Lecture 5- Virology And Mycology Flashcards
What are the origins of virology
Hieroglyph from Memphis, Egypt. Approximate 3700BC
Temple priest ruma.
Show polio in deformity of foot in hieroglyph
What disease can be seen on pharaoh Ramses V 1196BC
Smallpox- scarring on face
Pocking mark on skin
What did dimitri iwanowski do (1892)
Filtered diseased tobacco plant extracts
What are viruses
Sub microscopic Obligate intracellular parasites Assemble, not grow Lack essential apparatus for generation of energy and protein synthesis Entirely dependant on host cell function
What was the iwanowski experiment
Took mixture through elementary filters (using ceramic) containing bacteria and viruses. Ceramic can stop bacteria.
Assumed that filterable virus would get through the filter but bacteria stopped.
Abraised this virus only liquid very gently onto lead and it became diseased.
What did Edward Jenner
Pioneer of vaccinations
Noted milkmaids got cowpox but not small pox. Took pock off her hands and jab into a boy called fipps. Protected him against smallpox
What did martinus beijerinick do (1898)
Confirmed iwanowski data, said it was a soluble living germ ‘contagium vivium fluidium’. Believed nothing cellular could be this small so assumed it was a soluble component
Believed only in plants
What did loeffler discover (1898)
Foot and mouth. Even when in animals people still believed that it wouldn’t occur in humans. Until polio next year
Name two bacteriophage pioneers and the dates
Frederick twort (1915) Felix d'Herelle (1917)
How are the largest VIRUSES compared to bacteria in size
10x smaller
What are the 4 types of bacteria
Bacteriophage, envelope, naked, helical
What is common between the 4 viruses
All have central icosahedral virus pod.
Why do most viruses have icosahedral centre.
Comes back to coding capacity - genome small so only a few choices to create something. “Building blocks very similar so get same house”
How many triangular faces and corners are there in the icosahedral core
20 triangular faces
12 corners
What are the little balls that due to the trigonometry form the capsid
Capsomeres
Where is the nucleic acid in the helical viruses
Middle
What type of RNA strand is able to be translated into vital proteins by interacting with ribosomes
ONLY RNA +ve strand
Once the virus is bound the ribosome the replication is essentially the same as our own. True or false
True
Describe the overview of the viral lifestyle
Attachment
Endocytosis
Hijack machinery of cell to start making viral genome
Then particles need to be expressed. Tell cell to start assembling capsids to form viruses
Released viruses
Cells eventually just collapse and die.
The NAKED virus doesn’t go into the cell whilst it penetrates the cell. True or false
True
The envelope virus doesn’t enter the cell when virus is attached to the cell
False. The virus enters the host cell and viral envelope is removed. Capsid is then enzymatically removed.
What two types of methods can enveloped viruses do to enter the cell
Endocytosis - all gets in, bring in signatures on outside that day cell infected
Fusing ,signature stay outside
What happens to the host cell in naked viruses
The host cell deteriorates and virus is released
What happens to both enveloped and naked viruses when they are released.
Some viruses obtain their envelope from host cell membrane upon release (naked viruses). Others which obtain their envelope from the cell nucleus are released by exocytosis (envelope viruses)
Where are the receptors on the bacteriophage
End of pins of legs.
What is the specificity of binding between phage and bacteria called
Phage typing
Describe lytic phage replication
Pins dock onto bacterium
Contraction of middle part (act like a molecular syringe- poke holes in bacterium and inject viral genome into cytoplasm)
After they have self assembled, the cell dies and they are released.
Describe lysogenic phage replication
Doesn’t always cause lysis.
Phage bind to cellular receptors, inject genes.
Viral DNA integrates itself into host DNA so it’s called a “pro phage”
Bacteria gets ‘super powers’.
What is punctuated evolution
matter of a week a bug can from 0 to hero when prophage go into DNA as sometimes more goes in than out
Are naked viruses or envelope viruses affected by alcohol hand gel
Enveloped viruses - need a lipid
