Chapter 13- Part 2 (Microbiology)

What are the three steps of growing bacteriophages using the plaque method?

1.) A bacteriophage sample is mixed with the host bacteria and melted agar. 2.) The agar containing the bacteriophages and host bacteria is then poured into a Petri plate containing a hardened layer of agar growth medium. 3.) Each virus infects a bacterium, then multiples, and releases hundreds of new viruses (when they're multiplying, you know that they're infecting).

What are the three steps of cell cultures?

1.) A tissue is treated with enzymes to separate the cells. 2.) Cells are suspended in culture medium. 3.) Normal cells or primary cells grow in a monolayer across the glass or plastic container. Transformed cells or continuous cell cultures do not grow in a monolayer.

What are the five stages of the lytic cycle?

1.) Attachment- the phage attaches to the surface of the host. 2.) Penetration- the viral DNA enters the host cell. 3.) Biosynthesis- phage DNA replicates and phage proteins are made. 4.) Maturation- new phage particles are assembled. 5.) Lysis- the cell lyses, releasing the newly made phages, and the bacteria cell dies.

What are the steps of Multiplication of DNA- Containing of Animal Viruses?

1.) Attachment: Virion attaches to host cell 2.) Entry and Uncoating: Virion enters cell, and its DNA is uncoated. 3.) A portion of viral DNA is transcribed, producing mRNA that encodes "early" viral proteins. 4.) Biosynthesis: Viral DNA is replicated, and some viral proteins are made. 5.) Late translation; capsid proteins are synthesized. 6.) Maturation: Virions mature. 7.) Release: Virions are released

What are the three methods used for culturing animal viruses in the lab?

1.) Living Animals 2.) Embryonated Eggs 3.) Cell Cultures

What are the three important results from lysogeny?

1.) Lysogenic cells are immune to reinfection by the same phage. 2.) Host cells may exhibit new properties. Example: The prophage can carry a gene coding for toxins produced by a bacterium. 3.) Special Transduction is possible by lysogeny (because they are able to be transferred from one cell to the next).

What are the five steps to the lysogenic cycle?

1.) Phage attaches to host cell and injects DNA 2.) Phage DNA circularizes and enters lytic cycle or lysogenic cycle 3.) Phage DNA integrates within the bacterial chromosome by recombination, becoming a prophage. 4.) Lysogenic bacterium reproduces normally 5.) Occasionally, the prophage may excise from the bacterial chromosome by another recombination event, initiating a lytic cycle.

Simian AIDS

1986; Green Monkeys

Feline AIDS

1987; Cats

What is the process of cultivating in embryonated eggs?

A hole is drilled in the shell and the viral tissue is injected; viral growth is signaled by the death of the embryo.

When using the plaque method to grow bacteriophages in the lab, what temperature do you incubate the upside plate at?

All enterobacteria is incubated at 37 degrees C for 18 hours.

Helical Viruses

Are hollow cylinders surrounding the nucleic acid.

Polyhedral Viruses

Are many sided.

How can bacteriophages be grown in the lab?

Bacteriophages can be grown either in suspension of bacteria in liquid media, or in bacterial cultures on solid media.

Cell Cultures

Cells grown in culture media in the lab.

What is an example of lysogeny?

Chicken Pox- gene can lay dormant in cells, and turn into a different form and become active later on in life causing shingles.

Plaques

Clearings in a bacterial lawn resulting from lysis (to break or destroy) of phages.

What are the pros of embryonated eggs and cell culture?

Convenient and inexpensive form of host for many animal viruses.

Lytic Cycle

During the Lytic Cycle, a phage causes the lysis and death of a host cell.

What type of virus is the influenza virus?

Enveloped helical

Enveloped Viruses

Enveloped helical or enveloped polyhedral viruses.

What type of virus is the herpes virus?

Enveloped polyhedral

Plaque Method

For detecting and counting viruses on solid media.

Complex Viruses

Have complex structures

What happened in living animals in 1990 that was so important?

Immunodeficient mice were grafted to produce human T cells and human globulin.

Where does translation take place?

In the cytoplasm.

What is cultivating embryonated eggs used for?

It can be used to grow viruses for some vaccines.

_____________________ causes diseases similar to ______ provide animal models for studying viral growth in different tissues.

Lentivirus; HIV

What are the two alternative mechanisms that bacteriophages can multiply by?

Lytic Cycle and Lysogenic Cycle

What's the major difference between the lytic cycle and the lysogenic cycle?

Lytic Cycle: Viruses are being released, and will continue to invade other cells . Lysogenic Cycle: Cells are inactive, and will become active depending on the event that occurs .

What is an example of a complex virus?

Many bacteriophages have a polyhedral capsid with a tail attached.

What are some of the living animals used when culturing animal viruses?

Mice (have close homology and genetic characteristics that are similar to humans), rabbits, and guinea pigs.

Multiplication of DNA-Containing of Animal Viruses

The DNA of most DNA viruses is released into the nucleus of the host cell; transcription of viral DNA and translation produce viral DNA and, later, capsid proteins; capsid proteins are synthesized in the cytoplasm of the host cell.

Plaque Forming-Units

The concentration of viral suspension by the number of plaques.

True or False: Cell culture is the preferred type of growth media for many viruses.

True, this is because cell cultures are more convenient to work with than whole animals or embryonated eggs.

True or False: After several multiplication cycles, the bacteria is then destroyed, which produces plaques.

True.

True or False: Animal viruses are cultured only in living animals.

True.

True or False: Human viruses grown in animals, do not cause disease.

True.

True or False: Some cell cultures can be cultivated in embryonated eggs.

True.

Western Blotting

Used to detect a virus and identify its reaction with antibodies (if you want to look at the protein).

Why are animal viruses cultured?

Used to study the immune system's response to viral infections (animals can be inoculated with the virus and observed for signs of disease).

Cytopathic Effects

Useful for identifying viruses. W

Lysogeny

When viruses have their DNA incorporated as prophage into the DNA of the host cell; the phage remains inactive.