1-What is conjugation? Explain the mechanism of conjugation.
- What is transduction? Describe its mechanism.
- What is transformation? Give its mechanism.
1-What is conjugation? Is it a sexual mating?
Ans: The transfer of genetic material between bacteria through
cell-to-cell contact is called bacterial conjugation. Bacterial conjugation is often incorrectly regarded as sexual reproduction or mating It does not involve the fusion of gametes and formation of a zygote. Therefore, it is not actually sexual mating.
- What is episome ?
Ans: Episome is a plasmid of about 100 kh length that can integrate itself into the bacterial chromosome In genetic recombination. It carries its o\\11origin of replication, called (Il/I.
- What arc F+ and F-Bacteria?
Ans: There can only be one copy of the F-plasmid in a bacterium. Such bacterium is called F-positiveor sometimes male bacterium. The bacteria locking plasmic’ are called IL neuatix c or female bacterium.
- What is meant by low frequency of chromosomal gene
Ans: Some culture of cells contains non-integrated F-plasmic’s. These are responsible for the low-frequency of ‘chromosomal gene transfer.
- What is meant by Hfr
Ans: Some Strains of bacteria have integrated F-plasmid. Such
strains transfer chromosomal genes cry efficiently. So they are called Hfr (high frequency of recombination). A hfr cell is a bacterium with a conjugative plasmid (often /-) integrated into its genomic DNA. Unlike a normal F+ cell, hfr strains attempt to transfer their entire DNA through the mating bridges (called pili) to the F- cell.
- What is transduction? Who did discover it?
Ans: Transduction is the process by which bacterial DNA is moved from one bacterium to another by a virus. It was first discovered by Joshua Lederberg in 1952.
- Differentiate between generalized and specialized transduction.
Ans: Generalized transduction occurs in lytic cycle of phage virus. Specialized transduction occurs in Lysogenic cycle of phage – virus.
- What is Restricted transduction?
Ans: Certain phages cam out a more restricted kind of
Transduction. They carry only a specific section of bacterial genetic material. They transducer only a few genes. Retroviruses carry out specific or restricted transduction.
- What is transformation? Who did discover it?
Ans: Transformation is the genetic alteration of a cell resulting from the introduction, uptake and expression of foreign genetic material (DNA or RNA). It was discovered in 1928 Frederick Griffith.
10-What is meant by natural competence?
Ans: Natural bacterial transformation occurs only in bacterial species capable of natural competence. Such species carry sets of genes specifying machinery. It brings DNA across the cell’s membrane or membranes.
11-What is meant by artificial competence?
Ans: Artificial competence is not encoded in the cell’s genes. Instead it is a laboratory procedure. In this procedure, the cells are passively made permeable to DNA. These procedures are comparatively easy and simple. It can be used to genetically engineer bacteria.