2016/17 -SAQ Flashcards
List four features of bacterial cells that distinguish them from eukaryotic cells
1.No membrane bound nucleus
2.Simper cell structure
3.Lack of membrane-bound organelles
4.Presence of cell wall
Absence of membrane bound nucleus
bacterial cells that distinguish them from eukaryotic cells
Lack true membrane bound nucleus
eukarotic cells: well defined nucleus enclosed by nuclear membrane
Simpler cell structure
bacterial cells that distinguish them from eukaryotic cells
Bacterial cell: relatively small, simpler cell structure
Eukaryotic: larger, more complex
Lack of membrane-bound organelles
bacterial cells that distinguish them from eukaryotic cells
Bacteria; lack this
Eukaryotic cells: Mitochondria, ER, Golgi Apparatus, lysosomes, peroxisomes
Presence of Cell Wall
bacterial cells that distinguish them from eukaryotic cells
Most bacterial cell: Peptidoglycan
Absent in eukaryotic cells except some fungi and algae
Major Components of biofilm extracellular matrix (ECM)
- Extracellular polymeric substances (EPS)
- Water
- Ions and mineral
- DNA
- Proteins
Extracelllarpolymeric substances
Major Components of biofilm extracellular matrix (ECM)
- complex mixture: polysaccharides, proteins, nucleic acids, and lipidsmake up the bulk of the ECM
- Structural integrity
- Protects the resident microbial community from external stresses
Water
Major Components of biofilm extracellular matrix (ECM)
A lot of water
Hydrated environment
For microbial growth and metabolic activity
Ions and Minerals
Major Components of biofilm extracellular matrix (ECM)
Calcium
Magnesium
Iron
- For microbial growth and metabolic activity
DNA
Major Components of biofilm extracellular matrix (ECM)
extracellular DNA (eDNA)
From lysed cells
Structural component
Source of nutrients and genetic material for th resident microbial community
Protein
Major Components of biofilm extracellular matrix (ECM)
Enzymes
Adhesins
Structural proteins
Diverse roles in biofilm formation, stability and function
Explain what thee Gram stain is used for?
Laboratory technique
Differentiates bacterial cellsinto 2 major groups based on cell wall structure
>Gram- positive
>Gram- negative
Gram stain- series of sequential steps
Application of crystal violet, iodine, alcohol, and safranin to bacterial cells
The Gram Stain
What components of the bacterial cell membrane determines the outcome of the staining procedure?
Outcome
- depends on chemical and physcial properties of bacterial cell wall
Physical
- thickness of peptidoglycan layer
Chemical
-Composition of peptidoglycan layer
Gram-positive bacteria
What components of the bacterial cell membrane determines the outcome of the staining procedure?
Thick layer of peptidoglycan
traps crystal violet-iodine complex
Cells appear purple/blye under light microscope
Gram-negative bacteria
What components of the bacterial cell membrane determines the outcome of the staining procedure?
Thinner layer of peptidoglycan
Surrounded by outer membrane that contains lipopolysacchararides (LPS)
>Negatively charged
Staining procedure
- Alcohol: dissolves outer membrane, removes crystal violet-iodine complex from the thin peptidoglycan layer> cell appear pink or red after adding safranin
Why is gram stain useful?
Identifying and classifying bacterial species
Determining antibiotic treatment
Gram negative bacteria generally more resistant to antibiotics
Why> presence of the outer membrane
What is the regressive theory?
Q: Key aspect of the regressive theory of virus origin?
- suggests virus evolved from free-living
- Cellular organisms lost their cellular machinery
- Became parasitic
- Viruses originated from intracellular parasites that lost abbility to replicate independently
- Became dependent on host cells for survival and reproduction
Key aspect of the regressive theory of virus origin?
- virus evolved from more complex cellular organisms
- Rather than emerging spontaneously from non-living materials
- Proposes that viruses evolved from once free-living cells that lost ability: metabolic functions
- became dependent on other cells for their survival and replication
- Hypothesis supported by large genome viruses: mimiviruses
- > complex replicaation cycles that resemblethose of cells
What do mamavirus, pandovirus and pithovirus have in common?
Giant viruses
1. Large genome size
2. Complex viral structure
3. Ability to infect ameoba
4. Controversial classification
5. Environmental reservoirs
Large genome size
What do mamavirus, pandovirus and pithovirus have in common?
Larger tha typical viruses
Mamavirus - 600 kilpbases(kb)
Pandoravirus -over 2.5 megabases
Complex viral structure
What do mamavirus, pandovirus and pithovirus have in common?
Caspids
Nucleocaspids
Multiple Layers of membranes
Ability to infect amoeba
What do mamavirus, pandovirus and pithovirus have in common?
Ameoba: single-celled eukaryoic organisms
Model hosts for studying viral infections
Controversial Classification
What do mamavirus, pandovirus and pithovirus have in common?
Matter of debate
Why>
Large size
Complex genomes
Scientists
-Argue resemble those of cellular organims more thantraditional viruses
Environmental reservoirs
What do mamavirus, pandovirus and pithovirus have in common?
Discovered in environmental samples in various locations around the world
Soil abd sedimant samples
Remote regions of melting permafrost
The 3 keys phases in the microsporidian life cycle?
