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Microbial Structure: Cytosol (Endospores (Size/Shape (central…
Microbial Structure: Cytosol
Ribosomes
composed of RNA and protein (60/40); large and small subunits
key player in translation; transcription and translation are coupled
different sized ribosomes in eukaryotes and prokaryotes allows the prok. ribosomes to be targets for antibiotics
Granules (inclusions)
storage bodies; excess of something the cell built, obtained nutrients
accumulate waste in a granule and release it all at once
examples
sugar granules: glycogen or starch storage
PolyB-hydroxybutyric acid (PHB): fat storage
Poly-meta-phosphate granules: phosphate storage --> Babes-Ernst granules in Corynebacterium
Endospores
Formation (sporulation)
under threatening environmental condtions
4-8 hourse; a long time compared to life cycle
starts like cell division; one side takes both cell walls; other layers are made around the one side which becomes the endospore
Size/Shape
central (metacentric)
terminal: on one end
subterminal: halfway between middle and end
swollen sporagium: spoon looking cell with spore in spoon
purpose it to protect: resistant to heating, freezing, drying, chemicals, radiation and antibiotics; can exist for many years
not in the majority of prokaryotic cells
can't reproduce
Bacillus spp and Clostridium spp
CORE: DNA, ribosomes, nutrients, enzymes; INNER MEMBRANE; GERM CELL WALL: peptidoglycan; CORTEX: thick layer of cross linked peptidoglycan; OUTER MEMBRANE; SPORE COAT: protein; EXOSPORIUM
Nucleoid
region of dense DNA
single circular chromosome; smaller than eukaryotic genome
origin of replication is often associated with cell membrane
length of chromosome is 1000x longer than the cell; use super coiling and scaffolding proteins to hold DNA together
Plasmids
Types
fertility plasmids: code for conjugation genes
virulence plasmids: code for genes important for pathogenicity; pathogenicity island (PAI) = genes are on same section of plasmid
col plasmids: code for antibiotics to eliminate competition; narrow target range
degradative plasmids: code for digestive enzymes
resistance plasmids: code for resistance to antibiotics and other toxins; can pass to other bacteria; transfer quickly
smaller circular pieces of DNA; contain non-essential genes, only kept if advantageous
classification based on characteristics; some are replicated more than others; different organisms have different plasmids
engineered plasmids: synthetically made or modified by scientists; how E. coli makes insulin