Biochemistry Paper 03 - Module 08 Quiz
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Questions and Answers

What does the term 'virus' mean in Latin?

poison

What are the two main components of a virion?

Genetic material and protein coat

What is the name given to the protein coat that surrounds the nucleic acid in a virus?

capsid

What is the term for the complete entity of nucleic acid packaged inside the protein coat?

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

What is the name of the field that studies viruses?

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

Which of the following are considered the main characteristics used for virus classification?

<p>Phenotypic characteristics, nucleic acid present, mode of replication, host organisms, and the type of disease caused. (A)</p> Signup and view all the answers

What are the two main classification schemes used for viruses?

<p>ICTV system and Baltimore classification system</p> Signup and view all the answers

Which of these is a defining feature of the ICTV classification system?

<p>Utilizes phenotypic characteristics and the type of disease caused by the virus. (D)</p> Signup and view all the answers

What is the basis of the Baltimore classification system?

<p>The nucleic acid present in viruses</p> Signup and view all the answers

How many groups are viruses categorized into within the Baltimore classification system?

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

DNA viruses typically replicate inside the nucleus of the cell.

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

RNA viruses replicate in the cytoplasm of the cell.

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

RNA viruses tend to mutate faster than DNA viruses.

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

What are the four main stages of viral replication?

<p>Attachment, penetration, synthesis, assembly and maturation, and release</p> Signup and view all the answers

What is the name of the process by which a virus binds to a specific receptor on a host cell?

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

What process follows attachment, where the virus enters the host cell?

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

What is the name of the stage where the virus uses host cell machinery to produce new viral particles?

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

What are the two categories of proteins produced during the synthesis stage?

<p>Early proteins and late proteins</p> Signup and view all the answers

What are the two main processes involved in viral particle formation?

<p>Assembly and maturation</p> Signup and view all the answers

What are the two main ways viruses can be released from a host cell?

<p>Budding and lysis</p> Signup and view all the answers

What are the two main life cycles of a bacteriophage?

<p>Lysogenic cycle and lytic cycle</p> Signup and view all the answers

Viroids are sub-viral pathogens that lack a protein coat.

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

Prions are made entirely of protein and lack DNA or RNA.

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

What is the name of the protein that prions are derived from?

<p>Prion protein (PrP)</p> Signup and view all the answers

Flashcards

What are viruses?

Acellular entities that consist of either DNA or RNA as their genetic material, enclosed in a protein coat, and rely on a host cell for replication.

What is Virology?

The study of viruses, encompassing their structure, function, replication and interactions with host organisms.

What is a capsid?

The protein shell surrounding a virus's nucleic acid.

What is a capsomere?

Individual protein subunits that assemble to form the capsid.

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What is a nucleocapsid?

The complex structure formed by the nucleic acid and its surrounding capsid.

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What is a virion?

A complete virus particle, ready for infection.

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What are enveloped viruses?

Viruses with an outer membrane composed of lipids, typically spherical in shape.

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What are helical viruses?

Viruses with a hollow protein cylinder shape.

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What are complex viruses?

Viruses with complex, often asymmetrical structures.

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What is virus classification?

The process of assigning viruses to taxonomic groups based on shared characteristics.

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What is a virus species?

A monophyletic group of viruses with distinct properties, defined by multiple criteria.

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What is the Baltimore Classification System?

The classification system that groups viruses based on their nucleic acid type, strandedness, and replication strategy.

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What is the ICTV classification system?

The classification system that uses phenotypic characteristics, such as morphology, nucleic acid, and host range, to group viruses.

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What are dsDNA viruses?

Viruses that use double-stranded DNA as their genetic material and replicate using DNA-dependent DNA polymerase.

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What are ssDNA viruses?

Viruses that use single-stranded DNA as their genetic material and create a double-stranded DNA intermediate during replication.

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What are dsRNA viruses?

Viruses that use double-stranded RNA as their genetic material.

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What are ssRNA Plus strand viruses?

Viruses that use single-stranded positive-sense RNA as their genetic material, which can directly act as mRNA.

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What are ssRNA Minus strand viruses?

Viruses that use single-stranded negative-sense RNA as their genetic material, requiring a viral enzyme to generate mRNA.

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What are reverse transcribing viruses?

Viruses that use RNA as their genetic material and integrate a DNA copy into the host genome using reverse transcriptase.

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What are pararetroviruses?

Viruses that replicate using an RNA intermediate, but are not considered true DNA viruses.

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What is viral attachment?

The process by which a virus attaches to and enters a host cell.

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What is viral penetration?

The process by which a virus releases its genetic material into the host cell's cytoplasm.

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What is viral synthesis?

