Prokaryotic Cells Flashcards
What is a prokaryote?
A single celled organism without a nucleus which does not have membrane bound organelles.
What are the key features of a prokaryotic cell?
- Doesn’t have a nucleus
- Organelles are not membrane bound
- Includes all bacterial cells
What are plasmids?
Small rings of DNA found in prokaryotic cells which code for specific features e.g. antibiotic resistance. They can be shared between bacterial cells to pass on resistance.
How do prokaryotes reproduce?
Asexually, by binary fission, which is where the prokaryotic cell duplicates it’s genetic information and divides.
What features are unique to prokaryotes?
- Cell wall (different structure)
- Capsule
- Pili
- Mesosomes
- Flagellum (different structure)
How is a prokaryotic cell wall structured?
It is made from peptidoglycan (known as murein) which is a complex polymer formed by sugars and amino acids.
What is a capsule?
A protective slimy layer which helps the cell retain moisture and adhere to surfaces.
What are mesosomes?
Infolding of the cell’s inner membrane which contains the enzymes required for respiration.
What are pili?
Hair like structures that attach to other bacterial cells.
How is a prokaryotic flagellum structured?
They are thinner than eukaryotic flagellum and do not have a 9+2 arrangement. They are attached to a plasma membrane by a basal body and are rotated by a molecular motor which provides a whip like movement.
Chemiosmosis allows for rotation.
What is the difference between ribosomes in prokaryotic and eukaryotic cells?
Prokaryotic cell ribosomes are smaller (70s) and eukaryotic ribosomes are larger (80s).
How is DNA different in prokaryotic and eukaryotic cells?
Eukaryotic DNA is linear and prokaryotic DNA is circular. Eukaryotic DNA is also enclosed within a nuclues.
What is meant by endosymbiosis?
Endosymbiosis is the theory that mitochondria and chloroplasts were formerly free living bacteria (prokaryotes). The theory is that these prokaryotes were taken inside another cell as an endosymbiont.
What is an endosymbiont?
An organism that lives within another - prokaryotic endosymbionts such as chloroplasts and mitochondria led to the evolution of eukaryotic cells.
What evidence supports the endosymbiosis theory?
- Mitochondria contain mitochondrial DNA which allows them to reproduce
- Stroma in chloroplasts contain DNA
- Mitochondria and chloroplasts both have membranes
