Reintro to Microbiology Flashcards
Name the major types of microorganisms
- Eukaryotic - protazoa and fungi
- Fungi
- Bacteria - prokaryotes
- Viruses
- Prions - infectious proteins
Protozoa features?
Unicellular eukaryotes 2-100μm Many are free living e.g. Malaria Often affect the immunocompromised Mainly a threat in developing countries
Fungi features?
Eukaryotic organisms with a variety of forms
Commercially important- baking, brewing
External, rigid cell wall- containing chitin
Filamentous or yeast forms
Many are dimorphic = ability to have 2 lifestyles
e.g. Candida
Bacteria features?
Most numerous organisms
Adapted to inhabit almost all habitats
- Even those not based on sunlight- deep sea vents
Responsible for PLAGUE
Produce a range of toxins- virulence factors
Specialised cell walls
Prokaryotes - no internal membranous compartments
How to classify bac?
- Cellular form
- Cocci (1)
- Diplococci (2)
- Tetrads (4)
- Sarcina (4 behind 4)
- Streptococci (wiggly)
- Staphylococci (kite shape)
Baclli:
Branching
Extended irregular rods
Kidney bean
Corkscrew
Helical - Cell wall structure
- Gram positive - 1 membrane = fuzzy part is peptidoglycan layer = retains stain = purple
- Gram neg - 2 membranes and thin cell wall between the 2 = perioplasmic space = do not retain stain = pink/red stain
What is a peptidoglycan?
A polymer of N-acetyl muramic acid and N-acetyl glucosamine (NAG)
Crosslinked via AA pentapeptides and anchored to cell wall
What surface structures do bac have?
Flagellum = allows movement
Pili and fimbriae;
- Proteinaceous filamentous structures
- Used for attachment to host cells or surfaces
- Adhesins at the tip for host interaction
- Used for twitching motility
- Pseudomonas spp.
What are pathogens? Example?
Disease causing bac e.g. Vibrio cholera - cholera
What are opportunistic pathogens?
Commensals that sometimes cause disease e.g. MRSA, N.meningitis
Where are commensals located? How much is there?
Main mass in digestive tract
1kg mass in bac
What are commensals?
Unseen hordes - mainly harmless, colonise surfaces and mucosa
What makes mycobacteria different?
Have a normal membrane, peptidoglycan and mycolic acids = more resistant = unusual cell well
Features of mycobacterium spp? Example of a mycrobacterium?
Gram pos rods, unusual cell wall - mycolic acid
Impervious to gram staining
Zeen Ziehl-Neelson acid fast staining procedure; mycobacteria in red
E.g M. tuberculosis
M.leprae significance? E.g of mycobacterium
First bac clinically associated with a disease - leprosy
Treated with antibiotics
What causes chlamydia? Features? What does chlamydia cause?
Caused by C.trachomatis Unusual gram neg cell wall Unusual life cycle - elementary body facilitates spread, reticulate body (intracellular replication) STI Urethral and vaginal infec Conjunctivitis Infertility and ectopic pregnancies Asymptomatic carriage important in spread - symptoms not obvious
Examples of diseases as a carrier state?
Gonnorhoea, chlamydia
What causes typhoid fever? Effects of this?
Salmonella typhi
Microorganisms remain in gall bladder and excreted in faeces when cured of typhoid fever = spread
Virus features?
Obligate intracellular parasites
Causes HIV
Unable to reproduce without host factors
Viral genome uses host to encode viral proteins
Outline the basic viral structure
Nucleic acid encapsulated by proteinaceous capsid
Varying shape and symmetry
Some further coated with lipid coat - enveloped e.g. HIV
What is viral latency?
What is retroviral replication?
Infec does not result in lytic cycle
- Incorporation into genome
- Latent infec of host cell away from site of infec
Retroviral replication;
- mRNA does reverse transcription forming DNA - incorporates into genome of hose = replicates e.g. HIV
Why is the lytic life style of viruses?
Virus internalised, host cell makes many copies of virus = released from cell
What can latent infections do?
Can re-activate e.g. due to stress
What do bacteriophages do? (is a virus)
Attack and kill bacteria - live in mouth
Prion features?
Not truly a microorganism but is an infectious agent
Heat resistant, filterable, stick to instruments
Can be detected in tonsils but not outside lymphatics
e.g. CJD
Aggregate into long fibres and amyloid plaques
Likely transmission via brain tissue
E.g KURU
What is Kuru? Symptoms and cause?
Fatal brain disorder
First symptoms = unsteady gut, tremors, slurred speech
Caused by cannibalism
