想請問一下有關於還原糖的問題
回答 (3)
2010-06-22 10:42 pm
✔ 最佳答案
rain 君:maltose 轉成 glucose 係 [水解] = hydrolysis 而唔係 [還原] = reduction
你將兩件不同既事搞錯左啦.
hydrolysis 既相反係 condensation
reduction 既相反係 oxidation.
所以, 還原其實係講緊一樣物質, 可以被氧化, 之後既 [還原]
還原/氧化作用, 合稱 Redox reaction氧化還原反應 = REDuction + OXidation
所以, 想定義還原糖, 就應該向redox 方向查.
除左maltose, glucose呢d, 仲有好多野有能力將人地reduce, 統稱為還原劑 reducing agent. 眾多既reducing agent 之中, 佢地屬於糖類, 因此就有 還原糖 reducing sugar 呢個名.
顧名思義, 將一d氧化左既野還原喎, 即係reducing sugar喜歡攞走人地既氧囉. 還原糖有 RCHO, 將人地還原將自己氧化, 就變成左 RCOOH 即係變成酸 acid, 如[葡萄糖] 就會變成 [葡萄糖酸]
維基中文版不及英文版詳細, 睇呢度啦:
http://en.wikipedia.org/wiki/Reducing_sugar
A reducing sugar is any sugar that, in a solution, has an aldehyde
or a ketone
group. This allows the sugar to act as a reducing agent
維基中文版的定義:
還原糖泛指一些有還原能力的糖。
一般情況下，單糖的還原能力主要來自它的醛基，如葡萄糖，而多糖則
大多因為半縮醛羥基的存在。
===
Monosaccharide 已可以直接被人體吸收及使用. 吸收後會去到粒線體進行細胞呼吸cellular respiration, 做好多步驟既 modification, 最終變成水和二氧化碳, 經肺部排出體外. 所以, 總體來講, 身體將monosaccharide 拆成 [水] 和 [二氧化碳] , 都算係broken down 啦!
參考: 維基百科
2010-06-19 11:28 pm
In chemistry, RCHO can be oxidised to RCOOH by mild oxidizing regents.
The reducing property of glucose, for example, is in the form of chain structure while there is an equlibrium between the ring and chain structure.
However, for some sugars such as sucrose which is formed by condensation of two monomeric sugars, the bonding between the two sugar units is at the position of CHO! So, in the form of chain structure, there is no CHO and so not reducing.
I suggest u to refer to some structures.
Go wiki and type glucose.
2010-06-19 15:33:29 補充：
monosaccharide only can be broken down by very strong chemicals but not our body.
u can refrer monosaccharide such as Glucose as G, then two G can form G-G by condensation and the bond between G can be broken down by some enzymes in our body. Similarly, G-G-G..can also be understood by this analogue.
The reducing property of glucose, for example, is in the form of chain structure while there is an equlibrium between the ring and chain structure.
However, for some sugars such as sucrose which is formed by condensation of two monomeric sugars, the bonding between the two sugar units is at the position of CHO! So, in the form of chain structure, there is no CHO and so not reducing.
I suggest u to refer to some structures.
Go wiki and type glucose.
2010-06-19 15:33:29 補充：
monosaccharide only can be broken down by very strong chemicals but not our body.
u can refrer monosaccharide such as Glucose as G, then two G can form G-G by condensation and the bond between G can be broken down by some enzymes in our body. Similarly, G-G-G..can also be understood by this analogue.
2010-06-19 4:02 am
還原糖姐係reducing sugar~可以被還原
for instance : maltose 分解變glucose
A sugar is only a reducing sugar if it has an open chain with an aldehyde or a ketone groupA 呢d你應該唔洗知
你只係要知佢可以用本立德指示劑驗到出黎..如果係還不糖會變色
2010-06-18 20:03:38 補充：
還原糖--打錯字都係用英文好
for instance : maltose 分解變glucose
A sugar is only a reducing sugar if it has an open chain with an aldehyde or a ketone groupA 呢d你應該唔洗知
你只係要知佢可以用本立德指示劑驗到出黎..如果係還不糖會變色
2010-06-18 20:03:38 補充：
還原糖--打錯字都係用英文好
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100617000051KK01211