Lecture 5- Virology And Mycology

Question 1

What are the origins of virology

Answer 1

Hieroglyph from Memphis, Egypt. Approximate 3700BC

Temple priest ruma.

Show polio in deformity of foot in hieroglyph

Question 2

What disease can be seen on pharaoh Ramses V 1196BC

Answer 2

Smallpox- scarring on face

Pocking mark on skin

Question 3

What did dimitri iwanowski do (1892)

Answer 3

Filtered diseased tobacco plant extracts

Question 4

What are viruses

Answer 4

Sub microscopic 
Obligate intracellular parasites 
Assemble, not grow 
Lack essential apparatus for generation of energy and protein synthesis 
Entirely dependant on host cell function

Question 5

What was the iwanowski experiment

Answer 5

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.

Question 6

What did Edward Jenner

Answer 6

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

Question 7

What did martinus beijerinick do (1898)

Answer 7

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

Question 8

What did loeffler discover (1898)

Answer 8

Foot and mouth. Even when in animals people still believed that it wouldn’t occur in humans. Until polio next year

Question 9

Name two bacteriophage pioneers and the dates

Answer 9

Frederick twort (1915)
Felix d'Herelle (1917)

Question 10

How are the largest VIRUSES compared to bacteria in size

Answer 10

10x smaller

Question 11

What are the 4 types of bacteria

Answer 11

Bacteriophage, envelope, naked, helical

Question 12

What is common between the 4 viruses

Answer 12

All have central icosahedral virus pod.

Question 13

Why do most viruses have icosahedral centre.

Answer 13

Comes back to coding capacity - genome small so only a few choices to create something. “Building blocks very similar so get same house”

Question 14

How many triangular faces and corners are there in the icosahedral core

Answer 14

20 triangular faces

12 corners

Question 15

What are the little balls that due to the trigonometry form the capsid

Answer 15

Capsomeres

Question 16

Where is the nucleic acid in the helical viruses

Answer 16

Middle

Question 17

What type of RNA strand is able to be translated into vital proteins by interacting with ribosomes

Answer 17

ONLY RNA +ve strand

Question 18

Once the virus is bound the ribosome the replication is essentially the same as our own. True or false

Answer 18

True

Question 19

Describe the overview of the viral lifestyle

Answer 19

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.

Question 20

The NAKED virus doesn’t go into the cell whilst it penetrates the cell. True or false

Answer 20

True

Question 21

The envelope virus doesn’t enter the cell when virus is attached to the cell

Answer 21

False. The virus enters the host cell and viral envelope is removed. Capsid is then enzymatically removed.

Question 22

What two types of methods can enveloped viruses do to enter the cell

Answer 22

Endocytosis - all gets in, bring in signatures on outside that day cell infected
Fusing ,signature stay outside

Question 23

What happens to the host cell in naked viruses

Answer 23

The host cell deteriorates and virus is released

Question 24

What happens to both enveloped and naked viruses when they are released.

Answer 24

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)

Question 25

Where are the receptors on the bacteriophage

Answer 25

End of pins of legs.

Question 26

What is the specificity of binding between phage and bacteria called

Answer 26

Phage typing

Question 27

Describe lytic phage replication

Answer 27

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.

Question 28

Describe lysogenic phage replication

Answer 28

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’.

Question 29

What is punctuated evolution

Answer 29

matter of a week a bug can from 0 to hero when prophage go into DNA as sometimes more goes in than out

Question 30

Are naked viruses or envelope viruses affected by alcohol hand gel

Answer 30

Enveloped viruses - need a lipid