Question

Clear area 6. Inducing Mutation: a. Define mutation b. How is mutation different from conjugation? c. What are plasmids? d. Source of mutation e. Different types of nitrogenous bases in DNA f. Phenotype of wild strain of bacteria g. Phenotype of mutant colonies h. Effect of UV exposure on Serratia? "Whitesh in color Da ncased in a di de sea in

Answer 1

6, a Mutation is a change in the DNA sequence due to error in addition of nucleotides either naturally or by inducers (physical or chemical ) which cannot be reverted back by the repair systems. The change gets inherited in the DNA.

b, Mutation is the change in the sequence of DNA which is relatively slow and induced either by error prone repair mechanisms or by artificial inducers- chemicals, radiation exposure, etc which can be either beneficial or harmful whereas conjugation is a type of horizontal gene transfer where large sequences of DNA are passed from a donor bacterium to the recepient bacterium rapidly. It ends up in rapid changes such as resistance to antibiotics and rapid adaptability to the environment.

c, Plasmids are double stranded, circular, self replicating extra chromosomal DNA naturally present in the bacteria. Plasmids render extra functions to the bacetrial cell such as antibiotic resistance, virulence, etc. they can be transferred from one bacteria to another through conjugation.

d, Mutation can be either spontaneous or artificially induced.

Spontaneous mutation is due to error in the replication process. Error prone repair mechanism can lead to mutation which is a source of variation and evolution. Mostly point mutation happen spontaneously. It can be due to tautomeric shifts, wobble basepairing, chemical changes-depurination, deamination,etc

Induced mutation are due to substances called as mutagens. It can be due to base analogs (ex- 5-bromouracil), radiation exposure (UV), intercalating agents (EtBr), alkylating agents (ethylmethylsulphonate), etc

e, The different types of nitrogenous bases in DNA are double ringed purines and single ringed pyrimidines. Purines include Adenine and Guanine whereas Pyrimidines include Cytosine and Thymine