Passage of animal cells through the cell cycle is regulated primarily by
A) the availability of nutrients.
B) intracellular second messengers.
C) extracellular growth factors.
D) direct cell surface interactions.

Question

Quizplus · Accepted Answer

Animal cells pass through the cell cycle primarily under the influence of extracellular growth factors. These factors bind to specific receptors on the cell surface, triggering intracellular signaling pathways that promote cell division. Nutrient availability and direct cell-cell interactions can also play a role in regulating the cell cycle, but they are not the primary regulators. Intracellular second messengers, such as cyclic AMP and calcium ions, can be involved in signaling pathways triggered by growth factors, but they are not the primary regulators in themselves.

Passage of Animal Cells Through the Cell Cycle Is Regulated