Differences Between Eukaryotes and Prokaryotes

You should remember the following differences between prokaryotes and eukaryotes.

Eukaryotes…

  • Have organelles
  • Replicate by Mitosis/Meiosis
  • Have both linear (in nucleus) and circular (in mitochondria and chloroplast) DNA
  • Are roughly between 1-100um (some can get a lot larger however)
  • Have histones and chromatin
  • Have the Na+/K+ pump
  • Use the Krebs cycle, electron transport chain in cellular respiration

Prokaryotes

  • Have no membrane bound organelles
  • Replicate via binary fission
  • Have circular DNA
  • Are roughly between 0.2-2um
  • Have nucleoid proteins
  • Have the H+ Pump (proton pump)
  • Can have capsules

Similarities Between Eukaryotes and Prokaryotes 

Of course, there are many things which eukaryotes and prokaryotes share with each other

Eukaryotes…

  • Have ribosomes (80s + 70s)
  • Have a cytoplasm
  • Have a plasma membrane
  • Have DNA/RNA
  • Can have Flagella
  • Have a cytoskeleton
  • Can have a cell wall
    • Plants: made from cellulose
    • Fungi: made from chitin
  • Perform glycolysis

Prokaryotes…

  • Have ribosomes (only 70s)
  • Have a cytoplasm
  • Have a plasma membrane 
  • Have DNA/RNA
  • Can have flagella
  • Have a cytoskeleton
  • Can have a cell wall: made from peptidoglycan
  • Perform glycolysis

What Counts as a Eukaryote?

In the IMAT you need to be able to identify a cell as a eukaryote or prokaryote. Eukaryotes come in 4 major kingdoms…

  1. Animals: Humans, mammals, reptiles, fish, sponges, crustaceans etc
  2. Plants: Trees, ferns, shrubs, mosses etc
  3. Fungi: Mushrooms, yeasts, moulds etc
  4. Protists: Amoebas, slime moulds, algae

Knowing what counts as a eukaryote will help you if the IMAT gives you a cell by name and asks certain questions about it. 

The Nucleus

We can separate the nucleus into a few components…

The Nucleolus

  • Contains: Protein, rRNA, DNA
  • Role: 80s ribosome synthesis

The Nuclear Envelope

  • Contains: Phospholipids, protein (nuclear pores)
  • Role: Separates nucleus from cytoplasm

The Nuclear Pores (on the nuclear envelope)

  • Contains: Protein
  • Role: Passage of certain molecules
    1. In: Proteins, Ions
    2. Out: Ribosomes (rRNA, Protein), mRNA, tRNA, Ions

Chromatin

  • Contains: DNA, Proteins (Histones)
    1. Euchromatin: Transcribable
    2. Heterochromatin: Non-transcribable
  • Role:  
    1. Packages DNA
    2. Gene Regulation