Bacterial Genetics Question And Answers

Bacterial Genetics Important Notes

1. Some important terms

Bacterial Genetics Some Important Terms

2. Types of drug resistance

  • Mutational drug resistance
  • Transferable drug resistance

Bacterial Genetics Short Essays

Question 1. Methods of Genetic Transfer

Gene transfer in bacteria occurs by following methods

  • Genetic Transformation
    • It is the transfer of genetic information through free or naked DNA
    • Factors influencing the transformation are
      • The physical state of donor DNA
      • Competency of the recipient cell
      • The fate of DNA upon entering the cell
    • It occurs naturally in Bacillus subtilis, Streptococcus pneumonia, Hemophilus influenza, Neis erria
    • It can be induced in the laboratory
  • Genetic Transfer Transduction
    • It is the transmission of a portion of DNA from one bacterium to another by a bacteriophage
    • A phage particle may carry a segment of host DNA besides its own nucleic acid
    • When this infects another bacterium DNA transfer is affected and the recipient cell acquires new characteristics coded by the donor DNA
    • It is not confined to transfer to chromosomal DNA
    • but can transfer episomes and plasmids
  • Genetic Transfer Significance
    • Widespread mechanism
    • Used for genetic mapping
    • Used In genetic engineering In the treatment of some Inborn errors of metabolism
  • Lysogenic conversion
    • In this method, a new genetic material Is Incorporated Into the bacterial chromosome known as prophage
    • This carries genetic Information to a bacterium which may code for new characteristics
    • The bacteria possessing this prophage is known as a lysogenic bacterium
  • Genetic Transfer Conjugation
    • The transfer of genetic information from one bacterium to another through matting is called conjugation
    • It takes place between a male cell that consists of F plasmid and a female cell which lacks F plasmid
    • The donor DNA combines with the recipient DNA resulting in genetic recombination

Bacterial Genetics Short Question And Answers

Question 1. Transfer factor:

Transfer factor

  • Transfer factor is a low molecular weight substance resistant to trypsin but gets inactivated at 56°C for 30 minutes.
  • It plays a role in the transfer of cell-mediated immune response in man.
  • It is not antigenic.
  • The transferred cell-mediated immune response is systemic and not local.
  • The mechanism of action is not known. But it may stimulate the release of lymphokines from sensitized T lymphocytes.

Transfer factor Uses:

  • Used in T cell deficiency (Wiskott Aldrich syndrome) patients.
  • Treatment of malignant melanoma and other type of cancer.
  • Used in the treatment of tuberculosis and lepromatous leprosy.

Read And Learn More: Microbiology Question and Answers

Question 2. DNA probes

DNA probes

DNA probes are radiolabelled or chromogenically labeled pieces of single-stranded DNA which can be used for the detection of homologous DNA by hybridization

DNA probes Advantages:

  • The high degree of specificity
  • Able to detect minute amounts of complementary DNA

DNA probes Use:

  • In clinical microbiology
  • Direct detection of microbes in specimens
  • To detect microbes which are either difficult or impossible to culture
    • Identification of culture isolates
    • Strain identification
    • To identify toxins, virulence factors
    • Identification of resistant markers

Bacterial Genetics The Classification Of Bacterial Replicons

Question 3. Plasmids


  • Plasmids are double-stranded circular DNA molecules present in the cytoplasm of bacteria
  • They are capable of autonomous replication
  • They are important vectors in genetic engineering
  • They are able to transfer genes from one bacterium to another
  • Two members of the same group of plasmids cannot occur in the same cells
  • They confer properties like toxigenicity and drug resistance

Bacterial Genetics Viva Voce

  1. Restriction endonucleases are enzymes that cleave double-stranded DNA
  2. Southern blotting identifies DNA fragments
  3. Northern blotting analyses RNA
  4. Western blotting identifies antigens
  5. Pathogenicity is the ability of microbial species to produce disease
  6. Virulence is degree of Pathogenicity of microbe

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