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Multiple Choice
Which of the following statements about signal receptors is true?
A
All signal receptors are enzymes that catalyze chemical reactions.
B
Signal receptors can be located on the cell surface or inside the cell.
C
Signal receptors only respond to electrical signals.
D
Signal receptors are only found in prokaryotic cells.
Verified step by step guidance
1
Step 1: Understand the role of signal receptors in biology. Signal receptors are specialized proteins that detect and respond to specific signals, such as chemical molecules, light, or mechanical stimuli, to initiate a cellular response.
Step 2: Clarify the location of signal receptors. Signal receptors can be found either on the cell surface (embedded in the plasma membrane) or inside the cell (such as in the cytoplasm or nucleus). This depends on the type of signal they are designed to detect. For example, hydrophilic signals typically bind to surface receptors, while hydrophobic signals like steroid hormones can pass through the membrane and bind to intracellular receptors.
Step 3: Evaluate the statement about signal receptors being enzymes. Not all signal receptors are enzymes. While some receptors, such as receptor tyrosine kinases, have enzymatic activity, many others, like G-protein-coupled receptors, do not directly catalyze chemical reactions.
Step 4: Address the statement about signal receptors responding to electrical signals. Signal receptors are not limited to electrical signals; they can respond to a variety of stimuli, including chemical signals (e.g., hormones), physical signals (e.g., light or pressure), and others.
Step 5: Examine the statement about signal receptors being exclusive to prokaryotic cells. Signal receptors are found in both prokaryotic and eukaryotic cells. In eukaryotic cells, they play a critical role in processes like cell communication and signal transduction.