164 



Inside the Living Cell 



CH 



CH, 



./V^N/°°\ 



NH**--- -•Acid Group / 



I 

 CO • 



\^n/\,/ 



Part of protein molecule 



I • 



d-Ribo oo - phospho-group— Basic Group '. 



Figure 3. The riboflavin phosphate molecule showing how it 

 combines with the protein part of the enzyme. 



NH, 



NH2 



COOH 



p-Aminobenzoic Sulfanilamide 

 acid 



SO2NH2 



Figure 4. A vitamin and its antagonist. 



c c c 



/ ^ / \^/ \^ 

 c c c c 



\ I I / 



C_N N— C 



/ \ / "^^ 



C Fe C 



\ / \ / 



C—N N— C 



c c c c 



\ / \ / \ / 



c c c 



The central haem part 

 of haemoglobin 



i i 



I 

 C 



/ \ / \ / \ 



c c c c 



\ I I / 



C—N N— C 



\ / \ 



Co C 



/ \ / 



C—N N— C 



/ \ i \ 



— c c c c 



\ / \ / \ / 



c c c 



I I I 



The central part of 

 Vitamin BI2 



Figure 5. The central parts of the molecules of haemoglobin 

 and vitamin B12. 



