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1、Lesson 91. Lipids are a family of naturally occurring compounds grouped together on the basis of their relative insolubility in water in nonpolar solvents. These are naturally occurring molecules that can be isolated from cells and tissues by extration using nonpolar organic solvents.依据在水中的不溶解性和在非极性
2、溶剂中的溶解性,脂肪以家族形式组成而自然出现的。这些天然存在的分子可以通过采用非极性有机溶剂萃取的方法,在细胞和组织中分离得到。2. Saturated fats have a uniform shape that allows them to pack together in a crystal lattice. Unsaturated fats have double bonds that introduce kinks into the hydrocarbon chain making crystal formation more difficult.饱和脂肪有一个均一一致的形状,这使得
3、他它们能够在晶格中聚合起来。不饱和脂肪有双键能使烃链发生扭曲,从而使晶体的形成更加困难。3. The most abundant lipid in olive oil is glyceryl trioleate, a trimester formed from glycerol and oleic acid, a mono-unsaturated fatty acid with a cis double bond in the middle of the C18 chain.橄榄油里最丰富的脂质是三油酸甘油酯,是甘油和油酸,与一个单不饱和脂肪酸加上一个顺式双键在C18链的中间形成的一种三聚体。
4、4. Waxes are mixtures of esters of long chain carboxylic acids and long chain alcohols. The carboxylic acids usually have an even number of carbon atoms, ranging from 16 to 36, and the long chain alcohols also have an even number of carbon atoms, ranging from 24 to 36.蜡是一种由长链羧酸和长链醇通过脂键组成的酯的混合物。长链羧酸通
5、常由偶数个(1636个)C原子组成,而长链醇也是由偶数个(2436个)C原子组成。 Lesson105. This means that any catalyst that catalyze a reaction in one (e.g.,esterification) also catalyze the reverse(e.g., ester hydrolysis) reaction. To say these things another way, catalysts do not change the energy balance between reactants and produc
6、ts; catalysts do lower the energy barrier between reactants and products.这意味着任何一个催化剂既可以催化一个反应朝一个方向进行,也可以使其朝逆方向进行。换句话说,催化剂不会改变反应物与产品之间的能量平衡,只是降低反应物与产品之间的能量差值。6.Sulfuric acid as a source of H+ will catalyze the formation of any ester from the appropriate alcohol and carboxylic acid, but many enzymes a
7、re so specialized that they will catalyze a reaction of one molecule, but will leave untouched a very similar molecule.硫酸作为一个H+离子来源,能催化任何由合适的羧酸和醇构成酯的反应,而许多酶的特性很高,它们可以催化一种分子反应,但不会触及另一类很相似的分子的反应。7. This broader specificity is useful in the case of an enzyme like papain which is important in protein di
8、gestion. It can catalyze the hydrolysis of peptide (amide) bonds in a variety of proteins, which means that the body does not need to maintain a stock of more specific enzymes to tackle specific proteins.这个广泛的特异性在酶中很有用,例如木瓜蛋白酶,它在蛋白质消化中具有重要意义。木瓜蛋白酶可以在各种蛋白质中催化肽键的水解,从而可使人体不需要更高特异性酶来专门水解特殊的蛋白质。8. Thus w
9、e can describe them in terms of their primary, secondary, tertiary, and in many cases, quaternary structure. They are long chains of amino acid units held together by peptide bonds, looped and folded into secondary and tertiary (and often quaternary) structures by disulfide bonds, hydrophobic intera
10、ctions, and salt bridges.这样我们能从蛋白质一级,二级,三级和四级结构方面来描述酶:它们是由氨基酸通过肽键结合的单位所组成,以缠绕折叠的方式,由二硫键,疏水键,盐桥而构成二级和三级结构的许多长链。9. In such instances, the enzyme without the cofactor is called an apoenzyme, and the apoenzyme-cofactor complex is called a holoenzyme. We will see that the protein chain of an apoenzyme ca
11、n have functional groups on its side chains (R groups) which are important to its catalytic function, but other important functional groups are introduced by way of cofactors.有些时候,不含辅基的酶叫脱辅基蛋白酶,辅基和脱辅基蛋白酶的复合物叫全酶。我们将发现由脱辅基蛋白酶组成的蛋白质链的侧链上,具有对它的催化功能起重要作用的功能基团,但其他重要的功能基团则是由催化剂的辅基提供。10. The fit can come ab
12、out either because the molecule fits easily into the enzyme's active site (lock-and-key model) or because the enzyme's structure adjusts to the substrate's entry (induced fit model). 匹配进入酶的活性部位,要么因为这个分子容易进入酶的活性部位,要么因为酶的结构进行调整。Lesson 1111. These provide the energy and building materials f
13、or the countless substances that are essential to the growth and survival of living things. The manner in which nutrients become integral parts of the body and contribute to its function is dependent on the physiologic biochemical processes that govern their actions.这些营养素为无数的生物生长和生存所必需的物质提供了能量和构建物质。
14、在这种方式中,营养素组成机体的有机部分,并依据控制他们行为的生理和生化过程,发挥他们的功能。12. As constituents of food we eat they not only provide energy but also provide a basis for tastes, color, texture, keeping qualities, and overall acceptability of that food, not nutrients, and therefore should consider the total role of nutritional com
15、pounds in food.作为我们所吃食物的组分,它们不仅提供了能量,而且提供了该食物的味觉、颜色、质地、质量保持和总的接受程度。不能遗忘的是我们吃的食物不是营养素,因此我们应当考虑到食物中营养化合物总的作用。13. They are called essential nutrients because we cannot get along without them .We need them for energy for building and maintaining body tissue, and for regulating body processthe three esse
