33 Questions
What is a characteristic that viruses do NOT have?
The ability to maintain homeostasis
What is a similarity between viruses and living things?
The possession of some properties of life
What can be done to viruses?
Kill them
What is a difference between viruses and living things?
Viruses lack the ability to maintain homeostasis, but living things do not
What is an example of what can be done to viruses?
Crystallizing them
What is the debate about viruses?
Whether they are living or non-living
What is the classification of viruses in terms of life?
They are considered non-living entities
What is a key characteristic of viruses that distinguishes them from living cells?
Their inability to replicate on their own
What is the relationship between viruses and their host cells?
Viruses are dependent on their host cells for reproduction
What is the main difference between viruses and other microorganisms?
Their ability to reproduce independently
What happens to the host cell during the viral replication process?
It undergoes lysis
What is the function of tail fibers in viruses?
To attach to the host cell
What is the result of the release of new virions from the host cell?
The host cell is destroyed and new virions are released
What does the phage penetrate to inject its DNA?
Cell wall
What is the result of the phage penetrating the host cell?
The phage's DNA is injected
What is the role of the host cell in the viral replication process?
To provide a site for viral replication
What is the outcome of the viral replication process?
The destruction of the host cell and release of new virions
What is released into the bloodstream from the liver?
Merozoites
What is the function of the tail core?
To penetrate the host cell
What is the result of maturation?
Viral components are assembled
What is the purpose of the sheath?
To contract and inject DNA
What is the final stage of the viral lifecycle?
Release
What is the structure that contains the viral DNA?
Capsid
What is the function of the contractile tail in bacteriophages?
To attach to the host cell
What is the role of reverse transcriptase in retroviruses?
To transcribe viral RNA into DNA
What is the characteristic of viroids?
They are single-stranded RNA molecules
What is the result of a retrovirus infecting a cell?
The cell produces viral proteins and RNA
What is the purpose of the lytic cycle?
To release new viruses into the environment
What is the function of the capsid in a virus?
To protect the viral genome
What is the characteristic of prions?
They are infectious proteins
What is the role of the host cell in the lytic cycle?
To provide a location for viral replication
What is the outcome of a virus infecting a cell?
The cell lyses and releases new viruses
What is the function of the bacteriophage tail fibers?
To attach to the host cell
Study Notes
Viruses, Viroids, and Prions
- Viruses are both living and non-living, having some properties of life but not others
- They can be killed and even crystallized like table salt
- However, they can't maintain a constant internal state (homeostasis)
Characteristics of Viruses
- Contain RNA or DNA genome
- Have a protein coat (capsid) that protects the genome
- Can inject their genome into a host cell
- Can be killed with disinfectants or heat
- Can be crystallized like table salt
- Can't maintain a constant internal state (homeostasis)
Retroviruses
- Contain RNA, not DNA
- Contain the enzyme reverse transcriptase
- Can inject their RNA and reverse transcriptase into a host cell
- Can convert their RNA into DNA using reverse transcriptase
- Examples include HIV (human immunodeficiency virus) and feline leukemia virus
Viroids and Prions
- Viroids are small, circular RNA molecules that infect plants
- Prions are infectious proteins that can cause diseases such as mad cow disease and kuru
- Prions are normal body proteins that get converted into an alternate configuration by contact with other prion proteins
- They have no DNA or RNA, and the main protein involved is called PrP
Viral Replication
- Viruses are very specific as to which species they attack
- Humans rarely share viral diseases with other animals
- Eukaryotic viruses usually have protective envelopes made of membrane from the host cell
- The lytic cycle of viral replication involves attachment, penetration, replication, assembly, and release of new viruses
Bacteriophage Replication
- Bacteriophage inject their nucleic acid into the bacterial cell
- They lyse (break open) the bacterial cell when replication is finished
- The process involves attachment, penetration, replication, assembly, and release of new phages
Explore the fascinating world of viruses, viroids, and prions. Are they living or non-living? Take this quiz to find out more about these microscopic entities.
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