Key Points: Gene Expression Timing & Plasma Membrane

Gene Expression Timing

• Expression is not random; it reflects which genes are active at the correct time.
• Temporal regulation of gene expression is essential for proper cellular function.

Plasma Membrane

• All living cells in multicellular organisms have a surrounding plasma membrane.
• The plasma membrane defines the cell boundary and mediates interactions with the external environment.

Boundary Role

• The plasma membrane separates the internal environment from the external environment; the skin is an example of this boundary in humans.