin, ingredients and so on mineral substance, Vitamin, taurine. ─── 主要成分：核苷酸、亞麻酸、亞油酸、脫脂奶，乳糖，乳清蛋白，礦物質(zhì)、維生素、氨基乙磺酸等成分。

對原核生物乳糖操縱子二重調控模式的解讀是什么？

法國巴斯德研究所著(zhù)名的科學(xué)家Jacob和Monod在實(shí)驗的基礎上于1961年建立了乳糖操縱子學(xué)說(shuō)，現在已成為原核生物基因調控的主要學(xué)說(shuō)之一。

①結構基因，能通過(guò)轉錄、翻譯使細胞產(chǎn)生一定的酶系統和結構蛋白，這是與生物性狀的發(fā)育和表型直接相關(guān)的基因。乳糖操縱子包含3個(gè)結構基因：lacZ、lacY、lacA。LacZ合成β—半乳糖苷酶，lacY合成透過(guò)酶，lacA合成**基轉移酶。

②操縱基因O，控制結構基因的轉錄速度，位于結構基因的附近，本身不能轉錄成mRNA。

③啟動(dòng)基因P，位于操縱基因的附近，它的作用是發(fā)出信號，mRNA合成開(kāi)始，該基因也不能轉錄成mRNA。

④調節基因i：可調節操縱基因的活動(dòng)，調節基因能轉錄出mRNA，并合成一種蛋白，稱(chēng)阻遏蛋白。操縱基因、啟動(dòng)基因和結構基因共同組成一個(gè)單位——操縱子（operon）。調節乳糖催化酶產(chǎn)生的操縱子就稱(chēng)為乳糖操縱子。其調控機制簡(jiǎn)述如下： ①抑制作用：調節基因轉錄出mRNA，合成阻遏蛋白，因缺少乳糖，阻遏蛋白因其構象能夠識別操縱基因并結合到操縱基因上，因此RNA聚合酶就不能與啟動(dòng)基因結合，結構基因也被抑制，結果結構基因不能轉錄出mRNA，不能翻譯酶蛋白。②誘導作用：乳糖的存在情況下，乳糖代謝產(chǎn)生別乳糖（alloLactose），別乳糖能和調節基因產(chǎn)生的阻遏蛋白結合，使阻遏蛋白改變構象，不能在和操縱基因結合，失去阻遏作用，結果RNA聚合酶便與啟動(dòng)基因結合，并使結構基因活化，轉錄出mRNA，翻譯出酶蛋白。③負反饋：細胞質(zhì)中有了β—半乳糖苷酶后，便催化分解乳糖為半乳糖和葡萄糖。乳糖被分解后，又造成了阻遏蛋白與操縱基因結合，使結構基因關(guān)閉。