Cells that line your intestines are known to possess a large number of membrane proteins that transport small molecules and ions across the plasma membrane. Which of the following cell structures would you expect to be required for this characteristic of the cells?
a. The endoplasmic reticulum
b. Peroxisomes
c. Lysosomes
d. The cell wall

Verified step by step guidance

1. Understand the role of membrane proteins: Membrane proteins are synthesized and processed in specific organelles within the cell. These proteins are essential for transporting small molecules and ions across the plasma membrane.
2. Analyze the function of the endoplasmic reticulum (ER): The ER, particularly the rough ER, is responsible for the synthesis of membrane-bound and secretory proteins. It is equipped with ribosomes that facilitate protein production.
3. Evaluate the role of peroxisomes: Peroxisomes are involved in the breakdown of fatty acids and detoxification of harmful substances. They are not directly involved in the synthesis or transport of membrane proteins.
4. Consider the function of lysosomes: Lysosomes are responsible for breaking down macromolecules and cellular waste. They do not play a role in the synthesis or transport of membrane proteins.
5. Assess the relevance of the cell wall: The cell wall is a structural component found in plant cells, fungi, and some prokaryotes. It does not contribute to the synthesis or transport of membrane proteins. Based on this analysis, the endoplasmic reticulum is the most relevant structure for this characteristic of intestinal cells.

Key Concepts

Membrane Proteins

Membrane proteins are integral or peripheral proteins that reside within or on the surface of the cell membrane. They play crucial roles in transporting molecules and ions across the plasma membrane, facilitating communication and signaling between the cell and its environment. Their presence is essential for maintaining cellular homeostasis and enabling nutrient absorption in intestinal cells.

Endoplasmic Reticulum (ER)

The endoplasmic reticulum (ER) is a network of membranes involved in the synthesis and transport of proteins and lipids. The rough ER, studded with ribosomes, is particularly important for producing membrane proteins, including those that transport molecules across the plasma membrane. This organelle is vital for the proper functioning of cells that require extensive transport mechanisms, such as intestinal epithelial cells.

Cell Membrane Structure

The cell membrane, composed of a phospholipid bilayer with embedded proteins, serves as a selective barrier that regulates the entry and exit of substances. Its structure allows for the formation of specialized regions where transport proteins can facilitate the movement of ions and small molecules. Understanding the cell membrane's architecture is essential for grasping how intestinal cells manage nutrient absorption and ion transport.