Bacteria Classifications Flashcards
Cellular vs acellular
-Cellular has genetic info; replicates autonomously
E.g. Prokaryotes, Eukaryotes
-Acellular is able to do one/both
E.g. Viruses, prions
Eukaryotes vs Prokaryotes - num of cells
Eukaryotes - multicellular
E.g. fungi, protozoa, helminths
Prokaryotes - unicellular
E.g. bacteria
Gram stain purpose
Differentiate between gram +ve and gram -ve bacteria
Similarities in gram +ve and gram -ve (cell envelope)
- Contain innermost phospholipid bilayer
- Have cell wall
Differences in gram +ve and gram -ve (cell envelope)
- Cell wall thicker in gram +ve than gram -ve
- Extra layer of phospholipids above cell wall in gram -ve
- Gap (periplasm) between inner phospholipid bilayer and cell wall in gram -ve
Gram stain process
- Add crystal violet dye
- Add iodine dye
- Alcohol water wash
- Safranin as counterstain for red colour
Alcohol water wash effect on gram +ve and gram -ve bacteria
In gram +ve the dyes are retained but for gram -ve they are washed away
Periplasm can store beta lactamase (T/F)
True
Cell wall - bacteria - made up of
- Peptidoglycans – sugar backbone NAN, NAG
- Peptide side chains on sugar backbone
Gram -ve cell wall components
Porins - tubular; connects outside environment to periplasm
Murein lipoproteins - connects cell wall to outer membrane
LPS - Lipopolysaccharide - O lipids, core polysaccharide, Lipid A/endotoxin (embedded in outer membrane)
Endotoxins - present gram -ve’s, only present in one gram +ve — Listeria
Antibiotics do not travel through porins (T/F)
False
Porins can change to avoid antibiotics travelling through porins (T/F)
True
Gram +ve cell wall components
Lipotechoic acids- embedded in cell wall; regulates enzymes; can cause immune response
Gram +ve and -ve cell wall similarities
- Flagella – tail like; attached to a basal body for anchoring
- Pili/fimbriae – attach one bacteria to another/mucosal human structures (grappling hook)
Host immune response to bacteria
Bacteria are slippery - need something to stick out like pins
Antibodies and C3B (complement cascade) attached to bacteria – makes it easier for host immune system to destroy cells
-> They act as opsonins
Opsonin function
-allows macrophages to attach and consume cells
Bacteria possessing capsules
SHiN SkiS Streptococcus pneumoniae, Haemophilus influenza type B, Neisseria meningitidis, Salmonella, Klebseilla pneumoniae, group B strep.
Bacterial genome
- Bacterial chromosome – contains essential bacterial genes
- Plasmids - transfer factors to other bacteria
- Antibiotic resistance
- Toxins
- Code for virulence factors – pili, flagella
Bacteria transferring genes via transformation
These can all cause meningitis and has IgA-ase - degrades IgA
S pneumoniae
H influenza type B
Neisseria
IgA function
Prevents adherence of bacteria to surfaces
Conjugation process
F+ cell has the plasmid
F- lacks the conjugation gene
Hfr cell - chromosome is incorporated
Transposition process
Via Transposons - jumping genes
Can move from:
plasmid -> plasmid
plasmid -> chromosome
Transduction process
Via bacteriophages
Generalized transduction
Specialized transduction
- can transfer genes for antibiotic resistance to bacteria
Bacteria classified by cell wall properties
Wall absent
Thin, flexible walls present
Strong cell wall present (not necessarily thick wall, just inflexible)
