Final answer:
Intracellular signaling involves ligands binding to internal receptors inside cells, directly affecting DNA and protein production. Intercellular signaling involves communication between cells through the release of signal molecules and binding to cell surface receptors. They both regulate gene expression through the activation of transcription factors and binding to regulatory DNA sequences.
Step-by-step explanation:
Intracellular signaling refers to the process where ligands bind to internal receptors inside cells, allowing them to directly affect the cell's DNA and protein-producing machinery. This signal transduction pathway regulates gene expression by controlling the transcription of RNA or the translation of proteins. An example is the MAP kinase ERK pathway, which communicates a signal from a receptor on the cell surface to the nuclear DNA, regulating protein translation.
On the other hand, intercellular signaling involves the communication between cells through the release of signal molecules, such as hormones, in the extracellular environment. These molecules can bind to cell surface receptors, transducing their information into intracellular molecular signals. The activation of transcription factors in responding cells leads to the regulation of gene expression by binding to specific regulatory DNA sequences.