Prokaryotic and Eukaryotic Cells
Table of Contents
Endosymbiont Theory
- many scientists theorize that eukaryotes evolved from prokaryote ancestors.
- in 1981, Lynn Margulis popularized the "endosymbiont theory".
- "Endo" - inside
- "Symbiont" - friend
How it works?
- a prokaryote ancestor "eats" a smaller prokaryote
- the smaller prokaryote evolves a way to avoid being digested, and lives inside its new "host" cell kind of like a pet.
- the small prokaryotes that can do photosynthesis evolve into chloroplasts, and "pay" their host with glucose.
- The smaller prokaryotes that can do aerobic respiration evolve into mitochondria, and convert the glucose into energy the cell can use.
- Both the host and the symbiont benefit from the relationship.
Differences
Prokaryotes
- Organelles lack a membrane.
- Ribosomes are the only organelles.
- Genetic material floats in the Cytoplasm (DNA and RNA).
- Circular DNA
- Unicellular
- Cells are smaller in size.
- Has larger number of organisms.
- Appeared 4 billion years ago.
Eukaryotes
- Organelles covered by a membrane.
- Multiple organelles including ribosomes.
- Membrane covered genetic material.
- Linear DNA
- May be multicellular or unicellular.
- Cells are laregr in size.
- Has smaller number of organisms.
- Appeared 1 billion years ago.
Similarities
- Both types of cells have Plasma/Cell Membrane (outer covering of the cell)
- Both types of cells have Ribosomes
- Both types of cells have DNA
- Both types of cells have a liquid environment known as the Cytoplasm.