Final answer:
Cell division and growth most likely occur when levels of growth factors are high. Growth factors stimulate the cell cycle, and their presence is needed for normal cell division. Aberrant cell growth, such as cancer, results from mutations in the DNA and the disruption of cell cycle regulation.The correct answer is d) When growth factor levels are high.
Step-by-step explanation:
You asked under what conditions normal cell division and growth will most likely occur. The correct answer is d) When growth factor levels are high.
Normal cell division and growth typically occur in an environment where there is an optimal level of growth factors. Growth factors are a group of proteins that stimulate cell division. They bind to cell-surface receptors and trigger cell signaling pathways that encourage cells to move through the cell cycle and divide. Cancer, on the other hand, results when there is a disruption in the regulation of the cell cycle, leading to uncontrollable cell division and potentially forming tumors. This usually happens due to mutations in the DNA, which affect genes that regulate the cell division process.
DNA repair
does not directly cause normal cell growth but it is a crucial mechanism that maintains the integrity of the genetic information, thereby preventing unregulated cell division as seen in cancer. Proteins like p53 help in repairing the DNA and in case they are damaged or inactivated, normal cell cycle progression may be affected, leading to possible tumor formation.
Densely packed cells
tend to stop dividing due to a phenomenon called contact inhibition, which prevents overgrowth. In addition, cells that do not pass the G₁ checkpoint of the cell cycle move into a quiescent state called G₀, which is a state outside of the cell cycle where cells are neither dividing nor preparing to divide.