wk1- Microbes in focus Flashcards
what is taxonomic classification
7 ranks which classify infectious agents more specifically (generic name down to sub species)
how to write different kinds of taxonomic classification (naming conventions)
generic name only- capitalized and italicized/ underlined
both genus and species name- capitalized genus and lower case species and both italicized/underlined
common name- lowercase roman font
family name- capitalized and italicized/underlined
examples of naming conventions for infectious agents (5)
genus and species names italicized (Staphylococcus aureus)
italicize generic name (Chlamydia)
Roman font (staphylococci)
genus and species names italicized (Bacillus cereus)
italicized family name (Enterobacteriaceae)
what are key characteristics of single celled prokaryotic microorganisms? 4
-single celled
-lack membrane-bound organelles
-diverse group of infectious agents
-differentiate between morphology, cellular composition, nutritional requirements, metabolic activity and genetic material
what is morphology
the appearance of bacterial cells (size/shape)
key components within a prokaryotic cell and what their function is? 10
-fimbriae: attaches cell to surfaces
-plasma membrane: maintains integrity of internal environment of cell
-cell wall: semi-rigid that provides structural integrity
-capsule: protection against drying and phagocytosis and aids in surface attachment
-flagellum: filaments attached to cell that rotate for cell movement
-plasmid: DNA fragments that can replicate independently
-nucleoid: contains the genetic material (DNA)
-pilus: short hairlike on the surface of cell that transfer genetic material between donor cells and recipient cells
-cytoplasm: intracellular environment
-ribosomes: site of protein synthesis, subunits are smaller in prokaryotic cells
growth requirements classification for bacteria include what
aerobic, lactose fermentation, substrate utilization, etc
cellular classifciation for bacteria include things like
gram positive or gram negative (cell wall composition of thick or thin)
morphological classification for bacteria include things like
naming of the cell
how to differentiate bacteria cells 3
- morphology shape and size
- cellular/ cell wall composition (gram positive, purple- a thick outer peptidoglycan layer and gram negative- pink- a thin peptidoglycan layer between 2 cell membranes
- growth requirements (physical, nutrient, metabolism)
main difference between prokaryotes and eukaryotes?
presence of membrane bound organelles in eukaryotes
how can eukaryotes differ? 3 and examples for each
-single celled (yeast and protozoa)
-muticellular (fungi)
-complex higher order organisms (helminths)
key characteristics of fungi (yeast 5/mould 5)
yeast:
-single celled
-oval/circular shaped
-replicate asexually (binary fission)
-form skin and mucous membranes (part of endogenous microbiota)- opportunistic infection
-require organic carbon source for growth (heterotrophic)
moulds/ filamentous fungi:
-multicellular filamentous fungi
-grow through terminal end of filament called hyphae to produce mycelium
-require organic carbon source for growth (heterotrophic)
-asexual spore production by mitotic division
-asexual reproduction
key characteristics of parasites -(helminth) 5
-worms (flatworms or roundworms)
-multicellular parasites
-require more than one host throughout life cycle
-definitive host- harbors sexually mature adult form of worm
-intermediate host- supports the cyst and larval stages of development
-resistant cyst form
key characteristics of parasites (protozoa) 4
-single celled eukaryotes
-classified morphologically and by locomotive features
-caused by trophozoite
-can also form cysts to resist hostile environment exposure
describe key characteristics of nonliving infectious agents (viruses) 5
-composed of one type of nucleic acid (RNA or DNA) and protein coat surrounding (capsid)
-can have an outer envelope (lipids)
-small viral particles (virion)
-cannot replicate independently, hijack host cell pathways to replicate
-highly selective for cell type and host infection (tropism)
-classified by the type of nucleic acid coding and shape
describe key characteristics of nonliving infectious agents (prions) 5
-composed only of protein
-host disease results in conformational change in protein structure located in brain
-leads to loss of neurological function and demise of host
-no antimicrobial treatments bc nonliving agent
-most resistant infectious agents to sterilisation because not metabolically active (different process for prions)
what to do to clean prions
effective cleaning using alkaline detergents (containing sodium hydroxide/sodium hypochlorite at 90–93°C) and extended steam sterilization (134°C for at least 18 minutes).
High-risk procedures for prion contamination of medical equipment include:
cerebral surgery
diagnosis pathways for infectious diseases 4
- isolation of the infectious agent from the host
- isolation of infectious agent biological components (toxins, enzymes) from the host
- a specific host immune response to components of the infectious agent
- host pathology and a relevant clinical history
when are direct or indirect isolation used?
direct isolation when infectious agents can be recovered from the patient sample and identified using phenotypic tests- cultured infections (bacteria, yeast, mould)
indirection isolation is used for genotypic identification of the agent.
specific host immune response is used when
to identify past or recent exposure to antigens via a PCR/serology (viruses)
possible outcomes of viral infections 4
acute lytic infection/ subclinical infection (symptoms of infection)
latent infection- remains dormant and may reactivate into different infections
carrier- remains infectious, low level shedding occurs
oncogenic- causes genetic changes, transformative
host pathology and clinical history is used when
using no invasive tests such as medical imaging to identify infectious agent
difference between antibody and antigen
antibody- a protein produced by the host to target antigens
antigen- foreign agent in body (bacteria, virus, etc)
