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?

All of the above Signup and view all the answers

Who discovered whwt viruses are composed of?

Stanley Rendell 1935 Signup and view all the answers

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

Bawden (1943) 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.

Loria(1953) 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?

Luria and Darnell Signup and view all the answers

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

Koni et al (2006) Signup and view all the answers

Virsues are also called?

Viron Signup and view all the answers

Stydy of viruses is called Virology in the vranch if microbiology

True Signup and view all the answers

About how many viruses have been identified

1,000 Signup and view all the answers

Origin of viruses are know/ clear

False Signup and view all the answers

Pieces of DNA thatbcan move bacteria cells are know as?

Plasmids Signup and view all the answers

Viruses might have evolved from?

Plasmids and bacteria Signup and view all the answers

Viruses are at the - of life

Edge Signup and view all the answers

Visruses evolved from?

Plasmids and Bacteria Signup and view all the answers

Viruses are considered to be living organisms

True Signup and view all the answers

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

True Signup and view all the answers

A virus is made up of how many main parts?

W Signup and view all the answers

main parts of A vius are?

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

DNA

Deoxyribonucleic acis Signup and view all the answers

RNA

Ribonucleic acid Signup and view all the answers

Genetic material is located where?

Within the caspid Signup and view all the answers

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

Genetic materia/ genome/ Nucleiof Signup and view all the answers

Nucleic acid contains?

Pentonse,Phosphorosus,Nitrogen bases Signup and view all the answers

Genome in plant viruses is?

RNA Signup and view all the answers

Genome in Animal and bacterial viruses is?

DNA Signup and view all the answers

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

False Signup and view all the answers

DNA or RNA molecule may be

All of the above Signup and view all the answers

The base in DNA Is called?

Purine bases Signup and view all the answers

Tge base in RNA

Pyrimidine base Signup and view all the answers

mRNA

messanger RNA Signup and view all the answers

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

mRNA Signup and view all the answers

Types of Nucleic Acids in Virons

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

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

True Signup and view all the answers

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

Caspid Signup and view all the answers

Caspids is made up of small units called?

Capsometers Signup and view all the answers

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

Protometers Signup and view all the answers

Shapes of caspids?

Spherical,Helial,polyhedral,binal complex Signup and view all the answers

Which of the following is false about caspids

Contains codes for the synthesis of proteins and it own synthesis Signup and view all the answers

Which is an example of spherical or golf ball like

Influenza Signup and view all the answers

Polyhedral

Adenovirus Signup and view all the answers

Helical

Tobacco mosaic Signup and view all the answers

Complex

Bacteriophage Signup and view all the answers

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

10-18mm Signup and view all the answers

Amount of nucleic acid in a virys varies from?

1-50 percent Signup and view all the answers

Caspid is covered with a thick envelope called

Viral envelope Signup and view all the answers

Viral envelope consists of?

Proteins,lipids,and carbohydrates Signup and view all the answers

Viruses that have viral envelopes are called?

Enveloped viruses Signup and view all the answers

Viral envelope provides shape and ridigity found in viral envelopes

True Signup and view all the answers

Viruses without viral envelopes are called

Naked( Nucleopasid) virus Signup and view all the answers

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

True Signup and view all the answers

First Enzyme discorved was?

Neuraminidase Signup and view all the answers

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

Enzymes Signup and view all the answers

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

10-18mm Signup and view all the answers

neuraminidase is in?

in Influenza virus and Paramyxo viruses) Signup and view all the answers

DNA-dependent RNA is called

polymerase Signup and view all the answers

DNA-dependent RNA polymerase were detected in?

Vaccinia virus and several other animal, plant and insect viruses Signup and view all the answers

These enzymes are collectively called

transcriptases Signup and view all the answers

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

Transcriptases Signup and view all the answers

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

Reverse transcriptases Signup and view all the answers

A reverse transcriptase has been detected in RNA

Tumor virus Signup and view all the answers

Carbohydrates have been

True Signup and view all the answers

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

Lwoff et al. (1962) 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:

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. Signup and view all the answers

Double – stranded RNA viruse

Reovirus Signup and view all the answers

Double – stranded DNA viruses.

Herpes virus Signup and view all the answers

Single – stranded DNA viruses

Coliphage, Influenza virus. Signup and view all the answers

Single – stranded RNA+ viruses.

Tobacco Mosaic Virus, Picornavirus. Signup and view all the answers

Single – stranded RNA- viruses

Rhabdovirue Signup and view all the answers

helical viruses (

Influenza virus Signup and view all the answers

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

Host range Signup and view all the answers

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

Host range Signup and view all the answers

Some viruses are as small as

2.5nm Signup and view all the answers

Other viruses are as large as?

300mm Signup and view all the answers

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

True 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?

77 genes,3 genes Signup and view all the answers

Largest virus

T4 virus Signup and view all the answers

Biggest virus

QB& MS² 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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