Bacterial Genetics Important Notes
1. Some important terms
2. Types of drug resistance
- Mutational drug resistance
- Transferable drug resistance
Bacterial Genetics Short Essays
Question 1. Methods of Genetic Transfer
Answer:
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:
Answer:
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
Answer:
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
Question 3. Plasmids
Answer:
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
- Restriction endonucleases are enzymes that cleave double-stranded DNA
- Southern blotting identifies DNA fragments
- Northern blotting analyses RNA
- Western blotting identifies antigens
- Pathogenicity is the ability of microbial species to produce disease
- Virulence is degree of Pathogenicity of microbe