Plant biology ( VIRUSES)
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Questions and Answers

Virus means what in latin

  • Poison (correct)
  • Kelp
  • Bacti
  • Viron

    • Who discovered Virus and in what year?

  • Dimitri Ivanosky 1892 (correct)
  • Beijerinck 1897
  • Dmitri Ivanosky 1894
  • Dtanley Rendell 1935

    • Who coined tge term virus

  • Bawden 1943
  • Loria 1896
  • Darnell 1987
  • Beijerinck 1897 (correct)

    • What are viruses composed of?

    <p>All of the above</p> Signup and view all the answers

    Who discovered whwt viruses are composed of?

    <p>Stanley Rendell 1935</p> Signup and view all the answers

    Who described viruses as " an obligatory parasitic organism whose size is less than 200micrometer"

    <p>Bawden (1943)</p> Signup and view all the answers

    Who defined virus as a sub microscopic entity capable of being introduced into living cells amd reoroducing such cells.

    <p>Loria(1953)</p> Signup and view all the answers

    "A virus is an entity wgose genome is a nucleic acid either DNA/RNA which reproduces inside living cells and uses their synthetic machinery to direct is synthesis" this definition was givem by?

    <p>Luria and Darnell</p> Signup and view all the answers

    "A small infectious agent that can replicate only inside the living cells of an organism" was defined by?

    <p>Koni et al (2006)</p> Signup and view all the answers

    Virsues are also called?

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

    Stydy of viruses is called Virology in the vranch if microbiology

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

    About how many viruses have been identified

    <p>1,000</p> Signup and view all the answers

    Origin of viruses are know/ clear

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

    Pieces of DNA thatbcan move bacteria cells are know as?

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

    Viruses might have evolved from?

    <p>Plasmids and bacteria</p> Signup and view all the answers

    Viruses are at the - of life

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

    Visruses evolved from?

    <p>Plasmids and Bacteria</p> Signup and view all the answers

    Viruses are considered to be living organisms

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

    Viruses are considered to be living organisms because they contain genetic material,reproduve and evolve through natural selection

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

    A virus is made up of how many main parts?

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

    main parts of A vius are?

    <p>1.Nucleoid/genetic material/ genome 2. Proten coat or Cadpid</p> Signup and view all the answers

    DNA

    <p>Deoxyribonucleic acis</p> Signup and view all the answers

    RNA

    <p>Ribonucleic acid</p> Signup and view all the answers

    Genetic material is located where?

    <p>Within the caspid</p> Signup and view all the answers

    • is a nucleic acid component of a virus located within the caspid

    <p>Genetic materia/ genome/ Nucleiof</p> Signup and view all the answers

    Nucleic acid contains?

    <p>Pentonse,Phosphorosus,Nitrogen bases</p> Signup and view all the answers

    Genome in plant viruses is?

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

    Genome in Animal and bacterial viruses is?

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

    Nucleic acids of DNA viruses is smaller in size than that of nucleic acid of RNA viruses

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

    DNA or RNA molecule may be

    <p>All of the above</p> Signup and view all the answers

    The base in DNA Is called?

    <p>Purine bases</p> Signup and view all the answers

    Tge base in RNA

    <p>Pyrimidine base</p> Signup and view all the answers

    mRNA

    <p>messanger RNA</p> Signup and view all the answers

    The change of a single stranded RNA from positive to negative depends on what?

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

    Types of Nucleic Acids in Virons

    <p>Linear ,circular, Double stranded RNA, Double stranded DNA,Single stranded DNA,Single stranded RNA+, Single stranded RNA-</p> Signup and view all the answers

    The nucleic acids determines the propertoes of the virus and is also the infecteous part of the virus

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

    The protein coat surrounding the nucleic acid component of a virus is called?

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

    Caspids is made up of small units called?

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

    Capsometers which are made up of one or more different protein units are called?

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

    Shapes of caspids?

    <p>Spherical,Helial,polyhedral,binal complex</p> Signup and view all the answers

    Which of the following is false about caspids

    <p>Contains codes for the synthesis of proteins and it own synthesis</p> Signup and view all the answers

    Which is an example of spherical or golf ball like

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

    Polyhedral

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

    Helical

    <p>Tobacco mosaic</p> Signup and view all the answers

    Complex

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

    Caspid is covered with...... thick envelope

    <p>10-18mm</p> Signup and view all the answers

    Amount of nucleic acid in a virys varies from?

    <p>1-50 percent</p> Signup and view all the answers

    Caspid is covered with a thick envelope called

    <p>Viral envelope</p> Signup and view all the answers

    Viral envelope consists of?

    <p>Proteins,lipids,and carbohydrates</p> Signup and view all the answers

    Viruses that have viral envelopes are called?

    <p>Enveloped viruses</p> Signup and view all the answers

    Viral envelope provides shape and ridigity found in viral envelopes

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

    Viruses without viral envelopes are called

    <p>Naked( Nucleopasid) virus</p> Signup and view all the answers

    Some enveloped viruses have spikes which allows the virus to attach tonits host cells.

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

    First Enzyme discorved was?

