4.01 Eukaryotic Cells Part 1

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