week 3 Flashcards
what are micro organisms
organisms that are too small to be seen with the naked eye
2 types of microrganisms + examples
acellular - pirons / viruses
cellular - prokaryotic / eukaryotic
What type of microorganisms are classified as acellular?
Those unable to replicate on their own.
State 3 differences between a prokaryotic cell and a eukaryotic cell
Prokaryotic cells have no nucleus whereas eukaryotic cells do have a nucleus.
Prokaryotic cells have a single circular chromosome whereas eukaryotic cells have multiple linear chromosomes.
Prokaryotic cells have a plasmid where as eukaryotic cells have no plasmid
Prokaryotic cells have no membrane bound organelles whereas eukaryotic cells do have membrane bound organelles.
viruses
- not living
- not eukaryotic or prokaryotic
- can not carry out metabolic reactions on their own (need a host cell)
viruses - structure
1) naked
- nucleic acid enclosed in a protein coat (capsid)
2) enveloped
- have an additional outer layer
What is normal microflora?
organisms that live on or in the body but do not cause disease
What is the advantage of a virus being enveloped?
Helps adherence
What is an advantage of naked viruses?
More resistant to the environment
What are the three functions of viral capsid proteins?
- antigenic properties
- helps with attachment
- protects the nucleic acid against inactivation
Why do viruses need a host cell?
The don’t have the DNA to replicate
viral repication
- adsorption
- attachment of viral capsid on receptor site of host - penetration
- virus enters cell via direct penetration, membrane fusion and phagocytosis - uncoating
- capsid is removed so nucleic acid can be released - synthesis
- copying of the nucleic acid - assembly
- nucleic acid and capsid is assembled. The DNA goes to nucleus and the RNA to cytoplasm - release
- naked viruses = released from host cell resulting in cell lysis and death
- enveloped viruses = bud out through cell membrane acquiring their envelope which has been modified by the insertion of viral glycoprotiens
List 5 ways a virus can be transmitted
airborne, faecal-oral, bodily fluids, vectors, foetal and neonatal
What is a vector?
Mosquito
Which human based diseases are caused by viruses?
Glandular Fever, HIV, Chicken Pox, Hep and Herpes
latent viral infections
remain dormant in some host cells and can become reactivated later
chronic viral infections
virus remains in host cells - gives rise to continuous low level of viral production and shedding (carrier state)
oncogenic viruses
cause tumors
Why are antibiotics useless in fighting viral diseases?
viruses have a protective protein that antibiotics can’t attack
treatment of viruses
1) vaccines
2) antiviral medications
Where in the body does HSV type 2 infect?
usually genitals
occasionaly around skin of mouth
Where in the body does HSV type 1 infect?
usually around skin around mouth
occasionally genitals
What is vertical transmission?
mother to child
What is the transmission route for HPV?
direct contact
HPV infects …..
the skin and mucus membrane
What are the major properties of bacterial cells?
cell membrane and cell wall
What colour do gram positive cells stain?
purple
What colour do gram negative cells stain?
pink
What is different about gram negative bacteria?
second lipid membrane made from lipopolysaccharides and lipoproteins
How is the nucleic acid of bacteria contained within a cell?
plasmids
What is the role of flagella?
Move in a watery environment
What are pili used for?
transfer of DNA during conjugation
What is the role of fimbrae?
allows adherence to host cell
What is virulence?
the ability to cause disease
What is a slime layer?
glycoproteins and polysaccharides form biofilms on medical devices
Are endospores alive?
no but they are resistant to environment
What are exotoxins?
a toxin secreted into the environment where bacteria are growing
What are endotoxins?
a toxin that forms the outer membrane of gram negative bacteria and it is released when the cell dies
What are common forms of bacterial reproduction?
cell division
What is the usual habitat for gram positive bacteria?
skin
What is the usual habitat for gram negative bacteria?
fluids (water, mucous)
How does tuberculosis spread from person to person?
Aerosol Droplets
What does a Mantoux test determine?
tuberculosis
mad cow disease, kuru, sheep scrapie, fatal familial insomnia are examples of
piron diseases
Are prions microorganisms?
no, but they are infectious
How are prions different from other infectious agents?
they don’t replicate outside the body and the body can’t detect them as dangerous
What are the common symptoms of someone with prions disease?
damage to the brain tissue
What are the transmission routes for human prion disease?
human to human, animal to human
distinguish between eukaryotes and prokaryotes
eukaryotes are multicellular and prokaryotes are unicellular
How do normal microflora protect against infection?
produces antimicrobial substances to protect from external pathogens
