2.2 - Viruses Flashcards
Characteristics of living things
Movement, respiration, sensitivity, growth, reproduction, excretion, & nutrition
Why are viruses non-living things?
Because they do not possess specific characteristics necessary to be considered living.
They can only REPRODUCE with a host organism [and evolve]
Viruses
Small, infectious particles containing genetic material surrounded by a capsid
Capsid
Protein coat that surrounds the DNA or the RNA of a virus
RNA
Nucleic acid that carries genetic information that provides instructions for synthesizing protein
Epidemic
Large-scale outbreak of disease, usually confined to a limited geographic region
Pandemic
Epidemic that occurs over a widespread geographic area, often globally
Bacteriophage
Virus that infects bacteria by injecting their DNA into the bacterium
Virus Structure
Viruses all consist of an RNA or DNA molecule surrounded by a capsid. Some also are surrounded by an envelope.
Lysis
Rupturing of a host cell, releasing about 100 to 200 new viruses into its surroundings
Lysogeny
State of dormancy where viral DNA stays in the host’s cell for many cycle generations
Methods of transmissions and the viral diseases they cause
Bite by infected mammal - Rabies
Exchange of body fluids - HIV/AIDS
Airborne & by contact - Influenza, common cold, chicken pox
Direct contact - Measles, mumps
Gene therapy
Method of treating disease where genes are introduced into cells to replace, supplement, or repair a defective gene. Viruses are used to deliver drugs or genes to targeted cells by replacing the viral DNA in capsids with drugs.
How do vaccines help to protect against viral diseases?
Vaccines imitate weakened infections to engage body’s natural defenses
Viroids
Small, infectious pieces of RNA
Prion
Infectious proteins
