Cellular Structures and Functions

Cell Wall

  • Presence: Not found in all cells (e.g., animal cells).

  • Location: Outside the plasma membrane.

  • Composition: Varies depending on the organism; common components include cellulose (plants), chitin (fungi), and peptidoglycan (prokaryotes).

  • Functions: Provides shape, strength, protection, and support.

  • Plant Cell Walls: Have primary and secondary walls with pores called plasmodesmata.

Cell Membrane

  • Presence: Found in all prokaryotic and eukaryotic cells.

  • Composition: Primarily composed of proteins and lipids, with small amounts of carbohydrates.

  • Structure: Fluid-mosaic model, with a lipid bilayer and embedded proteins.

  • Functions:

    • Semi-permeable barrier: Controls the movement of molecules in and out of the cell.

    • Cell recognition and signaling: Senses chemical messages and identifies other cells.

    • Organelle boundaries: Encloses organelles in eukaryotic cells.

Note: The next section will discuss the cytoplasm and cytoskeleton.