. Botany of the living plant. Botany; Plants. [26 . B01 VNY OF THE LIVING PLANT P ITEIN S HESIS. Proteins and carbohydral re the most important constituents of the plant body, though there is In addition a great range of sub- Btan >ther typ< •- we saw in Chapter III., the especial im- portan proteins lies in the fad that the living substance, proto- plasm, i- largely made up from them. Chemical analysis shows that proteins and their derivatives may account for as much as 60 per •it. of the dry weight <<t protoplasm. The protein molecule contains the elements carbon, hydrogen, oxyge
. Botany of the living plant. Botany; Plants. [26 . B01 VNY OF THE LIVING PLANT P ITEIN S HESIS. Proteins and carbohydral re the most important constituents of the plant body, though there is In addition a great range of sub- Btan >ther typ< •- we saw in Chapter III., the especial im- portan proteins lies in the fad that the living substance, proto- plasm, i- largely made up from them. Chemical analysis shows that proteins and their derivatives may account for as much as 60 per •it. of the dry weight <<t protoplasm. The protein molecule contains the elements carbon, hydrogen, oxygen, nitrogen and sulphur (the latter in very small proportion). It ia an dingly complex structure with a molecular weight running into many Ji Fig. 84. A great many different pro- teins have been detected in plants, and each plant con- tains a variety of them. They are all built up in the main from Amino-acids. These are organic acids containing the amino group, - NH2. Glycine, A, cell from the endosperm of Ricinus in water, Acnarrir Arirl Trwr^rnT^ricm^ which causes the outer coat of the aleurone grains to ^P^rL1(- AUU, irypiopnane swell. B. isdated .ilcurone grains in oil. A: = albumen „nrl fVQfinp mo\r hp nampH tab. g globoid (> 540.) (After Strasburger.) dnu ^yatme mav De namea as examples. Some of these amino-acids are themselves quite complex, but it is probable that several hundreds of amino-acid molecules are required for the forma- tion of a single protein molecule. Certain proteins, distinguished as iVwc/Voproteins, contain phosphorus in addition to the above elements. The nuclear structures of the cell are believed to con- sist largely of these. As mentioned in Chapter III., proteins give colloidal solutions, and it is doubtless in this state that proteins are t-nt in the protopla-m. In addition to the protoplasmic proteins there are also reserve ems, regularly presenl in seeds and other storage organs either in a crystalline form (Fig. 81), or in
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