The order that the nucleotides are arranged in form different "codes" to create traits. RNA in humans is used for transporting, and making the amino acid proteins. The order of amino acid proteins also changes the polypeptide formed, and changes more traits, and characteristics. Basically, it's like reading a book. Each book is made up of the same 26 letters, but their all arranged in different orders. You can find the some of the same words in another book, but no two books are exactly alike. All the letters and words are arranged in different ways, even though other books have the same letters and words.
The mitochandria's main function is to produce ATP through cellular respiration.
The short answer is that cells respond to the chemical environment in which they find themselves. The cells around them, the specific conditions, and feedback from the environment all create specific chemical cues that inform the cells to which genes should be expressed, and in what amounts. Chemicals include hormones, cytokines, general signaling molecules, such as cAMP, etc.
i literally hopped on google for this, lol.
i hope this helps though. :)
