Intro to microbiology Flashcards
1820-1910: ??? founded the science of medical statistics – demonstrating the impact of infectious disease on overcrowded populations
Florence Nightingale
??? demonstrated that microorganisms do not spontaneously generate. He suggested such germs could cause human illness and developed “Germ Theory”
Louis Pasteur
TRUE or FALS: swan neck flask with broth media inside boiled to sterilisation. Left for period of time, proved nothing spontaneously grew.
TRUE
Koch developed use of pure culture technique into a ??? which became critical for isolating and culturing bacteria. initially used gelatin
solid media
Koch isolated Vibrio cholerae and ??? using solid media
Tuberculosis bacillus
Koch postulate 1: The bacteria must be present in ???
every case of the disease.
Koch postulate 2: The bacteria must be isolated from the host with the disease and grown in ???
pure culture
Koch postulate 3: The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a ???
healthy susceptible host
Koch postulate 4: The bacteria must be ??? from the experimentally infected host.
recoverable
what couldn’t be determined by Koch’s postulates?
viruses
why can’t Koch postulates be applied to viruses?
son’t behave the same as bacteria, are much smaller
koch postulations limitations: can’t capture all relationships of bacteria with human hosts. For example, no ??? of infection for that particular microorganism e.g. leprosy. OR can’t be grown in pure culture in the lab
animal model
TRUE or FALSE: koch postulations limitations: doesn’t account for a harmless pathogen that becomes harmful in certain circumstances
TRUE
Harmless microorganisms may cause disease if:
- It has acquired extra virulence factors making it pathogenic.
- It gains access to deep tissues via trauma, surgery, an IV line, etc.
- It infects an ???
- Not all people infected by a bacteria may develop disease-subclinical infection is usually more common than clinically obvious infection.
immuno-compromised patient
Koch’s postulates have been modified over the years to
encompass:
Viruses
Obligate parasites
Slow viruses (viruses that cause symptoms in an infected host long
after the original infection and which progress slowly)
The microbial causation of cancer.
Molecular postulates relate to what is happening more at the ??? level. Criteria for determining whether a specific bacterial virulence factor
has a role in pathogenesis.
genetic level
molecular postulates 1: Identify gene (or gene product) responsible for virulence determinant
- Show gene present in strains of bacteria that cause the disease
- PRESENT or NOT PRESENT (?) in avirulent strains
Not present
molecular postulates 2:
- Disrupting the gene reduces OR increases (?) virulence
reduces
Molecular postulates 3:
Complementation with the gene restores ???
- Introduction of the cloned gene into avirulent strain restores ???
virulence
Molecular postulates 4 and 5: The gene is expressed in vivo. Specific immune response to gene product is ???
protective
Experimental demonstration of
Koch’s Molecular Postulates: using Prp, a multifunctional plasminogen binding M protein, is used. ??? replaces 2 amino acids which abolishes plasminogen binding activity. Complementation of the prp mutant is achieved by reverse complementation which results in stable complemented strains
for in vivo studies or where gene copy number is an issue. Plasminogen binding ability results reveals virulence determinant
Alanine
TRUE or FALSE: Microbiology today is more focused on the relationships among microorganisms and with their environment rather than specific microbes
TRUE
biofilms: One or more types microorganisms physically linked together and to the underlying surface by ???
substances they secrete
bacteria are usually found individually or in communities?
communities
biofilm environments are advantageous for microorganisms because ???
biofilms provide increased resistance to antibiotics and the immune system
EMERGING or REEMERGING (?): recently surfaced in the human population for the first time
emerging
EMERGING or REEMERGING (?): has existed in the past but has shown resurgance in resistant forms and expansion in geographic location
reemerging
HIV, SARS, Lyme disease, Bird Flu and Zika virus all of which have no cure are emerging or reemerging diseases?
emerging disease
Drug-resistant tuberculosis, cholera, dengue fever are emerging or reemerging diseases?
reemerging
what is the microbiome?
The entire collection of genes found in all of the microbes associated with a particular host. The ecosystem made up of microbes within and on the human body. That is, the collection of microbes that live in the human ”habitat.”
TRUE or FALSE: changes in microbiome cannot cause disease
FALSE
What are some limitations to microbiome treatment studies?
The trials are mainly pilot studies with small sample size.
The underlying mechanism for complete response required further investigation to optimise the experimental design and to personalise the treatment
Metagenomics is the study of ???
the total number of genomes in a sample
metagenomic estimates are conducted by PCR amplification of ??? or ??? rRNA genes because many bacterial Genera are non-culturable by known techniques
16S or 23S
bacterial cell walls have an ORGANISED or DISORGANISED structure?
organised
bacterial cell wall:
- Covers entire cell surface, serving as an exoskeleton
- Provides structural integrity
- Anchors cellular appendages
- Protects the cell from injury
- Maintains ??? and prevents ???
water balance and prevents cell
rupture
Bacteria are classified into two major groups: ???
Gram-positive or Gram-negative following staining
Gram stain results reflect the thickness of the ??? layer in the bacterial cell wall.
peptidoglycan
Gram-positive bacteria stain ??? whilst Gram-negative bacteria stain
???
purple/blue, pink.
Gram-positive bacteria have thick peptidoglycan cell walls containing ??? acid.
teichoic
Gram-negative bacteria have a 2-dimensional peptidoglycan layer
and NO teichoic acid. Outer membrane contains ???
separated from the cell membrane by the periplasmic space
porins
The ??? is a sticky layer of
polysaccharides secreted externally to the cell wall. It has two layers:
- Capsule: Thick, firmly bound layer.
- Slime layer: Diffuse, water-soluble
layer.
glycocalyx
What protects cells from the environment, allows them to attach to surfaces, and also helps pathogens evade immune system?
glycocalyx
Pili are short protein fibres extending from the surface of many gram- NEGATIVE or POSITIVE (?) bacteria
negative
Type I Pili: Contain adhesins that
attach cells to surfaces. Act as ??? in pathogenic bacteria.
virulence factor
Type IV pili: Provide ??? to cells.
twitching motility
Conjugation pili: Used to transfer
??? between cells.
genetic material
Prokaryotic flagella are very long corkscrew appendages extending from ??? at one or more points.
the cell surface
Bacterial flagella are used for locomotion and ???
Flagella differences are used to classify bacterial strains
chemotaxis (moving up or down chemical gradients).
Bacterial spores survive ???. Spores “germinate” to form vegetative cells eg. Bacillus anthracis
desiccation and heating
Vegetative cells usually are destroyed at 60C while spores require heating to ???
121C for 15 min.
??? are tiny infectious agents that are obligate intracellular parasites. They lack the machinery for generating energy/large molecules and need a host cell to replicate.
Viruses
Viruses have either a DNA or RNA
genome which can be ???
single- or double-stranded
The major components of viruses include:
- The genome which can be either single- or double-stranded DNA or RNA.
???
???
- Capsid (or core) which is the protein shell of the virus.
- Many animal viruses contain an envelope, which is made up of host cell membrane and viral proteins.
Bacteriophage (or coliphage) T4 infects E. coli. Many bacteriophage contain a tail structure, which is
used ???
like a syringe to inject the bacteriophage genome
into the host cell.
Eukaryote viruses are usually rod-shaped, oblong or round and DO or DO NOT (?) possess a “tail” structure
do not
Cultivation of Viruses can be performed in a primary cell culture where cells form a monolayer in a culture dish and ??? effects are noted. Viruses can also be identified by the formation of plaques—clear zones within the monolayer—and phage typing of the plaques, as specific strains create characteristic plaques.
cytopathic
