Viruses and Their Reproduction

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Questions and Answers

What is the primary component that viruses are enclosed in?

  • Cytoplasm
  • Cell wall
  • Capsid (correct)
  • Nucleus

Viruses can reproduce on their own.

False (B)

What type of genetic material do most viruses contain?

RNA or DNA

Viruses that specifically infect bacterial cells are known as ______.

<p>Bacteriophages</p> Signup and view all the answers

Which of the following viruses is associated with the Lytic Cycle?

<p>Rabies (A)</p> Signup and view all the answers

All viruses can infect any type of cell.

<p>False (B)</p> Signup and view all the answers

What enzyme do retroviruses use to reverse transcribe RNA into DNA?

<p>Reverse transcriptase</p> Signup and view all the answers

Match the following viruses with their corresponding cycles:

<p>Rabies = Lytic Cycle HIV = Lysogenic Cycle Chicken Pox = Lysogenic Cycle Influenza = Lytic Cycle</p> Signup and view all the answers

Which of the following is a method by which vaccines establish immunity?

<p>By using weakened or inactivated viruses (D)</p> Signup and view all the answers

Prions are infectious agents made up of nucleic acids.

<p>False (B)</p> Signup and view all the answers

Who discovered the first smallpox vaccine?

<p>Edward Jenner</p> Signup and view all the answers

A _______ is a genetically altered virus that transports a good gene into a cell.

<p>vector</p> Signup and view all the answers

Match the following viruses with their corresponding categories or diseases:

<p>HIV = AIDS Ebola = Hemorrhagic fever Polio = Paralysis Measles = Rash and respiratory symptoms</p> Signup and view all the answers

Which of the following is NOT an example of a virus?

<p>Mad Cow Disease (B)</p> Signup and view all the answers

Viroids are known to affect both animals and plants.

<p>False (B)</p> Signup and view all the answers

What type of RNA do viroids possess?

<p>circular strand of RNA</p> Signup and view all the answers

Flashcards

Viruses

Small infectious agents that replicate inside living cells.

Vaccine

A biological preparation that provides active acquired immunity.

Viroids

Infectious agents composed of a single, circular strand of RNA.

Prions

Infectious protein particles that affect the brain or neural tissue.

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Gene Therapy

Using genetically altered viruses to deliver a good gene to a cell

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Vector (in Gene Therapy)

A genetically altered virus that delivers a good gene into a cell.

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Edward Jenner

Scientist who is credited with the discovery of the smallpox vaccine.

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Immunity

The ability of an organism to resist a particular infection or toxin.

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Virus Replication

Viruses hijack host cell machinery to create more viruses.

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Lytic Cycle

A viral replication process where a virus rapidly infects, replicates, and causes the host cell to burst.

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Lysogenic Cycle

Viral replication where a virus integrates its DNA into the host cell's DNA and replicates along with it for a period of time.

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Retrovirus

A type of RNA virus that makes a DNA copy of its RNA genome during infection using reverse transcriptase.

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Host Cell

A cell that is infected and used by a virus for replication.

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Protein Receptors

Proteins on the surface of cells that viruses use to recognize and bind to.

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Bacteriophage

A virus that infects bacteria

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Study Notes

Viruses

  • Infectious particles, composed of either RNA (most common) or DNA, enclosed in a protein coat (capsid).
  • Some viruses have a lipid envelope.
  • Viruses are not considered living organisms.
  • They do not metabolize, reproduce, consume food, move on their own, grow, or have cells.
  • They invade cells, take control of cellular machinery, and use it to reproduce, creating millions of new viruses.

Viral Reproduction

  • Lytic Cycle:
    • Viruses infect, affect, and replicate rapidly within the host cell.
    • The virus enters the cell, replicates many copies, and causes the host cell to burst.
    • Examples: Rabies, Measles, influenza, Hepatitis
  • Lysogenic Cycle:
    • Viruses infect and remain dormant before affecting the host.
    • The viral DNA integrates with the host cell's DNA, and replicates along with the host's DNA.
    • Examples: Mumps, HIV, Herpes, Chicken Pox

Retroviruses

  • Special type of RNA-based virus.
  • Retroviruses make a DNA copy of their RNA after infecting a cell and insert it into the host cell's DNA.
  • This process utilizes reverse transcriptase.
  • Example: HIV, COVID-19

How Viruses Find Host Cells

  • Host cells contain protein receptors on their plasma membrane.
  • Viral capsids have ligands that bind to host cell receptors, enabling viral entry.
  • Viruses are highly specific to the type of cells they infect (plant, animal, bacterial).

Examples of Viruses

  • Smallpox
  • Chickenpox
  • Herpes
  • Hantavirus
  • Mumps
  • Measles
  • Polio
  • Hepatitis A, B, C
  • West Nile
  • Coronavirus (COVID-19)
  • Encephalitis
  • Influenza
  • Meningitis
  • Ebola
  • HIV
  • Rubella
  • Mononucleosis
  • Rabies
  • HPV
  • Yellow Fever
  • H1N1 (Swine Flu)

Bacteriophages

  • Viruses that infect bacteria.
  • Beneficial to human survival.

Viroids

  • Infectious RNA agents
  • Composed of a single, circular strand of RNA.
  • Lacking a protein coat.
  • Primarily infect plants, but some human infections are known.
  • Example: Hepatitis D

Prions

  • Infectious proteins
  • Affect the brain or neural tissue.
  • Untreatable and fatal.
  • Examples: Mad Cow Disease, Creutzfeldt-Jakob Disease

Vaccines

  • Used to establish immunity against viruses.
  • Discovered by Edward Jenner (smallpox vaccine, 1796)
  • Created from weakened viruses or viruses with removed nucleic acid (RNA or DNA).
  • The body recognizes and destroys the viruses, building an immune response, capable of recognizing the virus upon re-exposure.
  • Example: H1N1 (swine flu) vaccine

Viruses as Vectors

  • Viruses are used in gene therapy.
  • Genetically altered to carry and deliver a good gene into a cell needing it.
  • Process allows for targeted gene delivery and modification in cells, potentially treating genetic diseases.

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