Bio. Classification Viruses Prions And Lichens Flashcards
What is the five kingdom classification of Whittaker missing?
Lichens, viruses, viroids, and prions
These organisms are not classified as living and have unique characteristics.
How are viruses classified in terms of living status?
Non-living
Viruses lack a cell structure and are considered non-cellular organisms.
What is the structure of viruses when outside a host cell?
Inert crystalline structure
Viruses do not exhibit life processes until they infect a host cell.
What term means venom or poisonous fluid in relation to viruses?
Virus
The term is derived from the Latin word for venom.
Who recognized microbes as the causative agents of mosaic disease in tobacco?
Dmitri Ivanowsky (1892)
He discovered that these microbes were smaller than bacteria.
What did M.W. Beijerinek name the new pathogen discovered in tobacco?
Contagium vivum fluidum
This translates to ‘infectious living fluid’.
What reveals that viruses can be crystallized?
W.M. Stanley (1935)
He demonstrated that viruses consist largely of proteins.
What type of genetic material do viruses contain?
RNA or DNA
No virus contains both RNA and DNA.
What are bacteriophages?
Viruses that infect bacteria
Bacteriophages are usually double stranded DNA viruses.
What is the function of the capsid in a virus?
Protects the nucleic acid
The capsid is made of subunits called capsomeres.
Name some diseases caused by viruses.
Mumps, smallpox, herpes, influenza, AIDS
These diseases affect both humans and plants.
What symptoms are caused by plant viruses?
Mosaic formation, leaf rolling, yellowing, dwarfing
These symptoms indicate viral infection in plants.
What are viroids?
Infectious agents smaller than viruses
They lack a protein coat and consist of free RNA.
Who discovered viroids and in what year?
T.O. Diener in 1971
He found viroids caused potato spindle tuber disease.
What are prions?
Abnormally folded proteins causing infectious neurological diseases
They are similar in size to viruses.
What is a notable disease caused by prions?
Bovine spongiform encephalopathy (mad cow disease)
Another example is Creutzfeldt-Jakob disease (CJD) in humans.
What are lichens?
Symbiotic associations between algae and fungi
The algal component is called phycobiont and the fungal component mycobiont.
What role does algae play in lichens?
Prepares food for fungi
Algae are autotrophic, providing sustenance for the heterotrophic fungi.
What is the role of fungi in lichens?
Provides shelter and absorbs nutrients
Fungi help retain moisture and minerals for the algal partner.
True or False: Lichens grow well in polluted areas.
False
Lichens are good pollution indicators and do not thrive in polluted environments.
