AP BIOLOGY

Detailed explanation-1: -The internal regulators are proteins inside of the cell while external regulators are proteins outside of the cell. Internal regulators will determine if the internal state of the cell is ready for cell division or not. If it is, then it allows division to proceed. If it isn’t, then it blocks cell division.

Detailed explanation-2: -Internal regulators-proteins that respond to events inside a cell. External regulators-proteins that respond to events outside the cell.-speed up or slow down the cell cycle. Growth factors-external regulators that stimulate the growth and division of cells.

Detailed explanation-3: -External factors include physical and chemical signals. Growth factors are proteins that stimulate cell division. – Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells. Two of the most important internal factors are kinases and cyclins.

Detailed explanation-4: -Internal regulators are special proteins that permit the cell cycle to continue only when certain conditions have been met inside the cell. For example mitosis can’t proceed unless the DNA has been copied. Thus it allows the cell cycle to proceed only when certain processes have happened inside the cell.

Detailed explanation-5: -External regulators are also proteins, but they react to stimuli from outside the cell. They direct cells to either speed or slow the cell cycle based upon outside conditions. For example, one protein reacts to molecules on the outside of a neighboring cell.