A-level生物| 那些生物里的化学反应！

A-level生物| 那些生物里的化学反应！

众所周知，生物和化学的关系密不可分，可谓是你中有我，我中有你。

考试的时候，也经常会要求学生写出某个reaction或者某个bond的名字。具体来讲，我们需要掌握如下几种bond：

·glycosidic bonds in carbohydrate structure.

·peptide bonds in polypeptide structure.

·ester bonds in lipid structure.

其中，glycosidic, peptide and ester bonds are formed by a process called condensation. 在合成反应中经常发生。

The reverse process, involved in digestion, is hydrolysis, which is the splitting of molecules by the addition of water.

那么我们接下来分别看看这几种bonds的形成过程：

1.Formation of glycosidic bonds

These are the bonds which join single sugars (monosaccharides) together to form double sugars (disaccharides) and multiple sugars (polysaccharides).

比如在maltose的合成过程中，涉及到两个α-glucose的condensation形成1,4 alpha-glycosidic bond。

而在cellulose的合成过程中，涉及到很多个beta-glucose的condensation reaction形成1,4 beta-glycosidic bond.（这里仅仅以两个beta-glucose之间的link为示意）。

2．Formation of peptide bonds

Peptide bonds are formed by condensation between the acid group of one amino acid and the amine group of another amino acid. They enable amino acids to be joined into long chains called polypeptides.

3.Formation of ester bonds in lipid structure

An ester bond is formed by condensation between an acid and an alcohol. The main alcohol involved in lipid structure is glycerol (which has 3 alcohol or –OH groups) and the acids involved are fatty acids.

这几种bonds和他们的reaction所形成的的产物，作为最基础的部分，请各位同学们反复强化复习吧！