Acellular microbes Flashcards
the smallest virus is about the size of
large hemoglobin molecule of RBC
genome of a typical virion consists of
either DNA or RNA surrounded by capsid
nucleocapsid =
nucleic acid + capsid (protein coat)
features that distinguish viruses from living organisms
- lack of enzymes necessary in energy production
- unable to replicate on their own
- depend on the resources of host cells
which type of viruses is more resistance to adverse conditions, why?
nonenveloped (naked) viruses, since attachment proteins are on the capsid (stronger than envelope)
single-stranded positive sense RNA functions as
mRNA in viruses
Bacteriophages
bacterial viruses (viruses that infect bacteria)
vibrio cholera
virulent bacteriophages
always causes a lytic cycle which ends with the destruction of the bacterial cell
temperate phages (lysogenic)
Their DNA remains integrated into the bacterial cell chromosome
do not immediately initiate the lytic cycle like Virulent bacteriophages
latent virus
viruses that do not initiate biosynthesis right away
cold sores (latent virus infections)
cold sores (fever blisters)
Caused by Herpes simplex virus I (HSV I)
the cold sores come and go
what are the triggers for latent virus infections
fever, sunlight, or excessive stress
genital herpes
caused by Herpes simplex virus II (HSV II)
shingles
painful nerve disease
Caused by Varicella zoster virus (VZV)
Causes chickenpox (Varicella) as primary infection
when the body’s immune defenses become weakened by old age or disease, the latent chickenpox virus resurfaces to cause shingles (zoster)
Epstein-Barr virus (EBV)
a type of herpes virus
causes infectious mononucleosis (not a type of cancer)
causes three types of human cancers:
a-nasopharyngeal carcinoma
b-Burkitt lymphoma
c- B-cell lymphoma