Cell Biology Overview

Cell Biology

• Definition: Study of cells, their physiological properties, structures, organelles, interactions, and functions.

• Cell Theory:

  • All living organisms are composed of cells.
  • The cell is the basic unit of life.
  • All cells arise from pre-existing cells.

• Types of Cells:

  • Prokaryotic Cells:

    • Lack a nucleus and membrane-bound organelles.
    • Example: Bacteria and Archaea.
    • Generally smaller and simpler than eukaryotic cells.

  • Eukaryotic Cells:

    • Have a nucleus and membrane-bound organelles.
    • Example: Animal cells, plant cells, fungi, and protists.
    • Larger and more complex.

• Cell Structure:

  • Plasma Membrane:

    • Semi-permeable barrier that controls the movement of substances in and out of the cell.

  • Nucleus:

    • Contains genetic material (DNA).
    • Controls cell activities and reproduction.

  • Cytoplasm:

    • Gel-like substance where cellular processes occur.
    • Contains organelles.

• Organelles:

  • Mitochondria:

    • Powerhouse of the cell; site of ATP (energy) production.

  • Ribosomes:

    • Sites of protein synthesis; can be free-floating or attached to the endoplasmic reticulum.

  • Endoplasmic Reticulum (ER):

    • Rough ER: Studded with ribosomes; involved in protein synthesis and processing.
    • Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.

  • Golgi Apparatus:

    • Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

  • Lysosomes:

    • Contain digestive enzymes to break down waste materials and cellular debris.

  • Chloroplasts (in plant cells):

    • Site of photosynthesis; contains chlorophyll.

• Cell Division:

  • Mitosis:

    • Process of cell division resulting in two identical daughter cells.

  • Meiosis:

    • Specialized division that produces gametes (sperm and egg cells); results in four genetically diverse cells.

• Cell Communication:

  • Cells communicate through signaling molecules and receptors.
  • Types of signaling: autocrine, paracrine, endocrine, and juxtacrine.

• Cell Transport:

  • Passive Transport: Movement of substances across the membrane without energy input (e.g., diffusion, osmosis).
  • Active Transport: Movement of substances against their concentration gradient, requiring energy (e.g., sodium-potassium pump).

• Cell Function:

  • Cells perform essential functions necessary for life, including metabolism, energy production, synthesis of biomolecules, and response to stimuli.

• Cell Specialization:

  • Cells can differentiate into specialized types to perform specific functions (e.g., muscle cells, nerve cells).

• Cell Cycle:

  • Phases: Interphase (G1, S, G2) and M Phase (mitosis and cytokinesis).
  • Regulation by checkpoints to ensure proper division and function.

Cell Biology Overview

• Study of cells encompasses physiological properties, structures, organelles, interactions, and functions.

Cell Theory

• Living organisms are made of cells; cells are the fundamental unit of life.
• Cells originate only from pre-existing cells.

Types of Cells

• Prokaryotic Cells:

  • Absence of nucleus and membrane-bound organelles.
  • Examples include Bacteria and Archaea; these cells are generally smaller and simpler.

• Eukaryotic Cells:

  • Presence of a nucleus and membrane-bound organelles.
  • Include Animal, Plant, Fungi, and Protist cells; these cells are larger and more complex.

Cell Structure

• Plasma Membrane:

  • Semi-permeable, regulates substance entry and exit.

• Nucleus:

  • Houses genetic material (DNA) and oversees cell activities and reproduction.

• Cytoplasm:

  • Gel-like medium for cellular processes and organelles.

Organelles

• Mitochondria:

  • Known as the powerhouse of the cell; ATP production site.

• Ribosomes:

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

• Endoplasmic Reticulum (ER):

  • Rough ER: Contains ribosomes; key in protein synthesis and processing.
  • Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxifying substances.

• Golgi Apparatus:

  • Modifies, sorts, and packages proteins and lipids for secretion or transport to other organelles.

• Lysosomes:

  • Contain enzymes for digestion of waste and cellular debris.

• Chloroplasts (in plant cells):

  • Location of photosynthesis and contain chlorophyll.

Cell Division

• Mitosis:

  • Process producing two identical daughter cells.

• Meiosis:

  • Specialized division forming gametes (sperm and egg cells); results in four genetically distinct cells.

Cell Communication

• Cells use signaling molecules and receptors for communication.
• Types of signaling include autocrine, paracrine, endocrine, and juxtacrine.

Cell Transport

• Passive Transport:

  • Substance movement across membranes without energy (e.g., diffusion, osmosis).

• Active Transport:

  • Movement against concentration gradients requiring energy (e.g., sodium-potassium pump).

Cell Function

• Cells are responsible for vital functions like metabolism, energy production, and biomolecule synthesis, along with responding to stimuli.

Cell Specialization

• Cells can differentiate into specialized types for specific functions, such as muscle or nerve cells.

Cell Cycle

• Includes phases of Interphase (G1, S, G2) and M Phase (mitosis and cytokinesis).
• Cell division regulation occurs through checkpoints to ensure orderly function and replication.