Question

Which of the following is a function of proteins in the plasma membrane?

Choose one or more:
-allow specific ions to cross the plasma membrane, thereby controlling its electrical properties
-serve as anchors to attach the cell to the extracellular matrix
-transmit extracellular signals to the cell interior
-generate the energy required for lipids to diffuse within the membrane
-transport molecules across the membrane

Answer 1

Proteins in the plasma membrane have several functions including allowing specific ions to cross, serving as anchors, transmitting signals, and transporting molecules.

Step-by-step explanation:

Proteins in the plasma membrane serve several functions:

1. They allow specific ions to cross the plasma membrane, thereby controlling its electrical properties. For example, gated channels for sodium, potassium, and calcium in their membranes open and close to facilitate electrical transmission along nerve cells or muscle contraction.
2. They serve as anchors to attach the cell to the extracellular matrix, providing structural support and stability.
3. They transmit extracellular signals to the cell interior. Complex, integral proteins known as receptors receive extracellular inputs and activate intracellular processes when their effectors are bound.
4. They transport molecules across the membrane. Carrier proteins are embedded in the plasma membrane and bind substances, triggering a change in shape that moves the bound molecule from the outside to the interior of the cell.