Question

Identify the palindromic sequence in the following:
A. GAATTC/ CTTUUG
B. GGATCC/CCTAGG
C. CCTGG/GGACC
D. CGATA/GCTAA

Answer 1

Hint: Palindromic sequences are those which can be read from both the sides. For example: the word MALAYALAM can be read from either side i.e from the left side as well as from the right side. Same goes for the nitrogenous bases.

Complete answer:
To solve the given question, we must be well aware of the base sequence.

DNA as we all know is made up of nitrogenous bases, phosphate group and ribose sugar. The two strands of DNA run from 3’ to 5’ and from 5’ to 3’ coil around each other to form the double helical structure of the DNA or the RNA.
There is a specific sequence of the nitrogenous bases on both these strands. Now when the sequences are the same when we read them from either side, then it is known as palindromic.
 Let's understand this further.
We all know that each DNA strand is read from 3’ to 5’. But when it reads exactly the same from 5’ to 3’ then the sequence will be called a palindromic sequence.

Therefore, the correct answer to the question is GGATCC/CCTAGG.

Note: It must be noted here that the restriction endonucleases recognizes these palindromic sequences. Here it must also be noted that Adenine pairs with Thymine and Guanine pairs with Cytosine and vice-versa. Further, in RNA Thymine is replaced by Uracil and now Adenine pairs with Uracil.