Single celled living organisms too small to be seen by the naked eye - viruses are not considered to be living
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What is a phylogenetic tree?
A diagram that represents evolutionary relationships among organisms - they are hypotheses, not definitve fact
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What is an infection?
A disease caused by microorganisms
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What are some examples of microorganisms?
Algae
Fungi
Bacteria
Viruses
Archaea
Protozoa
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What are some key features of bacterial cells?
No nucleus
Peptidoglycan cell wall
Gram positive or gram negative
Reproduce by binary fission
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How to tell whether bacteria is gram positive or negative from a gram stain?
Gram positive bacteria is purple with stain and gram positive is red
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What are some features of gram positive bacteria?
Has an inner most plasma membrane and thick cell wall
Antibiotics can penetrate one plasma membran easily
Infections easier to treat with antibiotics
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What are some features of gram negative bacteria?
Has an inner and outer plasma membrane and thinner cell wall
Antibiotics penetrate two plasma membranes less easily
Infections are harder to treat with antibiotics
Not cells (not living)
Nucleic acid core (DNA or RNA) surrounded by protein coat
Reproduce by microscopic parasites and invade host cells forcing them to make new viral DNA
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What is the innate immune system?
Non-specific defence system against all pathogens. Acts quickly within minutes to hours.
Anatomical barriers
Humoral immunity
Cell mediated immunity
B cells - memory and plasma and T cells - Helper and cytotoxic
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What is the role of antibodies?
Bind to and inactivate viruses and toxins - neutralising antibodies
Opsonization -Phagocytic cells grab the antibodies bound to the surface of foreign substance, for efficient phagocytosis
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What is microbiota?
All living organisms living in and on a human
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What is a Microbiome?
All genes of all these organisms
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What are virulence factors?
The components or structure of microorganisms that help in establishment of disease or infection
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What is antigenic drift?
Small changes in viral antigens due to point mutations in genes
Makes virus harder for adaptive immune system to recognise
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What is antigenic shift?
Major changes in viral antigens due to gene reassortment
Makes virus much harder for adaptive immune system to recognise
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What defines infection?
When the organism has reproduced inside the host
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What is pathogenicity?
When the organism intercacts with the host in a way that causes disease
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