Introduction to microbes Flashcards
the microbial world
4 major groups
- Virus’
- Bacteria
- Fungi
• Parasites
sizes of micro-organisms
smallest
- prions
- proteins
- mycoplasma
- mitochondria
- bacteria
- eukaryotic cells (yeast, protozoa, human cells)
- Worms
largest
prions are
self replicating proteins
- Some features of microbes
- No nucleic acid
- E.g. BSC (mad cow)
mitochondria
technically bacteria
endosymbiosis and mitochondria
mitochondria are the result of endocytosis of aerobic bacteria
virus’ require
a host tissue to replicate
structure of a virus
Nucleic acid (DNA or RNA) covered into a protein coat and envelop with glycolipids on the surface (recognition).
how can virus’ be classified
Baltimore classfication
a virus classification system that groups viruses into families, depending on their type of genome (DNA, RNA, single-stranded (ss), double-stranded (ds), etc..) and their method of replication.
virus’ can have ………. or……….. DNA
single stranded or double stranded DNA
Enveloped single stranded DNA
parovirus 19 (affects platelets and RBC)
non-enveloped double stranded Virus’
- Adenovirus
- BK virus
- Human papilloma virus (cervical cancer)
- JC virus
enveloped doubled stranded virus’
- Herpes
- Hep B
- Molluscum contagiousness
viral RNA can be…
single stranded (posiitive or negative strand)
double stranded
positive stranded RNA virus’
- Icosahedral or helical
- Enveloped
- HIV
- Hep C
- Rubella
- Encephalitis
- Yellow fever virus
- West Nile virus
negative stranded RNA virus’
- Helical
- Enveloped
- Ebola
- Lassa
- Marburg
- Measles
- Mumps
- Influenza
- Parainfluenza
- Respiratory syncytial virus
double stranded RNA virus’
- Icosahedral or helical
- Enveloped
- HIV (Double positive-sense strand)
- Hep C
the tree of life
the tree of life is a metaphor which expresses the idea that all life is related by common descent. it is divided into:
- Eubacteria
- Eukaryotes
- Archaebacteria
some bacteria are
obligate (replicate intracellularly e.g. mycobacterium tuberculosis)
bacteria often carry
plasmids
plasmids
- Carry virulence factors
- Antibiotic resistance (can be transferred between diff species)
bacterial shapes
coccus
bacillus (rod)
spirillus
arrangement of cocci
clusters- staph
chains- strep
Gram staining
Is a common technique used to differentiate two large groups of bacteria based on their different cell wall constituents
outline gram staining
(fans can intimidate dad sadly)
- Fixation
- crysrtal violet
- iodine treatment
- decolorisation
- counter stain with safranin
gram positive
purple
gram negative
pink
linnaean taxonomy
genus and species
Staphylococcus aureus
mecically important bacteria (big list just read)
mechanisms of bacterial pathogenesis
- virulence factors
- toxins
bacterial virulence factors
o Host entry (e.g. polysaccharide capsule)
o Adherence to host cells (e.g. pili and fimbriae)
o Invasiveness (e.g. enzymes such as collagenase)
o Iron sequestration (siderophores)
o Exotoxins (e.g.diphtheria toxin)
- secreted
o Endotoxins (lipopolysaccharide)
- on surface recognised by host immune system
oxygen tolerance: aerobes
- can survive in the presence of oxygen
obligate aerobes
require oxygen for surivival
oxygen tolerance: anaerobes
can survive in absence of oxygen
obligate anaerobes
require oxygen-free environment for survival (unless able to form spores)
difference between prokaryotes and eukaryotes table
fungi can be divided into
yeast and moulds
yeasts
single-celled organisms e.g.
- Candida albicans
- Cryptococcus neoformans
- Pneumocystis jiroveci
moulds
multicellular
- Aspergillosis
- Dermatophytes (ringworm, athletes foot)
parasites can be divided into
protozoa and helminths
protozoa
single-celled
- Giardia lamblia
- Trypanosoma cruzi
Helminths
worms, multi-cellular
- Roundworms (e.g. enterobius vermicularis)
- Tapeworms (e.g. taenia saginata)
- Flukes (e.g. schistosoma mansoni)
