The general structure of bacteria
The uni-cellular organisms
Viruses – Herpes virus, HIV, influenza virus
The procaryotic organisms – Escherichia, Salmonella, Pseudomonas – Streptococcus, Staphylococcus, Neisseria
The eucaryotic organisms – Candida, Aspergillus, Trichophyton – Entamoeba, Giardia, Plasmodium, Balantidium
General structure of a bacteria
Electron micrography of a bacteria cell
The structure of an eucaryotic cell
Comparison of prokaryot og eucaryot cells Procaryote
Eucaryote
size
1-10µm
10-100 µm
Nuclear membrane
mangler
present
Chromosomes
single circular
several linear
Nucleosomes
lacking
attached to chromosomes
relatively small
relatively large
Mitochondria
lacking
present
Golgi apparat
lacking
present
Endoplasmatic reticulum
lacking
present
Ribosomes
Flageller
without microtubuli with microtubuli
Common structures bacteria cell Function
Kemisk opbygning
Flagel
movement
protein
Pili
attachment, protection
protein
F or sex pili
transfer DNA under conjugation
protein
Capsule
attachment to surfaces, pro- polysaccharides tection against phagocytosis
Cell wall
protect, give form, stability
Cytoplasmic membrane
permeabilitets barriere, transport, energy, enzymes
Ribosomes
make synthesis of proteins
RNA, protein
Inclusions
reservelager for næringsstoffer
carbohydrate, lipid, protein, salts
peptidoglycan
Chromosomes genetic material
DNA
Plasmids
DNA
extrachromosomal DNA
Flagella og pili hos en peritrik bevægelig bakterie
Flagel typer
Flagella of (a) Bacillus cerius, (b) Vibro cholerae and (c) Bacillus brevis stained with flagel staining
Sex-pili
Electron micrography of flagella in Salmonella
The function af pili/fimbriae in different bactaria No.
Function
E. coli (alm. pili) 100-200
attach til mucous epithelial cells in the intestinal tract
E. coli (F-pili)
1-4
transfer DNA during conjugation
N. gonorrhoeae
100-200
attach til mucous epithelial cells in the uro-genital tract
Streptococcus ? pyogenes (fimbriae and M-protein)
attach til mucous epithelial cells, protect against phagocytosis, antigen variability
Ps. aeruginosa
attach til mucous epithelial cells
10-20
Electron micrography of fimbriae and pili
Mucoid colonies produced by abundant capsular production
Cell surface of Gram-positive, Gram-negative and acid-fast bacilli
Peptido-glycan layer
Peptidoglycan monomer
Function of cytoplasmic membrane serve as – an osmotic and permeability barrier provide place for – transport system for specific substances – specific enzyme systems provide energi to the cell owing to – respiratory and photosyntetic electron transport systems synthesize cell wall components – peptidoglycan, lipids and proteins coordinate – the replication and separation af DNA – formation of septum and cell division provide chemotaxi
Bacillus cereus with endospore
Electron micrography of endospore
Difference between vegetative cell and endospore Vegetativ celle
Endospore
Surface
Gram-positive cell wall
thick spore layer and peptidoglycan wall
microscopic appearance
Non-refractive
refractive
Enzymes
present
lacking
Synthesis of macromolecules
present
lacking
Heat resistant
low
high
Resistance against low chemicals and acids
high
Resistance against radiation
low
high
Lysozyme
sensitive
resistant
Metyleneblåt farve sensitive
resistant
Different types og spores seen by light microscopy