The step in viral replication where the virus directs the host cell's machinery to synthesize viral nucleic acids and proteins.

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What is viral assembly?

The process by which viral components are assembled into mature virions.

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What is viral release?

The release of newly formed virions from the host cell.

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What is the lysogenic cycle?

A viral life cycle where the virus integrates its genetic material into the host's genome, replicating along with the host cell.

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What is the lytic cycle?

A viral life cycle where the virus replicates rapidly within the host cell, eventually leading to cell lysis.

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What are viroids?

Non-coding, circular single-stranded RNA molecules that infect plants, lacking a protein coat.

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What are prions?

Infectious agents composed solely of protein, lacking any DNA or RNA, that cause conformational changes in normal proteins.

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Study Notes

Course Information

  • Subject: Biochemistry
  • Paper: 03
  • Module: 08
  • Topic: Structure and Function of Biomolecules II (DNA and RNA Viruses)

Principal Investigators and Coordinators

  • Principal Investigator: Dr. Sunil Kumar Khare, Professor, Department of Chemistry, IIT-Delhi
  • Paper Coordinator and Content Writer: Dr. Sunil Kumar Khare, Professor, Department of Chemistry, IIT-Delhi & Prof. M.N. Gupta, Department of Biochemical Engineering and Biotechnology, IIT-Delhi
  • Content Reviewer: Dr. Arun Goyal, Professor, Department of Biotechnology, Indian Institute of Technology Guwahati, North Guwahati, 781 039 Assam, India

Objectives

  • Understand viruses and their classification
  • Learn about DNA and RNA viruses
  • Explore how viruses infect and replicate in a host
  • Examine virus-like particles (e.g., viroids and prions)

Concept Map

  • Viral Class: DNA Viruses and RNA Viruses
  • Viral Genome: single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), single-stranded RNA (ssRNA), double-stranded RNA (dsRNA)

Description and Introduction

  • Viruses are pseudo-living particles with some chemical similarities to living cells.
  • They are contagious agents causing various deadly diseases (e.g., smallpox, influenza, yellow fever).
  • Viruses are submicroscopic acellular entities composed of DNA or RNA with a protein coat.
  • They are obligate intracellular parasites that replicate only within a suitable host.
  • Viruses have a period outside the host cell, existing in an extra-cellular form.
  • Viruses utilize the host's machinery for replication, transcription, and protein synthesis.
  • Virology is the study of viruses.

History of Viruses

  • Viral diseases have been known for a long time, even before the exact cause was known.
  • Variolation or vaccination (inoculation with attenuated viruses) was popularized by Edward Jenner in 1798.
  • Dmitri Ivanovski demonstrated that sap from infected plants, even after filtering out bacteria, could still cause infection, implying the existence of a filterable virus.
  • Martinus Beijerinck discovered that a causative agent smaller than bacteria was responsible for the disease.
  • Development of electron microscopy and other techniques enabled detailed observation.

Viral Structures

  • Viruses come in various shapes and sizes (30-400 nm).
  • Their structure includes a nucleic acid core (DNA or RNA) enclosed within a protein coat (capsid).
  • Capsids are composed of repetitive protein subunits called capsomeres.
  • Some viruses have an outer envelope derived from the host cell membrane.
  • These structures (nucleocapsids) are mostly symmetrical in shape.

Viral Classification

  • There are four types of virion structure: icosahedral, helical, enveloped, and complex.
  • Various classification systems exist, such as the Baltimore classification (based on viral nucleic acid and replication strategies) using a system with seven classes of virus organisms.
  • The International Committee on Taxonomy of Viruses (ICTV) defines species in terms of viral properties.

DNA and RNA Viruses

  • DNA viruses replicate within the nucleus, generally using cellular enzymes, have a low mutation rate and often cause chronic infections.
  • RNA viruses mostly replicate in the cytoplasm, with a high mutation rate. Their replication often involves unique enzymes and mechanisms.

Viroids and Prions

  • Viroids are sub-viral pathogens that infect plants and are composed of small, naked RNA molecules.
  • Prions are infectious agents composed solely of protein. They can cause neurological diseases by converting normal proteins to abnormal forms.

Viral Replication

  • Viruses attach to host cells and penetrate them, releasing their genetic material.
  • The virus's genetic material takes over the host cellular machinery.
  • New viral components are synthesized, assembled, and released to infect other cells.

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DNA RNA Viruses PDF

Description

Test your understanding of the structure and function of DNA and RNA viruses in this quiz for Biochemistry Paper 03, Module 08. The quiz covers virus classification, infection mechanisms, and related concepts like viroids and prions. Challenge yourself to grasp the complexities of viral biology!

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