Question

A human pancreatic cell obtains O2 and necessary molecules such as glucose, as amino acids, and Cholesterol from its environment, and it releases CO2 as a waste product. In response to hormonal signals, the cell secretes digestive enzymes. It also regulates its ion concentrations by exchange with its environment. Based on what you have just learned about the structure and function of cellular membranes, write a short essay (100–150 words) that describes how such a cell accomplishes these interactions with its environment.

Answer 1

Cellular membranes or plasma membranes has many functions. Some of these include regulation of cellular transport, and responding to cellular signals or hormones.

Cellular Transport

The plasma membrane is made up of the phospholipid bilayer with embedded transmembrane proteins. This makes the cell membrane semi-permeable. Movements of substances depend on the composition of the molecules e.g. glucose and amino acids, as needed by the pancreatic cells. These are larger and uncharged molecules and can't pass freely through the membrane so they utilize the transmembrane proteins via attaching to carrier proteins. This is called passive transport. On the other hand, in active transport, ATP is used to transfer molecules, like Hydrogen, from a low to high electrochemical gradient.

Other kinds of cellular transport are:

• Osmosis and diffusion
• Endocytosis
• Exocytosis

Cellular Signalling

The cell membrane is able to signal other neighboring cells by utilizing complex proteins. These proteins may take form as receptors or markers.

Membrane Receptors

They act as receivers of extracellular signals and spark intracellular processes. These receive signals from hormones, growth factors, etc.

Membrane Markers

These allow the cells to identify each other and respond if this cell is needs further development as in organ development, or a foreign body to the system.