Why It Matters: Cell Membranes

Why describe and explain the structure and function of membranes?

Cystic fibrosis (CF) is a genetic disorder that primarily affects the lungs, as well as the pancreas, liver, and intestine. CF is characterized by abnormal transport of chloride and sodium across body tissues, leading to thick, viscous secretions. The hallmark symptoms of cystic fibrosis are salty tasting skin, poor growth, poor weight gain despite a normal food intake, accumulation of thick, sticky mucus, frequent chest infections, and coughing or shortness of breath. Symptoms often appear in infancy and childhood, such as bowel obstruction in newborn babies.

The most serious symptoms of CF are difficulty breathing and frequent lung infections. Often, lung transplantation is ultimately necessary as CF worsens. Other symptoms, including sinus infections, poor growth, and infertility affect other parts of the body.

Cystic fibrosis results from the malfunctioning of a single membrane transporter. How could this error in membrane transport result in such a disease?

Learning Outcomes

  • Describe the structure and function of membranes, especially the phospholipid bilayer
  • Distinguish between passive and active transport; explain how substances are directly transported across a membrane
  • Describe the primary mechanisms by which cells import and export macromolecules
  • Identify the main components of a signal transduction pathway