The following are the environmental factors that can damage genes that code for these enzymes. radiation from sun, various chemicals and x-rays. these agents are referred to as environmental mutagens. they result to changes in the genetic make up of the organism and in  turn affect the production of enzymes. enzymes are protein in nature and once the DNA has been compromised their production is affected. in most cases mutated DNA produces enzymes with lost or abnormal function. 
        
                    
             
        
        
        
The tissue in the wall of the uterus that is required for labor contractions are SMOOTH MUSCLES. Smooth muscles, also known as involuntary muscles are found in walls of hollow organs such as the stomach, gullet, bronchi, etc. Smooth muscles principally function as stimulator for movement. Examples of smooth muscles in the human body include:
1.Uterus smooth muscles: enhancing pushing during birth labour
2. Bladder smooth muscle: helps push out urine.
3. Smooth muscles also help the flow of blood in the blood vessels and the flow of food through the digestive system.<span />
        
             
        
        
        
I dont know if have this but... i have this questio and it is c