Tutor profile: Thomas A.

Which amino acids contain a non-polar, aliphatic R-group?

glycine, alanine, leucine

What is the general mechanism by which blood sugar is regulated in the human body?

Like most processes in the human body, blood sugar must be regulated in homeostasis (or dynamic equilibrium). This is accomplished by the help of several organ systems. However, the primary organ we need to focus in on for this question is the pancreas. And in particular, we need to focus on the hormones that are secreted from the pancreas, in particular insulin and glucagon. First, let's consider when blood sugar is low - what must the body do? It must find a way to increase the blood sugar levels and this is accomplished by secreting glucagon from the alpha cells found in the islets of Langerhans. When glucagon is released, it acts upon the glycogen stores found in the liver. Glycogen is basically the storage form of glucose (sugar) for the human body. And one of the primary storage sites for glycogen is the liver (the other is muscle cells). Once glucagon reaches the glycogen stores in the liver, it initiates a chemical reaction that transforms the glycogen molecule back into glucose. This glucose is then released into the bloodstream and the blood sugar levels return back to normal? Then what happens in the opposite situation when blood sugar is to high (right after a meal for example)? After a meal is consumed, the blood sugar levels are elevated. Therefore, the pancreas secretes insulin to lower these levels back to normal. Insulin is also secreted from the alpha cells from the islets of Langerhans. When secreted, insulin attaches to the receptors found on the outer membrane of the cells around the body. This attachment initiates a secondary messenger system within the cell that tells glucose transporters to go to the cell surface and allow the glucose into the cell. Then once the blood sugar levels return to normal, the transporters leave the surface of the cell and this new glucose that is in the cell is used for energy and normal cellular function. Think of insulin and glucagon as opposite working hormones that both strive to maintain stable blood glucose levels.

For this equation, how would we get the variable by itself? 2x = 3(x + 1)

The first thing we want to do is remember our order of operations. PEMDAS (Parenthesis, exponents, multiplication, division, addition, subtraction). Therefore, the first thing we want to do is distribute the 3 to the values in the parenthesis. 2x = 3x +3 Next, we want to bring all the "x's" to one side. Therefore, we should undo the addition on the right side by subtracting the "3x" from each side and we will be left with a "-x" on the left side of the equation. -x = 3 To finish of the problem, we need to remove that "-" sign from the "x". Therefore what we need to remember here is "-x" is the same thing as "-1x". Therefore we need to either multiply or divide each side my "-1" to remove the negative sign. And when we divide or multiply the "3" by "-1" then that "3" will become "-3" x = -3