Microbiology 2 Flashcards
The general steps in viral replication (in order) are?
adsorption, penetration, synthesis, assembly, release.
A major difference in the replication of animal viruses and bacteriophages is the ______ step
Penetration
Viral cycles that end in release of the new phages and immediate destruction of the host bacterial cell are referred to as _______.
Lytic
How does bacteriophage DNA get into the host cell?
It’s injected
the statement that best describes the role of viral surface proteins or spikes.
Viral spikes provide means of attachment to host cell surface.
What term describes the type of bacteriophage infection in which the host bacteria are lysed and killed as a result of the infection?
Lytic
What term describes the type of bacteriophage infection cycle where the bacteriophage DNA is inserted into the host cell DNA as a prophage and the infected bacteria can continue to grow and divide?
Lysogenic
Please order the following steps to reflect the order in which they occur in the replication cycle of an animal virus.
Adsorb, penetration, synthesis, assembly, release.
Which of the following descriptions fits a chronic viral infection?
Characterized by continuous production of low levels of viral particles, even in the absence of disease symptoms. The organism is usually still highly infectious during this time.
Which of the following describes a latent 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.
Steps of lytic cycle or typical bacteriophage?
- Attachment:
Phage attaches to specific receptors.
2: Genome Entry:
Tail contracts, DNA is injected into the bacterial cell.
- Synthesis:
Phage genome is transcribed, proteins are translated. Phage DNA is replicated. - Assembly:
Phage components are assembled into mature virion particles.
5: Release:
Bacterial cell lyses, many new infectious virions are released.
Please place the steps for animal virus replication in the correct sequence.
1: Virus attaches to receptors on the host cell cytoplasmic membrane.
2: Virus enters the host cell by fusion or endocytosis.
3: Viral genome is uncoated.
4: Structural and catalytic viral genes are expressed.
5: Multiple copies of the viral genome are synthesized.
6: New viral particles assemble and mature.
7: Viruses are released from the host cell by budding or during apoptosis of the host cell.
Some phages are medically important for all of the following reasons EXCEPT
they also infect eukaryotic cells.
A virus usually infects only certain types of cells due to
interactions between viral and cellular surface molecules.
Which of the following is required for prion replication?
Abnormal prion protein
Nematode characteristics?
Roundworms, cylindric body, an example is pinworms, digestive tract including mouth and anus.
Cestode characteristics?
Lack digestive system; absorb nutrients from host. Flat-ribbon shaped bodies. An example is a tapeworm. Intermediate hosts include cattle and pigs.
Trematode characteristics?
Flukes. One opening for nutrient intake and exit of wastes. Flat-leafed shaped bodies. An example is schistosomes.
Which of the following statements about fungal structure are TRUE?
Can be both unicellular and multicellular.
Group of cells together or a series is called a hyphae or (Hyphal mass).
Which of the following statements about the economic impact of fungi is FALSE?
Fungi commonly cause serious human diseases that lead to loss of work hours.
Which of the following statements about the medical importance of algae are TRUE?
Some algae produce powerful neurotoxins that accumulate in shellfish.
Examples of algal toxins that impact humans are saxitoxins and gonyautoxin.
Which of the following about fungi is FALSE?
All fungi are unicellular.
Limited host range?
The range of host cells that a virus can infect.
Helminths are most commonly transmitted to humans by
the gastrointestinal route.
Not alive viruses
inactive outside host cell, no cellular structure, no physiology. Cannot infect host.
Obligate intracellular parasites?
Require a host cell (and host machinery) to reproduce.
Alive viruses
No physiology but viruses alter the physiology of the host. Able to infect host.
Species virus
Specific bacteriophages
Structure of virus
Protein shell (capsid), genome (DNA or RNA), no ribosomes, mitochondria and no metabolism
Narrow virus
Identity of spikes on the virus.
Spikes will then find matching receptors on host cell surface.
Classification of viruses?
Classification strategy
Virus sizes?
Viruses are very small, the size of nanometers (nm). Nanometers are 1/100th of a micron.