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Introduction

Bacteria

  • Bacteria are single-celled microorganisms.
  • They exhibit a wide variety of shapes and structural features.
  • Bacteria can thrive in diverse environments, including the human body.
  • While many bacteria are harmless or even beneficial, some can cause infections in humans and are known as pathogenic bacteria.
  • Bacterial infections can lead to various diseases, and antibiotics are often used to treat bacterial infections.

Viruses

  • Viruses are even smaller than bacteria and are considered microscopic infectious agents.
  • They come in diverse shapes and sizes and can infect a wide range of organisms, including humans.
  • Viruses are obligate intracellular parasites, meaning they require a living host cell to replicate and reproduce.
  • Once inside a host cell, viruses hijack the cellular machinery to replicate and produce more virus particles.
  • Some viruses can damage or destroy host cells during the replication process, which can lead to diseases.
  • Vaccines and antiviral medications are used to prevent and treat viral infections.

Virus and Bacteria | Science & Technology for UPSC CSE

Viruses

  • Viruses are not classified as true living organisms because they lack cellular structures.
  • They are characterized by an inert crystalline structure outside a living cell.
  • Viruses are obligate parasites, meaning they depend on a host cell to replicate and reproduce, often causing harm or cell death.
  • The term "virus" was coined by Louis Pasteur and means "venom" or "poisonous fluid."
  • Viruses contain genetic material, which can be either RNA or DNA, but not both simultaneously.
  • Viruses that infect plants typically have single-stranded RNA, while those infecting animals may have single or double-stranded RNA or double-stranded DNA.
  • Bacteriophages, which infect bacteria, are typically double-stranded DNA viruses.
  • Viruses have a protective protein coat called a capsid, composed of smaller subunits known as capsomeres.
  • Capsomeres can be arranged in helical or polyhedral geometric forms depending on the virus.

Some examples of viral infections include

  • influenza
  • common cold
  • viral gastroenteritis
  • chickenpox
  • measles
  • viral meningitis
  • warts
  • human immunodeficiency virus (HIV)
  • viral hepatitis
  • Zika virus
  • West Nile virus
  • COVID-19 is another illness caused by a virus. This virus commonly causes:
    • shortness of breath
    • fever
    • dry cough

Bacteria

  • Bacteria are single-cell, living organisms capable of independent survival without a host.
  • They can thrive in various environments, including surfaces, soil, water, and air.
  • Antibiotics are effective in treating bacterial infections by targeting and killing bacteria. However, antibiotics do not work against viruses.
  • Some antiviral drugs can help prevent or manage viral infections by interfering with the virus's ability to enter host cells or reproduce.
  • Bacteria typically reproduce through a simple process of cell division, where one cell splits into two.
  • Bacterial infections can lead to various diseases, such as pneumonia and food poisoning.
  • It's essential to note that not all bacteria are harmful; some beneficial bacteria play crucial roles in protecting human health and aiding in various bodily functions.

Some examples of bacterial infections include

  • strep throat
  • urinary tract infection (UTI)
  • bacterial food poisoning
  • gonorrhea
  • tuberculosis
  • bacterial meningitis
  • cellulitis
  • Lyme disease
  • tetanus

Difference between Virus and Bacteria

Virus and Bacteria | Science & Technology for UPSC CSEVirus and Bacteria | Science & Technology for UPSC CSE

Virus and Bacteria | Science & Technology for UPSC CSE

Viroids

  • Viroids are infectious agents that are smaller than viruses, making them one of the simplest known pathogens.
  • Unlike viruses, viroids consist solely of a single, free RNA molecule and do not have a protective protein coat.
  • The term "viroid" is derived from the combination of "virus" and "RNA" due to their nature as small, infectious RNA molecules.
  • Viroids have a low molecular weight, as they are composed solely of RNA.
  • Viroids are known to cause diseases in various plants. One notable example is the "potato spindle tuber disease," which is caused by a viroid.

Virus and Bacteria | Science & Technology for UPSC CSE

Difference Between DNA & RNA Viruses

  • DNA Viruses:
    • Contain DNA as their genetic material.
    • Typically double-stranded.
    • Replicate in the nucleus of host cells.
    • Generally stable.
  • RNA Viruses:
    • Contain RNA as their genetic material.
    • Typically single-stranded.
    • Replicate in the cytoplasm of host cells.
    • Generally less stable and have a higher mutation rate than DNA viruses.
  • Antigens:
    • Substances recognized by the body as foreign, triggering an immune response.
  • Antibodies:
    • Blood proteins produced by the body in response to antigens, aiming to neutralize or eliminate them.

Difference between DNA vs RNA

Virus and Bacteria | Science & Technology for UPSC CSE

Difference between Gene & Genome

Virus and Bacteria | Science & Technology for UPSC CSE

The document Virus and Bacteria | Science & Technology for UPSC CSE is a part of the UPSC Course Science & Technology for UPSC CSE.
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