16、ntial functions of food in the body. 因为我们的生存离不开它们,所以被认为是必须的营养素。我们需要这些营养素提供能量、建造和维持身体组织、调节生理反应,这就是食品必须营养素在身体中的三大功能。14. Proper function of the absorptive and transport mechanisms is crucial to delivering the products of digestion to the individual cells. Derangements of any of these systems can result
17、 in malnutrition in the presence of an adequate diet. 吸收和运输机制发挥正常功能对于把消化系统降解的分子运输到每个细胞有重要的意义。任何对这些系统的扰乱都能导致一个适当的饮食营养失调。15. Nutrition might be defined as process whereby we obtain the essential nutrients and use them to make many other substances our bodies need. This process would include eating dig
18、esting food absorbing and using, or metabolizing, the nutrients it contains.吸收营养素可以被定义为我们所吸收的营养素和利用他们去组建我们需要的其他物质的一个过程。这个过程包括了摄入消化食物,和吸收与应用,或者代谢食品中的营养素。16. Each of these nutrients contains carbon, hydrogen, and oxygen, while protein also contains nitrogen and it is the ratio of carbon to hydrogen to
19、 oxygen that determines the number of calories they provide. 这些营养素含有C、H、O,蛋白质还含有N,并且C、H、O的比例决定了他们提供能量的大小。17. Is more always better or is there an optimum intake below which deficiency might result and above which toxicity could be caused? Indeed, there is an optimum amount. Deficiencies do occur and
20、 death can result from too much of some of the nutrients.是不是越多越好,还是有一个最佳摄取量,低于该值会导致营养不良,高于则会累积毒素?事实上,是有一个最佳摄取量。但是过量的摄取某种营养素便会暴露缺陷和导致死亡。18. However, how can we determine the exact requirement for nutrients for each individual since we are all different? The answer is that the exact requirement cannot
21、 be calculated; we would have to study each individual on the earth in a hospital setting to find such requirements.然而,我们每个个体都是不同的,那如何去确定每个不同个体的营养素确切的摄入量呢?答案是确切的摄入量是不可以被计算出来的;我们必须在医院的设备环境下来找到这个需求量。19. These recommendations are not individual requirements but are “recommendations for the average dail
22、y amounts of nutrients population groups should consume over a period of time”. As such, they designed to provide assistance in large scale foodservice operations so that the nutrients in the food offered each day could be compared to the RDA.这些推介量不是个体需求量,而是“这个群体在一定时间内所需要消耗的营养素的日需量推介”。照此理解,他们被设计成为为大
23、规模食品服务业提供支持服务,从而每天所提供的食品营养素才可以参照RDA的标准。20.The RDA, therefore, were set high enough to ensure that, if quantities of nutritients in the food being served met this standard, they would meet the needs of individuals with the highest requirements.因此,RDA被设置成高标准,可以确保如果食物中营养素的量能达到这个标准,它们也会满足需求量最高的个体的要求。21.
24、 Using the RDA as standards for evaluating the adequacy of nutrient intakes is like setting the standard for height 7 feet and assuming that all of those under7 feet have suffered growth retardation.运用RDA作为衡量营养素是否充足的标准就像给身高为7英尺的人设定标准,并且假定那些低于7英尺的人遭受生长延迟。Lesson 1222.The concept of food safety has man
25、y facets。Perhaps the most obvious, and certainly the most prevalent problem of food safety is microbiological food poisoning. This is a serious in nearly every country, but another aspect of food safety is primarily concerned with chemicals.食品安全的概念包含很多方面,最显而易见和最普遍的食品安全问题是微生物食品污染,这是在每个国家都有的重要问题,但其他方面
26、的食品安全主要和化学药品有关。23. Chemicals in our food supply come from six sources. They are industrial accidents, intentional fraud, natural compounds, food additives, pesticides, and environmental pollutants. All require a different concept of food safety a different approach.在我们食品供应的化学物质来源于六个方面,他们是工业事件,认为欺骗,自
27、然化合物,食品添加剂,农药以及环境污染物质。每一个方面在食品的概念中有不同的侧重点。24. Toxicants occurring naturally in foods are not subject to regulatory control, and many would not receive approval if they were proposed as food additives at the level in which they occur.食物中自然出现的有毒物质是不需要经过管理控制,并且如果以它们出现的水平,把许多这些物质提议作为食品添加剂是不会被同意的。25. The
28、 compounds added to foods for special purposes are called food additives. Examples are antioxidants added to oils to prevent rancidity, preservatives to prevent food from spoiling, colorants to make food more appealing, etc. Most of these chemicals are generally regarded as necessary and safe.这些有目地加
29、入到食品当中的物质被称为食品添加剂。例如加入到油抗氧化剂能阻止氧化变臭,防腐剂阻止食品的腐败,着色剂是食品具有更吸引人的外观等等。大多数这些化学物质一般被认为是安全和有必要的。26. To obtain approval of a particular pesticide, the manufacturer must supply the EPA with data from toxicological studies, residue data, and justification of use in terms of economics and an adequate food suppl
30、y. A risk-benefit analysis leads to rejection or acceptance and establishment of a legal tolerance. 为了获得一种杀虫剂的使用批准,制造商必须把毒物学研究数据,残余量数据,以及从经济和充足的食物供应方面的使用理由提供给EPA,一项风险-利益的分析决定这种杀虫剂是被拒绝,还是被接受并建立起合法的使用限度。27. Four times each year, 234 food items representing the diets of American consumers are purchased in different cities around the United St
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