Cell biologyLesson 1 of 4 in the course Structure and Function of Plasma Membranes

Plasma Membrane Structure, Components, and Fluidity

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

The plasma membrane defines a cell’s boundary and controls how it interacts with its environment. This lesson introduces the membrane’s major functions, the history of scientists’ models, and the components that make up a typical membrane.

The plasma membrane outlines a cell and separates its internal environment from the outside. It regulates the movement of substances: cells exclude some materials, take in others, and release still others in controlled amounts. This selective control helps the cell maintain conditions needed for life.

All flashcards

What does amphiphilic mean for a phospholipid?
It has both a water-attracting region and water-avoiding regions.
What is the glycocalyx?
The exterior carbohydrate chains of membrane glycoproteins and glycolipids.
How does cholesterol affect animal membrane fluidity?
It buffers fluidity by limiting tight packing in the cold and excessive movement in the heat.
What is a transmembrane protein?
An integral membrane protein that spans the entire lipid bilayer.
How can a membrane respond to a very small puncture?
Its mobile components can flow back together and self-seal.

Quiz questions

  1. What is a central role of the plasma membrane?Answer: It defines the cell boundary and regulates exchanges with the environment.
  2. In the fluid mosaic model, what does “mosaic” describe?Answer: A mixture of different kinds of membrane components.
  3. How does cholesterol help regulate animal membrane fluidity?Answer: It limits tight packing in the cold and excessive movement in the heat.
  4. What is characteristic of saturated fatty acid tails in phospholipids?Answer: They lack carbon–carbon double bonds and are relatively straight.
  5. About how many amino acids commonly make up a single-pass transmembrane segment?Answer: About 20–25 amino acids.

Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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