Discussion
Transformation in bacteria is the process by which
Answer: A
Correct answer: a cell takes up free DNA from its surroundings
Transformation is the uptake of naked DNA from the environment by a bacterial cell, which then incorporates it - usually by homologous recombination into the chromosome. It was demonstrated by Frederick Griffith in 1928, whose experiment showed that heat-killed virulent pneumococci could convert live avirulent ones into virulent form. The transforming principle was identified as DNA by Avery, MacLeod and McCarty in 1944, which was among the decisive pieces of evidence that DNA rather than protein carries heredity. A cell able to take up DNA is said to be competent. Competence arises naturally in species such as Streptococcus pneumoniae, Bacillus subtilis and Haemophilus influenzae, and can be induced artificially by treatment with calcium chloride followed by heat shock, or by electroporation - the methods on which routine cloning depends. The second option describes transduction.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development