CARBOHYDRATES 



145 



Carbohydrates. — Con. 



Monosaccharids. 



Arabinose 



C5H10O5, (CH2(0H)-(CH- 



(0H))3-CH0) 

 d-Glucose (grape sugar, dex- 

 trose) 



CeHioOe, (CH2(0H)-(CH- 



(0H))4-CH0) 



d-Galactose (formula as for glu- 

 cose) 



d-AIaniiose (formula as for glu- 

 cose) 



d- Fructose (fruit sugar or levu- 

 lose) 

 CfiHioO,;, (CH,(0P^)-(CH- 

 (0H))3-C0-CHo(0H)) 

 10 



taste and dialyze easil}'. The 

 solubility and sweetness as 

 well as i)ower to dialyze 

 decrease as the numl^er of car- 

 bon atoms increases. Those 

 with Ce (or C5) are called 

 monosaccharids; with C12, di- 

 saccharids or bioses; Cis, tri- 

 saccharids or trioses; C24, 

 tetrasaccharids or tetroses; 

 those with larger value of car- 

 bon are often termed poly- 

 saccharids. They usually have 

 the formula (C6Hio05)n. 

 Only the commoner forms 

 will be mentioned. 

 Obtained by treatment of 

 various gums with dilute 

 boiling H2SO4. 



This is the commonest sugar. 

 It is in most cases the first car- 

 bohydrate produced in pho- 

 tosynthesis. It occurs alDun- 

 dantly in most sweet fruits. 

 It is the form in which carbo- 

 hydrates are translocated. 

 Produced b}^ the splitting of 

 the lactose, raffinose, or man- 

 neotetrose molecule by weak 

 acids, therefore one of the 

 constituents of these sugars. 

 Produced by the splitting of 

 the molecule of certain (re- 

 serve) celluloses by weak acida 

 and therefore one of the con- 

 stituents of those carbohy- 

 drates. 



This sugar is abundant in 

 many sweet fruits, e.g. graj)e. 



