【正文】 這個需求量。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 in malnutrition in the presence of an adequate diet. 吸收和運輸機制發(fā)揮正常功能對于把消化系統(tǒng)降解的分子運輸?shù)矫總€細胞有重要的意義。s structure adjusts to the substrate39。 acid as a source of H+ will catalyze the formation of any ester from the appropriate alcohol and carboxylic acid, but many enzymes are so specialized that they will catalyze a reaction of one molecule, but will leave untouched a very similar molecule.硫酸作為一個H+離子來源，能催化任何由合適的羧酸和醇構(gòu)成酯的反應，而許多酶的特性很高，它們可以催化一種分子反應，但不會觸及另一類很相似的分子的反應。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.飽和脂肪有一個均一一致的形狀，這使得他它們能夠在晶格中聚合起來。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.蠟是一種由長鏈羧酸和長鏈醇通過脂鍵組成的酯的混合物。8. Thus we 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 interactions, and salt bridges.這樣我們能從蛋白質(zhì)一級，二級，三級和四級結(jié)構(gòu)方面來描述酶：它們是由氨基酸通過肽鍵結(jié)合的單位所組成，以纏繞折疊的方式，由二硫鍵，疏水鍵，鹽橋而構(gòu)成二級和三級結(jié)構(gòu)的許多長鏈。在這種方式中，營養(yǎng)素組成機體的有機部分，并依據(jù)控制他們行為的生理和生化過程，發(fā)揮他們的功能。這個過程包括了攝入消化食物，和吸收與應用，或者代謝食品中的營養(yǎng)素。 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被設(shè)置成高標準，可以確保如果食物中營養(yǎng)素的量能達到這個標準，它們也會滿足需求量最高的個體的要求。例如加入到油抗氧化劑能阻止氧化變臭，防腐劑阻止食品的腐敗，著色劑是食品具有更吸引人的外觀等等