Patients suffering from celiac disease must follow a gluten-free diet. This leads to malnutrition, cramping, and diarrhea. The immune response damages microvilli, and thus, afflicted individuals cannot absorb nutrients. People with celiac disease have an immune response to gluten, which is a protein found in wheat, barley, and rye. This is an excellent example of form matching the function of a structure. Such cells are typically found lining the small intestine, the organ that absorbs nutrients from digested food. This folding increases the surface area of the plasma membrane. The plasma membranes of cells that specialize in absorption are folded into fingerlike projections called microvilli (singular = microvillus). There are other components, such as cholesterol and carbohydrates, which can be found in the membrane in addition to phospholipids and protein. Other compounds move passively across the membrane.įigure 3.9 The plasma membrane is a phospholipid bilayer with embedded proteins. The plasma membrane regulates the passage of some substances, such as organic molecules, ions, and water, preventing the passage of some to maintain internal conditions, while actively bringing in or removing others. A phospholipid is a lipid molecule composed of two fatty acid chains, a glycerol backbone, and a phosphate group. Like prokaryotes, eukaryotic cells have a plasma membrane ( Figure 3.9) made up of a phospholipid bilayer with embedded proteins that separates the internal contents of the cell from its surrounding environment. Animal cells have lysosomes and centrosomes. What structures does a plant cell have that an animal cell does not have? What structures does an animal cell have that a plant cell does not have? Plant cells have plasmodesmata, a cell wall, a large central vacuole, chloroplasts, and plastids. Figure 3.8 (a) This figure shows a typical animal cell Figure 3.8 (b) This figures shows a typical plant cell.
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