Ch 33 Flashcards
Define epidemic
Is a disease that rapidly Infects a large number of individuals over a widening area
Define pandemic
Is a worldwide epidemic
Define virulent
The ability of a pathogen to Cause severe disease in a susceptible host
How does HIV cause AIDS?
HIV Parasitize specific types of cells most notably the helper T cells of the immune system which is the bodies defense system against disease. as the T cells drop sign of AIDS this kills people indirectly by making them susceptible to diseases that normally do not arise in those with a functioning immune system
Why is HIV bad for the help tcells/immune system?
HIV causes T helper cells to drop, weakening the immune system making the immune system more susceptible to diseases
What happens when the helper cells are infected
T cell count drops
Define positive sense viruses
Contains the same sequences as the mRNA required to produce viral protein
Define negative sense viruses
The base sequences in the genome are complementary to those in Viral mRNAs
Define ambisense viruses
Control one positive since region and one negative sense region
What are the six phases common to refplicative growth in virtually all viruses
- Attachment to a host cell and entry into the cytosol
- Viral genome transcription and Viral protein production
- Viral genome replication
- Assembly of a new generation of virions
- Exit from the infected cell
- Transmission to a new host
How do you viruses copying there genomes
Some are retroviruses, these retroviruses transcribe RNA to DNA by a viral enzyme called the reverse transcriptase
Some are cDNA which are copies of the genome that is then inserted by viral proteins into the host cell chromosome
What is reverse transcriptase
An enzyme that can synthesize DNA from an RNA template
Define complementary DNA (cDNA)
DNA produced by retroviruses using an RNA transcript as a template and reverse transcriptase
