Lecture Notes: Prokaryotic and Eukaryotic Cells

Overview

• Types of Cells on Earth
  • Prokaryotic
  • Eukaryotic
• Historical Context
  • Prokaryotic cells are the most ancient and were the only form of life for billions of years.
  • Eukaryotic cells evolved from prokaryotic cells.

Characteristics of Prokaryotic Cells

• Size and Structure
  • Smaller than eukaryotic cells.
  • Simpler structure allows for quick and effective reproduction.
• Internal Structure
  • Lack a nucleus.
  • "Prokaryote" means "before nucleus."
  • No membrane-bound organelles.
  • Ribosomes scattered in cytoplasm.
  • DNA located in the nucleoid region (not membrane-bound).
• Cell Wall and Movement
  • Cell wall surrounds plasma membrane; composition varies between archaea and bacteria.
  • May have one or more flagella for movement.

Characteristics of Eukaryotic Cells

• Size and Complexity
  • Larger and more complex than prokaryotic cells.
• Internal Structure
  • Membrane-bound nucleus and organelles.
  • "Eukaryote" means "true nucleus."

Commonalities Between Prokaryotes and Eukaryotes

• Both have:
  • DNA as genetic material.
  • Ribosomes.
  • Cytoplasm.
  • Plasma membrane.

Differences Between Prokaryotes and Eukaryotes

• Origin and Complexity
  • Prokaryotes are older, smaller, and simpler.
  • Eukaryotes evolved later, are larger, and more complex.
• Cellular Structure
  • Prokaryotes lack nucleus and membrane-bound organelles.
  • Eukaryotes have a nucleus and organelles.
• Organism Type
  • Prokaryotes are always single-celled.
  • Eukaryotes can be single-celled or multicellular.
• DNA Organization
  • Prokaryotic DNA: single, circular chromosome.
  • Eukaryotic DNA: linear chromosomes.