The major difference between a cell that responds to a signal and one that does not use the presence of a
The correct answer and explanation is:
The major difference between a cell that responds to a signal and one that does not is the presence of specific receptors on or inside the cell.
Explanation:
Cells communicate and respond to signals through molecules such as hormones, neurotransmitters, or growth factors. These signaling molecules bind to receptors which are proteins usually located on the cell surface or sometimes inside the cell. For a cell to respond to a particular signal, it must have the correct receptor that recognizes and binds to that signal molecule.
Receptors are highly specific, meaning that only cells with the matching receptor for a given signal will be able to detect and respond to it. If a cell lacks the appropriate receptor, the signaling molecule cannot bind to it, so the cell will not respond.
When the signal molecule binds to its receptor, it triggers a chain of events inside the cell known as signal transduction. This process often involves activating enzymes, opening ion channels, or changing gene expression, ultimately leading to a cellular response such as movement, growth, or secretion.
For example, insulin signals muscle and fat cells to take up glucose by binding to insulin receptors. Cells without insulin receptors will not respond to insulin and will not increase glucose uptake.
In summary, the critical factor determining whether a cell responds to a signal is the presence or absence of specific receptors capable of recognizing and binding the signaling molecule. Without these receptors, the signal cannot be detected, and the cell remains unaffected by that signal. This mechanism allows the body to regulate complex functions selectively by controlling which cells respond to various signals.