Prokaryotic cells Flashcards
What’s an example of a prokaryote?
Bacteria
Are prokaryotes or eukaryotes smaller?
Prokaryotes
How much smaller are prokaryotes than eukaryotes?
Between 100-1000 times smaller
What do prokaryotes have that makes them differ from eukaryotes? (4)
- a cytoplasm that lacks membrane bound organelles
- ribosomes are structurally smaller (70S) compared to 80S in eukaryotic cells
- no nucleus (instead they have a single circular DNA molecule that is free in the cytoplasm and is not associated with proteins)
- a cell wall that contains murein (a glycoprotein)
What are structures that prokaryotes have that differentiate the species from others and act as a selective advantage?
- plasmid
- capsules
- flagellum
What are plasmids?
Small loops of DNA that are separate from the main circular DNA molecule.
What do plasmids contain?
Genes that can be passed between prokaryotes (eg. Genes for antibiotic resistance)
Are plasmids present in all prokaryotes?
No
What is a capsule?
A final outer layer (sometimes called the slime capsule) which helps to protect bacteria from drying out and from attack by cells of the immune system of the host organism.
Are capsules present in all prokaryotes?
No
What is a flagellum?
A long, hair like structure that rotates, enabling the prokaryote to move.
Do some prokaryotes have more than one flagellum?
Yes
Are flagella present in all prokaryotes?
No
What are the structures that are sometimes present in the prokaryotes?
Flagellum
Capsule
Infolding of cell surface membrane
Plasmid
Pili
What does the infolding of the cell surface membrane do?
May allow photosynthesis to carry out nitrogen fixation
What is the Pili for?
Attachment to other cells or surfaces; involved in sexual reproduction
What structures are always present in prokaryotes?
Cell wall
Cell surface membrane
Cytoplasm
Circular DNA
Ribosomes
