Microbiology Lecture Exam
Card Set Information
Microbiology Lecture Exam
Obligate intracellular parasites
(have to)(inside)(cell) (kill/harm host cell)
They have to get inside a cell to reproduce and then they kill or harm a host cell-usually.
What is the Basic Cell Sturcture?
Capsid (protein shell)
Double-strand DNA, single strand DNA, D.S RNA, and S.S RNA.
: also have an envelope; envelope is a piece from previous hoat cell.
(phospholipid bilayer with embedded proteins)
What identifies a viruse?
-enveloped or not
-type of genetic material
Types of Viruses? Determined by host cells
1. Bacterial viruses (bacteriophage)
-infects bacterial cells--bacteria eater
2. Plant virsues
3. Animal viruses
-infects animals; including human pathogens
Generalized Life Cycle? (5 steps)
1. Attachment (important step) to host cell
viruses only attach to a host cell that only have appropriate receptors on cell surface.
(This determines the virus specificity for a host cell) "What host can viruses infect?
Virus get into host cell, and capsid is removed (genetic code is avaliable)
Host phagocytosis virus
-Virus injects nucleic acid
-Viral envelope fuse with hos membrane
3. Replication (synthesis of viral parts)
Using viral genetic code
Use host cells materials (a.a, tRNA, etc) and ribosomes
-New viral genetic material
-New viral proteins (for capsid or envelope-if appropriate)
Pieces of virus are put together to make new viruses. [virons]
Place genetic material in capsid
5. Released from host
Host cell lysis (dies)
Virus can bud out of cell
Specific viral life cycle?
1. Lytic cycle- see p. 7.6
Cause lysis of host cell
2. Lysogenic cycle- see p. 7.7
Sometimes host cell lysis; viral DNA become part of host DNA (genome)
(1 and 2 happens in bacteria cells0
3. Retrovirus life cycle. see 7.8
Happens in animals
How virus help identify a bacteria?
(Using viruses that do lytic cycle)
A unkown bacteria is inoculated with a phage that kills E. coli, a phage that kills Salmonella, and a phage that kills Proteus.\
Bacteria only dies with the phage that kills Salmonella, hence, the bacteria had the correct receptors for the phage to infect.
What is retoviruses?
Perform the reverse of normal transcription.
RNA make DNA by enzyme=reverse transcriptase
: H.I.V=Human ImmunoDeficiency Virus (Kills key immune system cells, patient becomes immundeficent)
How to treat viral diseases?
Some viral diseases can be trated with anti-viral medications.
Many viruses-no safe treatment.
Viral replication involves host material and host systems--if blocking viral replication, you can block these host processes.
Vaccines- teaching the immune system to attack viruses.
Cannot be destroyed ny standard sterization
Cause [transmissible spongiform
can be transmitted holes in brain
Ex. mad cowl disease
Prions protein- some a.a sequence as normal brain protiens fold differently.
Reproduce-when a prion proteim bumbs into a normal protein, it causes that protein to fold like a prion protein.
Transmission- ingestion of infected CNS (brain) tissue.