Cell Biology Basics

Cell Biology

Basics of Cell Theory

• All living organisms are composed of cells.
• Cells are the basic unit of structure and function in living things.
• New cells arise from existing cells.

Types of Cells

1. Prokaryotic Cells

   • Lack a nucleus.
   • Smaller and simpler (e.g., bacteria).
   • Genetic material is located in the nucleoid region.

2. Eukaryotic Cells

   • Have a nucleus.
   • Larger and more complex (e.g., plant and animal cells).
   • Contain membrane-bound organelles (e.g., mitochondria, endoplasmic reticulum).

Cell Structure and Function

• Cell Membrane

  • Semi-permeable barrier that controls movement in and out of the cell.
  • Composed of a phospholipid bilayer with embedded proteins.

• Nucleus

  • Contains genetic material (DNA).
  • Controls cellular activities and gene expression.

• Mitochondria

  • Powerhouse of the cell, site of ATP (energy) production.
  • Involved in cellular respiration.

• Ribosomes

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

• Endoplasmic Reticulum (ER)

  • Rough ER: Studded with ribosomes; synthesizes proteins.
  • Smooth ER: Lacks ribosomes; synthesizes lipids and detoxifies.

• Golgi Apparatus

  • Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.

• Lysosomes

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

• Cytoskeleton

  • Network of fibers providing structural support.
  • Involved in cell movement and transport within the cell.

Cell Division

• Mitosis

  • Division of the nucleus resulting in two identical daughter cells.
  • Phases: Prophase, Metaphase, Anaphase, Telophase.

• Cytokinesis

  • Division of the cytoplasm following mitosis, resulting in two separate cells.

• Meiosis

  • Specialized form of cell division that produces gametes (sperm and eggs).
  • Reduces chromosome number by half, introducing genetic diversity.

Cell Communication

• Cells communicate through chemical signals (e.g., hormones).
• Cell receptors bind to signaling molecules to initiate responses.
• Types of signaling:
  • Autocrine: Cell targets itself.
  • Paracrine: Cell targets nearby cells.
  • Endocrine: Signals travel through the bloodstream to distant cells.

Cellular Metabolism

• Metabolism consists of all chemical reactions within a cell.
• Catabolism: Breakdown of molecules to release energy.
• Anabolism: Synthesis of complex molecules for cellular functions.

Cellular Transport Mechanisms

• Passive Transport

  • Diffusion: Movement of molecules from high to low concentration.
  • Osmosis: Diffusion of water across a semi-permeable membrane.

• Active Transport

  • Requires energy (ATP) to move substances against their concentration gradient.
  • Includes pumps (e.g., sodium-potassium pump) and vesicular transport (endocytosis, exocytosis).

Basics of Cell Theory

• All living things are made up of cells
• The cell is the basic unit of life
• New cells come from pre-existing cells

Types of Cells

• Prokaryotic Cells
  • Lack a nucleus or membrane-bound organelles
  • Simpler and smaller
  • Example: Bacteria
• Eukaryotic Cells
  • Have a nucleus and membrane-bound organelles
  • More complex and larger
  • Example: Animal and plant cells

Cell Structure and Function

• Cell Membrane
  • Controls what goes in and out of a cell
  • Made of a phospholipid bilayer with embedded proteins
• Nucleus
  • Contains DNA, which is the cell's genetic material
  • Controls cellular activities and gene expression
• Mitochondria
  • The "powerhouse" of the cell, producing energy (ATP)
  • Involved in cellular respiration
• Ribosomes
  • Manufacture proteins for the cell
  • Can be free-floating in the cytoplasm or attached to the ER
• Endoplasmic Reticulum (ER)
  • Rough ER: Makes proteins, covered in ribosomes
  • Smooth ER: Makes lipids, detoxifies, and lacks ribosomes
• Golgi Apparatus
  • Processes and packages proteins and lipids
  • Prepares these molecules for secretion or use within the cell
• Lysosomes
  • Contain digestive enzymes to break down waste and cellular debris
• Cytoskeleton
  • Provides structural support for the cell
  • Involved in cell movement and transport within the cell

Cell Division

• Mitosis
  • Division of the nucleus resulting in two identical daughter cells
  • Four phases:
    • Prophase
    • Metaphase
    • Anaphase
    • Telophase
• Cytokinesis
  • Division of the cytoplasm after mitosis, leading to two separate cells
• Meiosis
  • Specialized cell division that produces gametes (sperm and eggs)
  • Reduces the chromosome number by half, introducing genetic diversity

Cell Communication

• Cells communicate through chemical signals like hormones
• Cell receptors bind to signaling molecules to trigger responses
• Types of signaling:
  • Autocrine: Cell targets itself
  • Paracrine: Cell targets nearby cells
  • Endocrine: Signals travel through the bloodstream to distant cells

Cellular Metabolism

• All chemical reactions occurring within a cell
• Catabolism: Breakdown of molecules to release energy
• Anabolism: Synthesis of complex molecules for cellular functions

Cellular Transport Mechanisms

• Passive Transport
  • Diffusion: Movement of molecules from high to low concentration
  • Osmosis: Movement of water across a semi-permeable membrane
• Active Transport
  • Requires energy (ATP) to move substances against their concentration gradient
  • Examples:
    • Pumps like the sodium-potassium pump
    • Vesicular transport (endocytosis, exocytosis)

Explore the fundamentals of cell biology with this quiz. Test your knowledge on cell theory, the differences between prokaryotic and eukaryotic cells, and the components of cell structure and function. Perfect for anyone looking to solidify their understanding of cellular concepts.