Eukaryotic vs Prokaryotic Cells: Essential Review

Cell Classification

  • Two broad groups: eukaryotic cells vs prokaryotic cells
  • All living organisms fall into one of these cellular categories

Key Structural Differences

  • Nucleus:
    • Eukaryotes: true double-membrane nucleus containing DNA
    • Prokaryotes: no nucleus; DNA in nucleoid (open region)
  • Organelles (membrane-bound):
    • Present in eukaryotes (mitochondria, rough/smooth ER, Golgi, chloroplasts in plants)
    • Absent in prokaryotes
  • Ribosomes:
    • Both have them; eukaryotic ribosomes are larger, membrane-bound
  • DNA organization:
    • Eukaryotes: multiple, tightly packed chromosomes
    • Prokaryotes: single circular loop of stable chromosomal DNA

Size & Complexity

  • Eukaryotic cells generally larger
  • Prokaryotic cells smaller with higher surface-area : volume ratio \Rightarrow higher metabolic & growth rates, shorter generation times

Organismal Level

  • Eukaryotes: animals, plants, fungi, protozoa; mostly multicellular (exceptions: amoeba, paramecium, yeast)
  • Prokaryotes: bacteria, archaea; always unicellular

Reproduction

  • Eukaryotes: primarily sexual reproduction \Rightarrow genetic recombination
  • Prokaryotes: asexual binary fission \Rightarrow clonal offspring

Shared Features

  • Cell (plasma) membrane of phospholipids & proteins; selective barrier
  • Cytoplasm / cytosol: site of metabolic reactions (e.g., protein synthesis)
  • Ribosomes (protein synthesis)
  • DNA as hereditary material regulating cell functions