什么是代谢
现生生物每个细胞内发生的化学反应总和,供应生命所需能量并合成新的细胞物质。「中间代谢」论及庞大网状的互相联系的化学反应,藉此产生或消灭所有细胞的组成,许多成分在细胞外面极为罕见。同化反应(合成代谢作用)利用能量从较简单的有机化合物建造复杂的分子(如氨基酸变成蛋白质,糖变成碳水化合物,脂肪酸和丙三醇变成脂肪);异化反应(分解代谢作用)将复杂的分子分解成较简单的分子,释放出化学能。对大多数生物而言,能量总归是来自太阳,不管是由光合作用取得储存在有机化合物之间,或是吃这些光合作用的生物消耗其储存的有机化合物。有些特殊环境的细菌,例如在深海裂口,能量是由化学键结。在细胞内或生物体内,能量是由三磷酸腺来传递;同化反应消耗三磷酸腺,异化作用则生成。每个细胞化学反应是由特定的居间协调。物质分解作用通常是不可逆的作用,因此需要不同的。亦请参阅digestion、fermentation、tricarboxylic acid cycle。
metabolism
Sum of all the chemical reactions that take place in every cell of a living organism, providing energy for the processes of life and synthesizing new cellular material. “Intermediary metabolism” refers to the vast web of interconnected chemical reactions by which all the cell's constituents, many rarely found outside it, are created and destroyed. Anabolic reactions use energy to build complex molecules from simpler organic compounds (e.g., proteins from amino acids, carbohydrates from sugars, fats from fatty acids and glycerol); catabolic reactions break complex molecules down into simpler ones, releasing chemical energy. For most organisms, the energy comes ultimately from the sun, whether they obtain it by photosynthesis and store it in organic compounds or consume those that photosynthesize for the energy stored in their organic compounds. In some bacteria in special environments such as deep-sea vents, the energy comes from chemical bonds instead. Energy is transferred within the cell and the organism by ATP; anabolic reactions consume it, and catabolic reactions generate it. Every cellular chemical reaction is mediated by a specific enzyme. The process that breaks down a substance is not usually the reverse of the process that makes it and uses a different enzyme. See also digestion, fermentation, tricarboxylic acid cycle.
-
野无遗才是什么意思?
意思是:见“野无遗贤”。成语名字:野无遗才成语发音:yěwúyícái成语解释:见“野无遗贤”。成语出处:《魏书·阳尼传》:“举贤良,黜不肖,使野无遗才,朝无素餐。”成语繁体:野無遺才感情色彩:中性成语成语用法:作宾语、定语;指爱惜人才成语结构:偏正式成语产生年代:古代成语...
-
异想天开是什么意思?
意思是:异:奇异、奇特;天开:比喻凭空的;根本没有的事情。形容想法非常离奇、荒唐。或指解放思想。成语名字:异想天开成语发音:yìxiǎngtiānkāi成语解释:异:奇异、奇特;天开:比喻凭空的;根本没有的事情。形容想法非常离奇、荒唐。或指解放思想。成语出处:清吴趼人《二十年...
-
严家饿隶是什么意思?
意思是:形容拘谨的书法风格。语出《晋书·王羲之传论》:“献之虽有父风,殊非新巧。观其字势,疏瘦如隆冬之枯树;览其笔踪,拘束若严家之饿隶。”成语名字:严家饿隶成语发音:yánjiāèlì成语解释:形容拘谨的书法风格。语出《晋书·王羲之传论》:“献之虽有父风,殊非新巧。...
-
以为后图是什么意思?
意思是:为以后作打算。成语名字:以为后图成语发音:yǐwéihòutú成语解释:为以后作打算。成语出处:《左传·桓公六年》:“斗伯比言于楚子曰:‘……汉东之国随为大,随张,必弃小国。’小国离,楚之利也。少师侈,请羸师以张之。熊率且比曰:‘季梁在,何益?’斗伯比曰:‘以为后图,少...