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

    Neuraminidase, DNA-dependent RNA polymerase (transcriptases), reverse transcriptase. Essential for infection and growth

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

    In some viruses, the capsid is covered with --------thick envelope called viral envelope

    <p>10-18mm</p> Signup and view all the answers

    neuraminidase is in?

    <p>in Influenza virus and Paramyxo viruses)</p> Signup and view all the answers

    DNA-dependent RNA is called

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

    DNA-dependent RNA polymerase were detected in?

    <p>Vaccinia virus and several other animal, plant and insect viruses</p> Signup and view all the answers

    These enzymes are collectively called

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

    synthesize messenger RNA (mRNA) from the nucleic acid of a virus

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

    which enzyme synthesizes DNA from ssRNA template. These enzymes are essential for infection and growth of viruses.

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

    A reverse transcriptase has been detected in RNA

    <p>Tumor virus</p> Signup and view all the answers

    Carbohydrates have been

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

    The most widely used system for the classification of viruses proposed by?

    <p>Lwoff et al. (1962)</p> Signup and view all the answers

    The most widely used system for the classification of viruses proposedby Lwoff et al. (1962) is based on the properties of the virion such as:

    <p>Type of nucleic acid; 2. Architecture or shape of the capsid; 3. Host range; 4. Size; 5. Site of synthesis in the host cell; 6. Presence or absence of a viral envelope; and 7. Means of its transmission.</p> Signup and view all the answers

    Double – stranded RNA viruse

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

    Double – stranded DNA viruses.

    <p>Herpes virus</p> Signup and view all the answers

    Single – stranded DNA viruses

    <p>Coliphage, Influenza virus.</p> Signup and view all the answers

    Single – stranded RNA+ viruses.

    <p>Tobacco Mosaic Virus, Picornavirus.</p> Signup and view all the answers

    Single – stranded RNA- viruses

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

    helical viruses (

    <p>Influenza virus</p> Signup and view all the answers

    -------- isthe spectrum of organisms a particular virus infects?

    <p>Host range</p> Signup and view all the answers

    ------- is determined largely by the presence of appropriate receptors on the host cell’s surface.

    <p>Host range</p> Signup and view all the answers

    Some viruses are as small as

    <p>2.5nm</p> Signup and view all the answers

    Other viruses are as large as?

    <p>300mm</p> Signup and view all the answers

    viruses range from about 1/10th to 1/3rd the size of a small bacterial cell

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

    In terms of simplicity, the largest virus contains only has how many genes while the smallest has how many?

    <p>77 genes,3 genes</p> Signup and view all the answers

    Largest virus

    <p>T4 virus</p> Signup and view all the answers

    Biggest virus

    <p>QB&amp; MS²</p> Signup and view all the answers

    Study Notes

    Viruses and Virology

    • The term "virus" comes from the Latin word for "venom" or "poison".
    • The discovery of viruses is attributed to Dmitri Ivanovsky in 1892, and the term "virus" was coined by Martinus Beijerinck in 1898.
    • Viruses are composed of genetic material (either DNA or RNA) and a protein coat surrounding the nucleic acid component.

    Characteristics of Viruses

    • Viruses are "an obligatory parasitic organism whose size is less than 200 micrometer" (described by Loeffler and Frosch).
    • A virus is a "sub-microscopic entity capable of being introduced into living cells and re-producing such cells" (defined by Bawden).
    • A virus is an entity whose genome is a nucleic acid (either DNA or RNA) that reproduces inside living cells and uses their synthetic machinery to direct its synthesis (defined by Luria and Darnell).
    • A virus is a "small infectious agent that can replicate only inside the living cells of an organism" (defined by Holmes).

    Study of Viruses

    • The study of viruses is called Virology, a branch of microbiology.
    • Approximately 2,000 viruses have been identified to date.

    Origin of Viruses

    • The origin of viruses is not fully understood or clear.
    • Pieces of DNA that can move between bacteria cells are known as transposons.
    • Viruses might have evolved from transposons or other genetic elements.

    Structure of Viruses

    • A virus is made up of three main parts: genetic material (either DNA or RNA), a protein coat (capsid), and a viral envelope (in some viruses).
    • The genetic material is located within the capsid.
    • The nucleic acid component of a virus contains the genome, which determines the properties of the virus and is the infectious part of the virus.
    • DNA or RNA molecules can be single-stranded or double-stranded.

    Types of Nucleic Acids

    • The base in DNA is called a nucleotide.
    • The base in RNA is called a nucleoside.
    • mRNA (messenger RNA) is a type of RNA that carries genetic information.

    Capsid and Viral Envelope

    • The protein coat surrounding the nucleic acid component of a virus is called the capsid.
    • The capsid is made up of small units called capsomers.
    • The capsid can be spherical, polyhedral, helical, or complex in shape.
    • The viral envelope is a thick, lipid bilayer membrane that covers the capsid in some viruses.
    • The viral envelope consists of lipids and proteins from the host cell and provides shape and rigidity to the virus.
    • Viruses with viral envelopes are called enveloped viruses, and those without are called naked viruses.
    • Some enveloped viruses have spikes that allow the virus to attach to its host cells.

    Enzymes

    • The first enzyme discovered was neuraminidase, followed by DNA-dependent RNA polymerase (transcriptase) and reverse transcriptase.
    • These enzymes are essential for infection and growth.

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