The figure shows the restriction enzyme cutting sites `(R1-R3)` in wild type (n) and mutant (n) gene.

If a radioactively labelled probe (that hybridises at a sequence close to `R1)` is used for detecting the presence of DNA fragments after gel electrophoresis and Southern blotting, which of the following band patterns will yout expect ?
Note : L1 : wild type DNA, L2: mutant DNA

Options

A. (a)
B. (b)
C. (c)
D. (d)

Answer

C

Explanation

Restriction enzymes recongise the base sequence of palindrome sites in DNA duplex and cut is strands. After the cutting of DNA by restriction enzymes, fragments of DNA are formed. Separation of DNA fragments according to their size is done by gel electrophoresis. since the probe hybridises close to `R1` it will give 500 kb band for `L1` and 400 kb band for `L2` after gel electrophoresis.