D) Long chains of amino acids used for building, repair, and maintenance
Proteins are made up of amino acids, and they are used to create substances (like hair, nails, etc.)
Hope this helps!!
 
        
             
        
        
        
I believe it's a. hydrogen bond
        
                    
             
        
        
        
They are all not plate tectonics
        
             
        
        
        
Carbon dioxide and oxygen
        
                    
             
        
        
        
Answer:
Addition of a(n) methyl group to certain lysine residues of a histone protein makes the region of chromatin transcriptionally silent; addition of a(n) acetyl group to certain lysine residues makes the region of chromatin transcriptionally active.
Explanation:
The changes suffered in the expression and activity of the genes are studied by the Epigenetics.