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.

Explore the fundamental aspects of cell biology, including cell theory and the distinction between prokaryotic and eukaryotic cells. This quiz covers cellular structures such as the plasma membrane, nucleus, and cytoplasm, essential for understanding life at the cellular level.