Flashcards in Infection - Microbes Deck (30)
What are the four main classifications of microbes that cause disease in humans?
Viruses, bacteria, fungi and parasites
What is a prion?
An infectious agent composed entirely of protein material which induces abnormal folding of specific normal cellular proteins called prion proteins
Put the following in order from smallest to largest:
Mitochondria, viruses, prions, mycoplasma/chlamydiae/rickettsiae, proteins
Put the following microorganisms in order from smallest to largest:
Eukaryotic cells, worms, bacteria, mitochondria
- eukaryotic cells
What are yeasts, protozoa and human cells all examples of?
What is the Baltimore classification of viruses?
A virus classification system that groups viruses into seven families, depending on their type of genome and method of replication.
What are the three types of DNA virus?
- single-stranded non-enveloped, eg. parvovirus 19
- double-stranded non-enveloped, eg. Adenovirus
- double-stranded enveloped, eg. herpes viruses
What is a viral envelope?
Envelopes derived from portions of the host cell membrane which also contain glycoproteins. The glycoproteins indenting and bind to receptor sites on the host membrane so that the envelopes can fuse.
Why are infections by enveloped viruses sometimes easier to treat?
The actual lipid bilayer of the viruses is often weaker and sensitive to destination, heat and detergents. They cannot survive for long outside the host environment.
What are the four types of RNA viruses?
1) Single-stranded, positive strand, icosahedral, non-enveloped, eg. norovirus
2) single-stranded, positive strand, icosahedral/helical, enveloped, eg. HIV
3) Single-stranded, negative strand, helical, enveloped, eg. Ebola
4) Double-stranded, icosahedral, non-enveloped, eg. Rotavirus
What is a bacteriophage?
A virus that can infect bacteria, meaning that DNA is transmitted between bacteria.
True or false - bacteria always contains RNA?
False - it's always DNA
Why are plasmids particularly important?
They can transfer genes for antibiotic resistance between bacteria
What is a bacterial capsule made of?
Polysaccharides, which do not stimulate the immune response and therefore protect the bacterium
What are circular shaped bacteria called?
What are spiral shaped bacteria called?
What are rod shaped bacteria called?
Bacillus, also sometimes 'rods'
What are the two arrangements of cocci?
Clusters and chains
What colour are gram positive and gram negative bacteria?
Gram positive - purple
Gram negative - red
Why are some organisms gram positive?
They have a large peptidoglycan wall which retains the gram stain. Gram negatives have a thinner peptidoglycan which doesn't stain as well
What is the differences between aerobic and anaerobic bacteria?
Aerobic bacteria can survive in the presence of oxygen, while anaerobes require oxygen free environment
What is an 'obligate' aerobe?
This requires oxygen to survive. An obligate anaerobe would be killed by even a small amount of oxygen
If microbes are named according to Linnaean taxonomy, how would they be named generally?
Genus + species, eg staphylococcus aureus
Give some examples of gram positive cocci
- Staphylococcus aureus
- alpha and beta haemolytic streptococci
- coagulase negative staph
- streptococcus pneumoniae
- enterococcus faecalis
Give some examples of gram positive bacilli
- listeria monocytogenes
- bacillus anthracis
- bacillus cereus
Give some examples of gram negative cocci
- neisseria meningitidis
- neisseria gonorrhoeae
- moraxella catarrhalis
- acinetobacter baumannii
Give some examples of gram negative bacilli
- escherichia coli
- klebsiella pneumoniae
- proteus species
- salmonella typhi
- pseudomonas aeruginosa
- haemophilus influenzae
What is the difference between endotoxins and exotoxins?
Exotoxins are deliberately released by bacteria to cause tissue damage, while endotoxins are components of the structure of the bacteria
What is the difference between yeasts and molds?
Yeasts are single-called, while molds are multicellular