Viruses and Their Reproduction

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Questions and Answers

What is necessary for viruses to reproduce?

In a laboratory setting

Within a virus particle

In presence of light

Inside a living cell (correct)

Which of the following characteristics is NOT true about viruses?

They can mutate.

They have metabolism. (correct)

They contain DNA or RNA.

They are non-cellular.

What is true about the reproduction of viruses compared to cells?

Cells reproduce only within a host cell.

Cells can reproduce independently without a host. (correct)

Viruses reproduce either sexually or asexually.

Viruses can reproduce independently without a host.

What process do viruses use to make host cells produce viral components?

Host cell manipulation Signup and view all the answers

What happens to the host cell at the end of the viral reproductive cycle?

It gets destroyed. Signup and view all the answers

Which statement accurately describes the role of vaccines in relation to viral infections?

Vaccines stimulate the immune system to recognize pathogens more effectively. Signup and view all the answers

What is the primary reason that antibiotics are ineffective against viral infections?

Antibiotics specifically target bacteria, not viruses. Signup and view all the answers

Which statement about viral genetic material is true?

It can consist of either DNA or RNA. Signup and view all the answers

Which of the following diseases is NOT typically caused by a virus?

Tuberculosis Signup and view all the answers

What is a characteristic that distinguishes viruses from living organisms?

They can be crystallized. Signup and view all the answers

What makes viral diseases particularly challenging to treat?

Viral diseases are often asymptomatic until late stages. Signup and view all the answers

What term describes the viral components produced by the host cell?

Viral parts Signup and view all the answers

Which of the following best describes the entry of a viral infection into a host cell?

The viral genetic material injects itself into the host cell. Signup and view all the answers

What does the word 'virus' derive from in Latin?

poison Signup and view all the answers

Which of the following describes the state of a virus when it is outside of a living cell?

Inactive and ceases all activities Signup and view all the answers

What must a virus's capsid shape do to successfully infect a host cell?

Align with the host cell's receptors Signup and view all the answers

Which statement is true about the virus's structure?

The protein coat of a virus is called the capsid. Signup and view all the answers

How do viruses demonstrate specificity towards the cells they infect?

Through precise binding to host cell proteins Signup and view all the answers

What is implied by the statement that viruses are non-cellular?

Viruses do not have cellular structure or compartmentalization. Signup and view all the answers

What type of virus can the Papaya Ringspot Virus infect?

Plant cells Signup and view all the answers

What is the role of the base plate in a virus?

To facilitate binding to host cells Signup and view all the answers

What happens during a lytic infection?

The host cell bursts, releasing new viral particles. Signup and view all the answers

Which of the following characteristics distinguishes the lysogenic cycle from the lytic cycle?

The viral DNA is replicated along with host DNA. Signup and view all the answers

What is the role of tail fibers in the lytic cycle?

They help the virus attach to the host cell's surface. Signup and view all the answers

What primary event occurs after the viral DNA is injected into the host cell during the lytic cycle?

The host cell is directed to produce viral genomes and proteins. Signup and view all the answers

What is a defining feature of lysogenic viruses?

They can remain inactive for an extended period. Signup and view all the answers

Which of the following processes occurs during the lytic cycle?

The host cell's DNA is destroyed after virus production. Signup and view all the answers

In the lytic cycle, what typically happens to the host cell after producing viral particles?

It bursts to release the new viruses. Signup and view all the answers

When a lysogenic virus integrates its DNA into the host genome, its DNA is considered to be:

Inactive until certain conditions trigger replication. Signup and view all the answers

What characterizes the lysogenic cycle in relation to the prophage?

The prophage integrates into the bacterial chromosome. Signup and view all the answers

When does the transition from the lysogenic cycle to the lytic cycle typically occur?

When specific environmental conditions trigger activation. Signup and view all the answers

Which statement about bacterial cell division in the context of the lysogenic cycle is correct?

The bacterial chromosome is copied and shared with daughter cells. Signup and view all the answers

What is the primary outcome of the lytic cycle?

Production of new viral particles leading to cell lysis. Signup and view all the answers

In what way does the prophage differ from an active viral infection?

The prophage remains inactive within the bacterial genome. Signup and view all the answers

What happens during the bursting of the host cell in the lytic cycle?

New viruses are released into the environment. Signup and view all the answers

Which of the following conditions may trigger the transition from the lysogenic cycle to the lytic cycle?

Chemical exposure or radiation. Signup and view all the answers

Which feature is NOT a determinant in the propagation of the lysogenic and lytic cycles?

Size of the viral genome. Signup and view all the answers

Study Notes

Virus Basics

Viruses are infectious particles, but they are nonliving.
The word "virus" comes from the Latin word meaning "poison."
Viruses are parasites, requiring a host to survive.
A host is the living organism a parasite lives on or in.
Viruses are extremely small, needing an electron microscope to be seen.

Viral Characteristics

Viruses are active only inside living cells.
Outside a host cell, viral activity ceases, but the virus retains its ability to infect.
Viruses can be crystallized & stored for long periods but remain infective.
Viruses vary widely in size and structure.
All viruses enter a living cell and use the cell's mechanism to create more viruses.
Viral structure includes a capsid (a protein coat), base plate, tail fibers, sheath, and DNA or RNA.

Viral Classification

Viruses are non-cellular.
Viruses have two main components: DNA or RNA surrounded by a protein coat, called the capsid.
The capsid has a specific shape matching receptors on a host cell so the virus can enter.
When a virus attaches to these receptors, the cell is tricked into allowing the virus inside.
Viruses are highly specific to the cells they infect. Plant viruses only infect plant cells, animal viruses only infect animal cells, and similar viral types for certain eukaryotes/bacteria.

Viral Reproduction

Viruses reproduce only inside living cells.
Viruses hijack the host cell instructing it to produce viral components rather than cellular components (e.g. proteins of viral capsids etc).
The viral genome takes over the host cell, directing the cell to create new viruses.
The host cell produces copies of the viral DNA and creates capsid proteins.
The host cell assembles these components into complete new viruses.
The reproductive cycle concludes with the release of numerous new viruses from the host cell, causing the host cell to usually die.
Viral reproduction can be either lytic (immediate destruction of host cell causing cell death) or lysogenic (viral DNA integrates itself into host cell DNA & replicates along with host cell DNA – may stay dormant for a time).

Viral Diseases

There are few cures for viral infections.
Antibiotics are effective against bacteria, not viruses.
Some new antiviral drugs have been developed but primarily slow the viral effects rather than curing.
The control of viral diseases relies on vaccines.
Vaccines contain a harmless variation of the pathogen (harmless form of the virus), which triggers an immune response whereby the immune system learns to recognize the pathogen.
Subsequent exposure to the real virus allows the immune system to respond quickly and effectively.
Examples of viral diseases include flu, colds, chickenpox, AIDS, hepatitis, and West Nile.

Viruses vs. Cells

Viruses lack cellular structure, whereas cells have a membrane, cytoplasm, nucleus, and organelles.
Viruses reproduce only within a host cell whereas cells can reproduce on their own (or in conjunction with other cells for certain processes).
Viruses use DNA or RNA for their genetic material, while cells use DNA.
Viruses do not use energy or obtain nutrients. Cells perform these functions.
Cells respond to their environments and can grow & develop, while viruses cannot.
Viruses evolve, as cells do.

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Description

Test your knowledge on the characteristics of viruses and their reproductive processes with this quiz. Explore how viruses differ from living organisms, the role of vaccines, and the challenges in treating viral diseases. Assess your understanding of viral infections and their impact on host cells.