Prokaryotic Flashcards
How big are prokaryotic cells
Much smaller than eukaryotic cells ( between 100-1000x smaller)
How do prokaryotes differ from eukaryotes (present in all bacteria)
- A cytoplasm that lacks membrane-bound organelles
- Ribosomes are structurally smaller (70 S) compared to 80 S in eukaryotes. Not attached to any membrane
- No nucleus so instead have a single circular DNA molecule
- Cell wall made from murein (a glycoprotein)
Plasmids
- Plasmids are small loops of DNA that contain a few genes that can be passed between prokaryotes (e.g. genes forantibiotic resistance). Passed through pili during conjugation.
Additional features of a prokaryote not present in all bacteria
Plasmids
Capsule
Flagellum
Capsule
Final outer layer that protect bacteria from drying out and from attack by cells of the immune system of the host organism- creates issues for antibiotics
Flagellum -additional features
Long, tail like structures that rotate enabling the prokaryote to move. Attached to a cell by a protein motor called dynein
Why do prokaryotes not have mitochondria
Because prokaryotes have no membrane-bound organelles.
Instead have mesosomes which are in-folding’s of the cell membrane that provide a large surface area for the attachment of enzymes involved in respiration
Viruses
Non living cells relatively simple in structure. Much smaller than prokaryotic cells (between 20 and 300nm in diam)
What do viruses structurally have
A nucleic acid core (their genomes are either DNA or RNA, and can be single or double-stranded)
A protein coat called a capsid
Some have an outer layer called an envelope formed usually from the membrane-phospholipids of a cell they were made in
Why is a virus parasitic
It can only reproduce by infecting living cells and using their ribosomes to produce new viral particles
