Stimulants are substances that all result in the increase of levels of dopamine in the brain, which is a neurotransmitter that affects attention and pleasure. What this means is that stimulants affect our brain and the way it works by changing the ways that nerve cells communicate. 
Neurons (nerve cells) are the cells that have a role in transmitting messages from the brain to other parts of our body, and vice-versa, which is important for pain response, alertness, energy etc. 
With long-term use, the use of stimulants would affect the central nervous system (speeding it up), the brain, and the functions necessary to live, like respiration, heart rate, blood pressure, body temperature. Levels of neurotransmitters like dopamine, serotonin, and GABA, which are responsible for the regulation of different processes,  are also impacted, which creates a chemical disbalance ultimately resulting in behavioral changes, mood swings, altered attention, movement and energy, stress etc.
So the part of the body that is affected the most with the long-term use of stimulants like cocaine, nicotine, methamphetamine is the brain of course, which is where these substances have the most impact, but the impact on the central nervous system, autonomous nervous system, and neurotransmitter levels is significant.
        
             
        
        
        
Nucleic acids are the biopolymers, or large biomolecules, essential to all known forms of life. The term nucleic acid is the overall name for DNA and RNA . They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base.
 
        
             
        
        
        
<span>The structure of a paramecium that holds a "reserve copy" of all the cell's genes is the micro nucleus.
</span>The micro nucelus is one of the <span>two kinds of </span>nuclei the paramecium has. The other is the<span>  large ellipsoidal </span>nucleus<span> called a macronucleus. Every paramecium must have at least one small </span>nucleus<span> called a </span>micronucleus. The micronucleus is a storage site for the germline genetic material of the organism.
        
                    
             
        
        
        
Cells need water to survive for a dispose of waste