Protein Synthesis: Regulation

Transcription is actually much more complicated.  How does RNA polymeraseAn enzyme that synthesizes RNA from a DNA template. know where to attach?  How does it know when to detach? 

For example, gray hairs.  Gray hairs are the result of a gene that starts to become transcribed.  It’s a gene you always had, but it’s been turned on like a light bulb.  You didn’t always make the proteinsLarge molecules made of amino acids with various functions in the body. that made that white pigment, but some stressful event in your life turned it on.  This could be an emotionally stressful event a traumatic event, or this could also be a physically stressful event such as a surgery or childbirth.  What happens is that there are these little proteins called transcription factors that can either initiate transcription or prevent transcription.  In our analogy of gray hairs, maybe a negative transcription factor or a repressor that prevents transcription is removed by the stressful event or maybe a positive transcription factor called an activator that initiates transcription is added.  Either way, transcription starts. 

There are many hormones that the human body makes that are called antagonistic hormones.  Most of these are peptide hormones derived from proteins.  Insulin, the glucoseA simple sugar that is the main source of energy for cells. lowering hormone and glucagonIncreases blood sugar by promoting glycogen breakdown., the blood glucose raising hormone fall into this category.  When your blood glucose goes above a certain level, the cellsThe basic structural and functional units of life. in your pancreasA gland that produces digestive enzymes and hormones like insulin and glucagon. make insulin.  When your blood glucose goes below a certain level, the cells in your pancreas make glucagon.  Put another way, when your blood glucose goes up, positive transcription factors are put onto your genes that make insulin and insulin is made.  When your blood glucose goes down negative transcription factors are put onto the genes that make insulin, stopping its production.