- Infective spore stage
- Proliferative stage
- Sporogonial Stage
Infective spore stage
The 3 keys phases in the microsporidian life cycle?
- Start phase of microsporidian life cycle
- resistant to evironmental stresses
- Persist for long periods in environment
- Host organism ingest an infective spore
- > spore releases its content into the host cell
Proliferative stage
The 3 keys phases in the microsporidian life cycle?
- Replicates rapidly
- Divide into small multiple uninucleate cells = Meronts
- Meronts grow into surrounding tissues
Sporogonial stage
The 3 keys phases in the microsporidian life cycle?
Final stage
Meronts differentiate into spores
Spores released from host orgnism and can infect new hosts
Complete life cycle
How is microsporidian characterized?
The 3 keys phases in the microsporidian life cycle?
High degree of host specificity
Complex intracelllar parasitic strategy
Allows microsporidia to evade host immune defenses
Exploit host resources for own survival and reproduction
Three main reasons why urinary tract infectionsare morecommon in women
- Anatomy
- Hormones
- Sexual Activity
Anatomy
Q: Three main reasons why urinary tract infectionsare morecommon in women
Women
- shorter urethra
- easier for bacteria to travel up into the bladder
- causes infection
Urethra
- tube
- carries urbin from bladder to outside of the body
Hormones
Three main reasons why urinary tract infectionsare morecommon in women
Hormone changes during menstruationand menopause
alters pH balance of the vagina
atlers pH balance of the urinary tract
Favourable growth medium for bacteria
- >infection
Sexual Activity
Three main reasons why urinary tract infectionsare morecommon in women
Sexual activity introduce bacteria into UT
Increasing risk of infection
Sexually active women higher risk of developing UTIs than those who are not
Developing UTIs significance
Three main reasons why urinary tract infectionsare morecommon in women
Women more susceptible
Steps to UTIs
how> hydration, urinating frequenty and practising good hygeine
UTI suspected
- antibiotic treatment
- Prevent complications
- Prevent recurrence
List the receptor sites for the3 main mechanisms of adhesion used by uropathogenic Escherichia Coli (UPEC).
UPEC main mechanism of adhesion to attach to host cells in the urinary tract
1. Type 1 Pili
2. P Pili
3. S Pili
S Pili
List the receptor sites for the3 main mechanisms of adhesion used by uropathogenic Escherichia Coli (UPEC).
Adhesive structure used by UPEC
Bind to **siaylated glycoproteins **
Present of surface: bladder cells and urothelial cells in the urinary tract
Type 1 Pili
List the receptor sites for the3 main mechanisms of adhesion used by uropathogenic Escherichia Coli (UPEC).
UPEC express type 1 pili
hair-like structures on bacterial surface
binds to mannose residues on the host cell surface
Receptor site=Uroplakin Receptor
Present on surface of bladder cells
P Pili
List the receptor sites for the3 main mechanisms of adhesion used by uropathogenic Escherichia Coli (UPEC).
Type of adhesive structure expressed by UPEC
Binds to globoseries glycolipid receptor
Present on the surface of renal epihelial cells
Among other cells in urinary tract
List extremophiles
(People prefer hot expresso)
- Piezopholes
- Psychrophiles
- Halophiles
- Endoliths
What environmental conditions to Peizopholes adapt to?
High pressures
Bottom of oceans
Withstand extreme pressure and oter environmental factors that exist at these depths
What environmental conditions to Psychrophiles adapt to?
In very low temperatures
Polar regions
Cold temperatures
What environmental conditions to Halophiles adapt to?
Thrive in high salt environments
Salt flats
Salt lakes
What environmental conditions to endoliths adapt to?
Live inside rocks and other geological structures
Survive in harsh conditions
High temperatures
Low nutrients
Limited access to water and other resources
Name 2 important diseases of the oral cavity?
1.Dental Caries/tooth decay
2.Periodontitis
Causative pathogen of dental caries
Caused by interaction of acid-producing bacteria with carbohydrates in the diet
Streptococcus mutans
Ability produce acid and adhere to tooth surfaces
Causative pathogen of Periodontitis
Serious gum disease
Result in tooth loss and other health problems
Caused by complex microbial communty
Porphyromonas gingivalis
Tannerella forsythia
Treponema denticola
> ability to fom biofilms
> induce infammation in gum tissue
> leads to destruction of the periodontal ligament
> Leads to destruction of the bone surrounding the teeth
List 2 important mycobacterial pathogens
- Mycobacterium tuberculosis
- Mycobacterium leprae
Disease caused by mycobacterium tuberculosis
Causative agent: M.tuberculosis of tuberculosis
Serious respiratory disease
Fatal if untreated
Affects lungs
bones and NS
Disease caused by Mycobacterium leprae
Causative agent: M. leprae of leprosy
chronic infectious disease
Affects skin, peripheral nerves
Symptoms: skin lesions, nerve damage, muscle weakness
Curable with appropriate treatment
Name 4 opportunistic pathogen associated with cystic fibrosis
- Pseudomonas Aeruginos
- Staphylococcus aureus
- Burkholderia cepacia complex
- Aspergillus fumigatus
