2.1 - Cell Structure: Subcellular Components

Cellular Structure and Function

• Basic Cell Types: All life forms consist of cells that fall into two main categories:

  • Eukaryotic Cells: These cells contain their DNA within a nucleus and possess membrane-bound organelles.

  • Prokaryotic Cells: Unlike eukaryotes, these cells do not enclose their DNA in a nucleus and lack membrane-bound organelles.

• Common Cellular Components:

  • Cytosol: A jelly-like substance that supports and suspends subcellular components.

  • Ribosomes: Complexes composed of RNA and protein that are responsible for protein synthesis.

  • Plasma Membrane: A selectively permeable barrier that regulates the entry and exit of substances in and out of the cell.

• Organelles in Eukaryotic Cells:

  • Endoplasmic Reticulum (ER): A vast network of membranes continuous with the nucleus's membrane (nuclear envelope).

    • Smooth ER: Lacks ribosomes; synthesizes lipids and detoxifies toxins.

    • Rough ER: Covered with ribosomes; processes and packages proteins into vesicles for transport.

  • Golgi Complex: Consists of flattened membrane sacs that modify, sort, and package proteins. Acts as the cell's "warehouse," receiving vesicles from the ER and dispatching them to the plasma membrane or other cell locations.

  • Mitochondria: The powerhouse of the cell, where cellular respiration occurs, generating ATP. The inner membrane is folded into structures called cristae.

  • Lysosome: Contains hydrolytic enzymes for breaking down macromolecules.

  • Vacuole: A large vesicle with various functions, such as storing nutrients and regulating water content within the cell. In plant cells, the central vacuole supports growth and stores ions.

  • Chloroplasts: Present in plants and algae, these organelles conduct photosynthesis by converting solar energy into chemical energy.