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
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…
- Animals: Humans, mammals, reptiles, fish, sponges, crustaceans etc
- Plants: Trees, ferns, shrubs, mosses etc
- Fungi: Mushrooms, yeasts, moulds etc
- 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
- In: Proteins, Ions
- Out: Ribosomes (rRNA, Protein), mRNA, tRNA, Ions
Chromatin
- Contains: DNA, Proteins (Histones)
- Euchromatin: Transcribable
- Heterochromatin: Non-transcribable
- Role:
- Packages DNA
- Gene Regulation