Why Is Agar Needed In A Plaque Assay Quizlet?

What does the plaque assay determine?

The plaque assay can be used to purify a clonal population of virus or to determine viral titer as plaque-forming units per ml (pfu/ml) so that known amounts of virus can be used to infect cells during subsequent work..

How many viruses are needed to form a plaque?

One virusOne virus is enough to form a plaque. So for one-hit kinetics, the number of plaques is directly proportional to the first power of the concentration of the virus inoculated. So that’s why you get a straight line. Most viruses follow one-hit kinetics, i.e., one virus is enough to form a plaque.

What is the purpose of having a hard agar base in the plaque forming unit assay?

Active and infectious bacteriophage particles. It’s important to use hard agar with soft agar overlay because The hard agar underneath the soft agar overlay is where you make a lawn streak of your bacteria. Since phage can only grow in the presence of bacteria, this is the only way you can visualize plaques.

Which of the following descriptions fits a chronic viral infection?

Which of the following descriptions fits a chronic viral infection? … Long periods of time with essentially zero viral replication, punctuated by outbreaks of active replication and disease manifestation. Infected individuals are largely non-infectious between outbreak periods.

What is the plaque method?

Plaque Method. method in which a sample of bacteriophage is mixed with host bacteria and melter agar, poured into a, petri dish, and following several viral multiplication cycles, all of the bacteria in the area surrounding the virus are destroyed. Plaques.

What is a plaque purified virus?

Virus stocks prepared from a single plaque are called plaque purified virus stocks. To prepare such virus stocks, the tip of a small pipette is inserted into the agar overlay above the plaque. … The viruses within the agar plug move into the buffer, which can then be used to infect cultured cells.

How do you count phages?

The number of phage particles contained in the original stock phage culture is determined by counting the number of plaques formed on the seeded agar plate and multiplying this by the dilution factor. For a valid phage count, the number of plaques per plate should not exceed 300 nor be less than 30.

How do all Viruses differ from bacteria?

All viruses have is a protein coat and a core of genetic material, either RNA or DNA. Unlike bacteria, viruses can’t survive without a host. They can only reproduce by attaching themselves to cells. In most cases, they reprogram the cells to make new viruses until the cells burst and die.

What is hard agar?

The hard agar is the substrate for bacterial growth. The soft agar is used to mix the bacteria and phage dilutions which is then spread over the hard agar.

What is a bacteriophage plaque?

1 Introduction. A phage plaque is a clearing in a bacterial lawn. Plaques form via an outward diffusion of phage virions that is fed by bacterial infection. Anything that slows phage diffusion can impede plaque development and thereby plaque size.

What does the plaque assay determine quizlet?

plaque assay. -measuring viral titer. -one way to measure viral titer is to detect the killing of susceptible host cells. The basis of the plaque assay is to measure the ability of a single infectious viral particle to form a “plaque” on a confluent “lawn” of susceptible cells.

What does a plaque represent?

Plaque, in microbiology, a clear area on an otherwise opaque field of bacteria that indicates the inhibition or dissolution of the bacterial cells by some agent, either a virus or an antibiotic. It is a sensitive laboratory indicator of the presence of some anti-bacterial factor.

What is the assumption for how a phage plaque is formed?

Plaque-forming units (PFU) Refers to the assumption that one phage infects one bacterial cell so the plaques can be counted to give an accurate statistical estimate of the amount of phage in a sample.

Why do you need to dilute the phage culture before the plaque assay?

Since viruses can grow to incredibly high concentrations, we need to dilute them in order to count them effectively. Perform dilution of the bacteriophage culture .