Metabolic Pathways & Their Control

Click on a number in the grid to see the clue or clues for that number.
Complete the crossword, then click on "Check" to check your answer. If you are stuck, you can click on "Hint" to get a free letter.

                   1   
2              3          
                    
           4      5       
   6                   
  7                 8     
                    
9            10            
                    
       11               
 12      13                14   
                    
15   16           17            
                    
                    
    18                  
                    
      19                
                    
     20                 

Across:

2. The chemical(s) on which an enzyme reacts. (9)
3. Intermediate metabolite at the start of respiration. (8)
4. The gene which codes for the repressor molecule in the lac operon. (9)
7. The first stage of respiration. (10)
9. Chemical which prevents an enzyme from working. (9)
10. Gene to which the repressor attaches in the absence of a substrate. (8)
12. The plasma membrane has a double layer of these molecules. (12)
15. Reaction which is responsible for the breakdown of a substance. (9)
18. Site of aerobic respiration. (13)
19. The principal respiratory substrate. (7)
20. Movement of molecules against the concentration gradient. (6,9)

Down:

1. Protein molecule which sticks to the operator gene. (9)
2. One enzyme fits one substrate and is said to be ______________ . (8)
5. Something which slows down the rate of a reaction or stops the reaction. (8,6)
6. The model used to describe the plasma membrane. (5,6)
8. The gene which codes for the enzyme production in the lac operon. (10)
11. Another name for a poison. (5)
13. Large molecule found within the plasma membrane. (7)
14. When the active site of an enzyme changes slightly to accept the substrate. (7,3)
16. Reaction which builds up complex molecules and requires energy. (8)
17. Membrane-bound organelle which encloses enzymes. (8)