Question

Extracellular (cell membrane) signal receptors:

a) Bind to intracellular proteins
b) Transport molecules across the membrane
c) Transmit signals across the cell membrane
d) Regulate mitochondrial functions

Answer 1

Extracellular (cell membrane) signal receptors are integral proteins that bind to ligands and transmit signals across the cell membrane, initiating intracellular responses.

Step-by-step explanation:

Extracellular (cell membrane) signal receptors, also known as transmembrane receptors, are integral proteins that perform the critical function of signal transduction. These receptors bind to external ligand molecules and convert an extracellular signal into an intracellular one without the ligand needing to enter the cell. Therefore, the correct answer is that extracellular signal receptors transmit signals across the cell membrane.

These receptors are essential for cellular communication, responding to various extracellular molecules such as hormones and growth factors. When these extracellular molecules bind to the receptors, it triggers a cascade of intracellular events leading to a response within the cell. This process is vital for many physiological responses, including the immune system's ability to recognize 'self' versus 'non-self,' tissue and organ development, and the regulation of gene transcription.