Question

lesson 2: the cell membrane
lesson goals

• i can model how cell membranes control what materials enter and leave a cell.
• i can relate the flow of materials across a cell membrane based on their concentrations.

lesson activities
□ connect to prior knowledge
□ exploration activity
□ reading and questions
□ videos (optional)
□ case study: researchers target cell membrane for cancer research
□ review questions
lesson vocabulary
the meaning of the words in bold found throughout the lesson can be found in the glossary at the end of
the module. make sure you read the definitions and refer back to the vocabulary words as you complete
the lesson.
engage
connect to prior knowledge
the function of the cell membrane is often compared to the function of a fence with a gate. explain this
analogy.

Explanation:

A fence serves as a boundary, safeguarding what's inside from external threats. Similarly, the cell membrane acts as a barrier, protecting the cell's internal environment. A gate in a fence allows controlled entry and exit of people or objects. The cell membrane has proteins (like channels and carriers) that enable selective transport of substances (such as ions, nutrients, and waste) across it, just as a gate controls movement through a fence.

Answer:

The cell membrane is like a fence as it forms a boundary around the cell, protecting its interior. It's like a fence with a gate because it has structures (proteins) that allow specific substances to enter or leave the cell, similar to how a gate controls what passes through a fence.