Question

Bacteriology

-What are the types of mutations and mutagens and explain them.

-define/explain transformation, conjugation, and transduction.

-Why is CRISPER used in the field of bacteria?

Answer 1

Answer-

According to the given question-

Question - 1

Mutation- is abrupt and sudden change in genetic material of an organisms and disrupt the normal functioning of the cell due to which DNA or chromosomes get affected

• Mutation can be
  • Hereditary mutations also called germline mutation in which the mutation are transferred from the parents to their germ cells and remain throughout the whole life.
  • somatic mutations also called acquired mutation- occur at a certain period of life in few cells of individuals due to exposure of ultraviolet radiation or due to some other factor which causes error in their DNA copy.

Mutations are classified as-

• Genetic mutation- of base leads to change in the reading frame that leads to change in the altered gene that are responsible for producing defected protein.  
  • Sunstitution- of one nitrogenous base with other
  • deletion - removal of nitogenous base
  • insertion - addition of nitrogenous base
• Chromosomal mutation- change in number of chromosomes causes defect in normal functioning of the body.
  • change in structure of chromosomes-
    • deletion- Deletion in part of chromosome-
    • duplication- insertion in part of chromosomes-
    • Inversion- when the two segment of same chromosomes get flipped and joined
    • Insertion- when some part of one chromosomes is break and inserted in other chromosome
    • Translocation- when segment from each chromosome gets interchanged
  • change in number of chromosomes- Aneuploidy
    • change in autosomes-
      • ​​​​​​​Downs syndrome - trisomy at chromosome number 21 leads to 47 chromosomes
    • ​​​​​​​​​​​​​​change in sex chromosomes
      • Klinefelter syndrome- additional sex chromosomes  X leads to XXY
      • Turner syndrome- female with one less sex chromosmes , have 45 chromosomes.

Mutagens- the factor that are responsible for alteration in gene.

• Physical mutagens
  • ionizing radiation- X -ray, cosmic rays, gamma rays,
  • non ionizing Radiation- UV light
• Chemical mutagens-
  • Base analogs- have same structure as DNA e.g. 5- bromouracil, 2-aminopurine
  • Intercalating agents- acridine orange ethidium bromide, proflavin
  • Reacting chemicals:- Nitrous acid
• Biological mutagens-
  • transposons
  • insertion sequence

Question- 2-

Transformation- the bacteria takes the foreign DNA from the environment or take naked DNA from solution.

Conjugation- the genetic material are transferred from one bacteria to other when both comes in contact with each other i.e. cell-to-cell contact.

Transduction- also a type of horizontal gene transfer where the DNA from one bacteria to the other bacteria is introduced with the help of viral vector.

Question- 3-

CRISPER- also called Clustered Regularly Interspaced Short Palindromic Repeats - consist of two components

• Cas9 - cut the DNA
• Guide RNA- recognize the sequence to be edited

genome that causing health problem was studied and they created a specific guide RNA that recognize particular stretch of nitrogenous bases in the DNA. then guide RNA attaches to the DNA cutting enzyme Cas9 and the complex is introduced to the target cell then it cuts the DNA and then scientist can edit the genome either by deleting or inserting new sequences and makes it cut and paste tool for DNA editing.

The bacteria are responsible of capturing part of  DNA from the viruses which invading them and they use that DNA and produce small part of DNA or DNA segments called  CRISPR arrays.

The CRISPR arrays helps in bacteria "remember" the invaded viruses or closely related viruses.