wk1- Microbes in focus

Question 1

what is taxonomic classification

Answer 1

7 ranks which classify infectious agents more specifically (generic name down to sub species)

Question 2

how to write different kinds of taxonomic classification (naming conventions)

Answer 2

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

Question 3

examples of naming conventions for infectious agents (5)

Answer 3

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)

Question 4

what are key characteristics of single celled prokaryotic microorganisms? 4

Answer 4

-single celled
-lack membrane-bound organelles
-diverse group of infectious agents
-differentiate between morphology, cellular composition, nutritional requirements, metabolic activity and genetic material

Question 5

what is morphology

Answer 5

the appearance of bacterial cells (size/shape)

Question 6

key components within a prokaryotic cell and what their function is? 10

Answer 6

-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

Question 7

growth requirements classification for bacteria include what

Answer 7

aerobic, lactose fermentation, substrate utilization, etc

Question 8

cellular classifciation for bacteria include things like

Answer 8

gram positive or gram negative (cell wall composition of thick or thin)

Question 9

morphological classification for bacteria include things like

Answer 9

naming of the cell

Question 10

how to differentiate bacteria cells 3

Answer 10

1. morphology shape and size
2. cellular/ cell wall composition (gram positive, purple- a thick outer peptidoglycan layer and gram negative- pink- a thin peptidoglycan layer between 2 cell membranes
3. growth requirements (physical, nutrient, metabolism)

Question 11

main difference between prokaryotes and eukaryotes?

Answer 11

presence of membrane bound organelles in eukaryotes

Question 12

how can eukaryotes differ? 3 and examples for each

Answer 12

-single celled (yeast and protozoa)
-muticellular (fungi)
-complex higher order organisms (helminths)

Question 13

key characteristics of fungi (yeast 5/mould 5)

Answer 13

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

Question 14

key characteristics of parasites -(helminth) 5

Answer 14

-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

Question 15

key characteristics of parasites (protozoa) 4

Answer 15

-single celled eukaryotes
-classified morphologically and by locomotive features
-caused by trophozoite
-can also form cysts to resist hostile environment exposure

Question 16

describe key characteristics of nonliving infectious agents (viruses) 5

Answer 16

-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

Question 17

describe key characteristics of nonliving infectious agents (prions) 5

Answer 17

-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)

Question 18

what to do to clean prions

Answer 18

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

Question 19

diagnosis pathways for infectious diseases 4

Answer 19

1. isolation of the infectious agent from the host
2. isolation of infectious agent biological components (toxins, enzymes) from the host
3. a specific host immune response to components of the infectious agent
4. host pathology and a relevant clinical history

Question 20

when are direct or indirect isolation used?

Answer 20

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.

Question 21

specific host immune response is used when

Answer 21

to identify past or recent exposure to antigens via a PCR/serology (viruses)

Question 22

possible outcomes of viral infections 4

Answer 22

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

Question 23

host pathology and clinical history is used when

Answer 23

using no invasive tests such as medical imaging to identify infectious agent

Question 24

difference between antibody and antigen

Answer 24

antibody- a protein produced by the host to target antigens
antigen- foreign agent in body (bacteria, virus, etc)

Question 25

serology is what

Answer 25

a diagnostic identification of antibodies in host serum

Question 26

gram positive bacteria

Answer 26

stain purple to show that they have a thick peptidoglycan layer and no outer lipid membrane

Question 27

gram negative bacteria

Answer 27

stain red pink to show they have a thin peptidoglycan layer and have an outer lipid membrane which makes it harder for antibiotics to eliminate them as they are more resistant with the outer lipid membrane