structure of prokaryote: unit 3 Chapter 12
Prokaryote structure
- Single celled with no membrane bound organelles
- Usually single chromosome
- Circular DNA in nucleoid
- Cell wall - protective layer - determines the shape
- Cocci, bacilli, and spirilli
- Other structures
- Capsule - outside of cell wall-protection-pathogens
- flagella -locomotion
- Pili (pius singular) - attachment to surfaces (HGT)
- Plasmids (extra chromosomal DNA)
Most common bacterial shapes
Prokaryotic Membranes
- Thin lipid bilayer plasma membrane
- selectively permeable
- Archaea- replaced fatty acids (link glycerol) with isoprene
- Some lipid monolayers
Prokaryotic cell wall
- Outside membrane
- Withstands osmotic pressure
- bacteria - always include peptidoglycan
- Thick peptidoglycan: gram-positive
- Thin peptidoglycan + outer membrane : gram negative
- Archaea no peptidoglycan
- Pseudopeptidoglycan
- Polysaccharide
- Glycoprotein
- pure protein
Reproduction
- Rates vary - minutes to longer (mutation and resistance)
- Asexual - usually binary fission = clones
- No genetic recombination