Viruses Flashcards
What is botany?
It is the study of plants and plant products.
What is the smallest organism known and when was it discovered?
The Prion. 1983 - 1984
Classify in order of size: Virus, Viriods, Prion
Prion, Viriods, Virus
When did Linnaeus classify life into Plantae and Animalia
1776
When was the virus discovered?
1952, after the development of the electron microscope
Characteristics of prions
- They are misfolded proteins with the ability to transmit their misfolded shape onto normal variants of the same protein
- They contain proteins but lack nucleic acids
- They are responsible for a number of degenerative diseases in humans.
What are the diseases caused by prions?
- Scrapie
- Bovine Spongiform Encephalopathy (BSE) in cattle (commonly known as “mad cow disease”)
- Creutzfeldt–Jakob disease (CJD) in humans (Kuru)
Describe Viroids
- Small, highly-structured RNA genome-lacking protein capsules
- They are mainly RNA
- Preserved and transmitted to cells where they are replicated.
How many ribonucleotides do viroids have?
245 to 375
Diseases caused by viroids
Potato spindle tuber
Avocado sun blotch
Coconut cadang-cadang
What is a major difference between viruses and viroids?
Viroids introduce far less genetic information into host cells.
When did we get a hint of the existence of viruses?
1884 by Charles Chamberland with the incention of bacteria filters
What makes replication of viruses unique?
They lack cell structures or organelles/
What is the only characteristic of living things that viruses possess?
Reproduction, more accurately, replication
Which cell organelle do viruses use in replication?
Golgi apparatus of the host
How many types of nucleic acids can a virus have at a time?
Just one… DNA or RNA
Why are viruses referred to as obligate parasites? What else are they called?
They can only replicate inside living cells.
Absolute parasites
What is the difference between plant and animal viruses?
Plant - Only RNA
Animal - Only DNA
How do viruses infect their host?
- They take over the protein synthesis of the host and commands the host to produce more viral protein than host protein
- Once incorporated into the host system, it begins to kill or eradicate it.
What is replication?
It is the use the use of metabolic apparatus of the host to produce more of the virus.
General characteristics of viruses
- Cannot be seen with the naked eye
- Can only be seen with electron microscope. Their size is 20 to 300nm
- Cannot live in cell-free region
- Either DNA or RNA
- Contain naked chromosomes only found in living host
- No organelles
- No nuclear membrane, Prokaryotes
What are the criteria used for classifying viruses?
- Morphology
- Serology and electrophoresis
- Bichemistry
- Disease symptom
- Mode of transmission
What are the modes of transmission of viruses?
Mechanical
Insect or animal
How can we handle viral diseases?
- Vaccination
- Immunization
- Exclusion from infected person
Which is bigger? Plant viruses or bacteria?
Plant viruses are 50 times smaller than bacteria
What kind of viruses are the most-studied?
Bacteriophages. They attack bacteria. They are tagged T1 to T12 and T4 is the most widely structured.
How do viruses behave outside their host?
They form cysts (crystallized), becoming metabolically inactive.
What is the smallest unit of a virus?
Capsomere
What are the basic types of symmetries in viruses? Give examples…
- Helical (Tomato mosaic)
- Isometric (Adenovirus)
- Icosahedron (Polio or corona virus)
What are the shapes of viruses?
- Flexuous filamentous (Potato Virus X)
- Bullet-shaped (Tobacco mosaic virus)
- Rod-shaped virus (Alfafa mosaic virus)
- Flexous phage (Lettuce virus)
Give the shapes of these viruses:
- Potato Virus X
- Tobacco mosaic virus
- Alfafa mosaic virus
- Lettuce virus
- Potato Virus X - Flexuous filamentous
- Tobacco mosaic virus - Bullet-shaped
- Alfafa mosaic virus - Rod-shaped virus
- Lettuce virus - Flexous phage
Give the economic importance of viruses
- They cause incurable diseases
2. They are used for research to understand the nucleic acids, molecular explanation of protein synthesis
Why is T4 the most studied bacteriophage?
The bacteria on which it lives can be cultured in the lab while the virus on it is studied.
What are bacteriophages?
They are viruses that infect and replicate within bacteria and archaea
Bromo virus
Family - Bromoviridae
Description - Small icosahedral RNA virus
Examples - Bromo mosaic virus
Cauliflower mosaic virus
Family - Cauliflower mosaic viridae
Description - Double-stranded DNA, replicates in the cytoplasm
Examples - Cauliflower mosaic virus
Cucumovirus
Family - Cucumoviridae
Description - Naked icosahedral RNA virus
Examples - Cucumber mosaic virus
Luteovirus
Family - Luteoviridae
Description - Small isometric RNA genome
Examples - Barley yellow dwarf virus
Nepovirus
Family - Nepoviridae
Description - Polyhedral nematode-transmitted RNA virus
Examples - Tobacco ringspot virus
Potexvirus
Family - Potexviridae
Description - Flexuous rods, 480 - 590nm, RNA genome
Examples - Potato virus X
Potyvirus
Family - Potyviridae
Description - Flexuous rod-shaped helical single-stranded RNA
Examples - Potato virus Y
Tobamovirus
Family - Tobamoviridae
Description - Rod-shaped helical single-stranded RNA
Examples - Tobacco mosaic virus
Adenovirus
Example - Adenovirus
Arenavirus
Example - Lassa fever
Calcivirus
Example - Hepatitis E
Corona virus
Example - SARS virus
Rhadeovirus
Example - Rabies
Flavivirus
Example - Yellow Fever
Hepadnavirus
Example - Hepatitis B
Picorvirus
Example - Polio virus
Pox virus
Example - Small pox
Retrovirus
Example - HIV/AIDSq
Why can viruses not produce energy in the form of ATP?
Because they lack mitochondria and depend on their host.
