B2.3 Cell Specialization/ Types

Sep 24, 2024

Lecture Notes: B2.3 Cell Specialization

Key Concepts

  • Multicellular Organisms: Composed of different cell types, originating from a single zygote.
  • Zygote Formation: Result of male and female gametes fusion, undergoing mitosis to form undifferentiated stem cells.
  • Differentiation: Process by which cells become specialized in structure and function.

Differentiation Process

  • Gene Expression: Different patterns of genes being turned on/off lead to specialized cell functions.
    • Liver cells express only liver-specific genes while others are turned off.

Stem Cells Characteristics

  • Unlimited Division: Stem cells can divide endlessly.
  • Multipotency: Ability to differentiate into multiple cell types.
  • Stem Cell Niches: Locations where stem cells reside, such as bone marrow or liver, allowing regeneration and differentiation.

Potency Types

  • Totipotent: Can become any cell type (e.g., early embryonic cells).
  • Pluripotent: Can develop into many, but not all, cell types (e.g., inner cell mass of embryo).
  • Multipotent: Limited to specific cell types (e.g., bone marrow stem cells).

Cell Specialization and Size

  • Size and Shape: Related to function.
    • Sperm: Long and narrow for locomotion.
    • Eggs: Large and round.
    • Red Blood Cells: Small, with a dent for oxygen efficiency.
    • White Blood Cells: Grow when activated.
    • Motor Neurons: Large cell body and long axon.

Surface Area to Volume Ratio

  • Importance: Smaller cells have greater ratios, aiding material exchange and heat distribution.
  • Adaptations:
    • Stay Small: To maintain high surface area to volume ratio.
    • Shape Changes: Large cells may have unique shapes or membrane folds to increase ratio.

Practical Implications

  • In Labs: Stem cell niches can be recreated to grow stem cells outside the body.
  • Cell Size Limitations: Large cells have less surface area, impacting efficiency in nutrient exchange and heat distribution.
    • Cells adapt through size or shape to optimize surface area relative to volume.

These notes encapsulate the main topics covered in the lecture on cell specialization, providing a comprehensive overview of how different cell types develop from a single cell and the biological significance of cell size and structure.