They must occur in the DNA, which is in each cells nucleus. More specifically the nucleolus of the cell. A mutation occurs in an allele, where a base triplet (or a codon) gets transcribed incorrectly.
        
             
        
        
        
<span>The major structure that supplies the cells with nutrients and removes their waste is the circulatory system. The circulatory system is composed of the heart, the blood vessels going from and back to the heart, and the blood that travels inside them. The blood vessels that carry nutrient and oxygen-rich blood to the cells are arteries. They become the thinner arterioles, and then the thinnest capillaries. With the exception of the pulmonary arteries, which carry non-oxygenated blood from the heart to the lungs, all arteries carry oxygenated blood. The capillaries disburse the nutrients and oxygen to the cells and pick up wastes and carbon dioxide, form into the thicker venules, then to form veins, which lead back to the heart (with the exception of the pulmonary veins, which carry oxygenated blood from the lungs to the heart). Veins also differ from arteries in that veins have valves to prevent blood from flowing backward.</span>
        
             
        
        
        
I believe that the government should have limited access to people's genetic codes as they might be useful in solving crime or figuring out someone's identity and relatives
        
             
        
        
        
<span>Once the cytoplasm of the amoeba is moving, all the cells in the said cytoplasm will move as well. Consequently all the cell organelles can be seen changing positions. The cytoplasm’s ability to move is dependent on the entire composition of cell organelles that make up the said cytoplasm.</span>