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Module 7 Lesson 2 Progress Check

Prompt

Read pgs. 169-172 then answer the "Check Your Progress" questions (p172 #1, 2, 4, 5) and submit your answers here.

Response

  1. Identify the molecules in the plasma membrane that provide basic membrane structure, cell identity, and membrane fluidity

    The primary structure of the plasma membrane is a lipid bilayer made up of phospholipids, which provide stability and a barrier between the inside and outside of the cell. Proteins embedded in the membrane contribute to cell identity through receptors and other signaling molecules. Cholesterol interspersed in the membrane maintains fluidity, ensuring the membrane is not too rigid or too fluid.

  2. Explain how the inside of a cell remains separate from its environment

    The plasma membrane acts as a selective barrier, allowing some substances to pass while excluding others. The lipid bilayer prevents water-soluble molecules from freely crossing, while protein channels and carriers facilitate the transport of specific molecules. This selective permeability ensures the cell's internal environment remains distinct from the external environment.

  3. Describe how the plasma membrane helps maintain homeostasis in a cell

    The plasma membrane helps maintain homeostasis by controlling the passage of substances into and out of the cell, ensuring that nutrients, ions, and waste products are properly regulated. Membrane proteins play key roles in signal transduction, allowing the cell to respond to changes in its environment. This regulation helps maintain the optimal internal conditions required for cell function.

  4. Explain what effect more cholesterol in the plasma membrane will have on the membrane

    Increasing the cholesterol content in the plasma membrane generally increases its rigidity and decreases its permeability to small, water-soluble molecules. While this can enhance membrane stability, too much cholesterol can negatively impact membrane fluidity and protein function. Maintaining an appropriate balance of cholesterol is crucial for optimal membrane function and, by extension, cell function.