Final 3

Cell Types

  • Prokaryotic Cells

    • Lack a nucleus.

    • Do not contain membrane-bound organelles.

  • Eukaryotic Cells

    • Have a distinct nucleus.

    • Contain membrane-bound organelles.

Cell Membrane

  • Composition: Primarily composed of a phospholipid bilayer.

Channels in the Cell Membrane

  • Types of Channels:

    • Protein channels facilitate the movement of ions and molecules across the membrane.

    • They are selectively permeable, allowing only certain substances to pass through.

Phospholipid Structure

  • Regions of a Phospholipid:

    • Hydrophilic (water-attracting) head.

    • Hydrophobic (water-repelling) tails.

  • Functionality: The amphipathic nature of phospholipids allows them to form a bilayer, creating a barrier between the internal cell environment and external surroundings.

Lipid Bilayer Parts

  • Two Parts:

    • Hydrophilic Heads: Face outward towards the water inside and outside of the cell.

    • Hydrophobic Tails: Face inward, shielded from water.

Selective Permeability

  • Definition: The property of the cell membrane that allows certain molecules to pass through while restricting others.

Major Cell Structures (Organelles)

  • Nucleus: Contains genetic material (DNA); controls cell activities.

  • Mitochondria: Powerhouse of the cell; responsible for cellular respiration and energy (ATP) production.

  • Lysosomes: Contains digestive enzymes; breaks down waste materials and cellular debris.

  • Centrioles: Involved in cell division; helps organize the mitotic spindle.

  • Ribosomes: Sites of protein synthesis; can be free in cytoplasm or attached to the endoplasmic reticulum.

  • Endoplasmic Reticulum:

    • Rough ER: Studded with ribosomes; involved in protein synthesis.

    • Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.

  • Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or delivery to organelles.

  • Chloroplasts: Sites of photosynthesis in plant cells; converts sunlight into chemical energy (glucose).

  • Vacuoles and Vesicles: Storage and transport structures within the cell.