Transfer of free DNA (? / R factor) takes
place across the bacteria by?
A. Conjugation
B. Transformation
C. Transduction
D. Transversion
Ans: B) Transformation
[By - Dr. Priyadarshi Hatekar, thanks...!!!]
Explanation -
Conjugation - plasmid mediated mating between
two bacteria which come in contact
Transformation -
direct uptake of naked DNA
fragments by recipient bacteria
Seen in Pneumococcus, Neisseria, Bacillus, H. influenzae
First describe by Griffith (1928) in Pneumococcus
He injected a mixture of live
noncapsulated strains type II (R) and
killed type I (S) strains of
pneumococcus into mice. Many mice died. He recovered
live capsulated pneumococcus from blood of mice that
died by cultures. i.e. In this experiment, a fragment of DNA
of killed type I strain was taken up by DNA of live rough
strain, resulting in synthesis of capusule
Can be done in vitro too with either plasmid or
chromosomal DNA
Transduction - infection of the bacteria
by a non-lethal virus(bacteriophage) carrying bacterial
genes
