class for reference: https://www.cs.colorado.edu/~main/edu/colorado/nodes/CharNode.java

Transcription: In the first step of protein synthesis, the 2 DNA strands in a gene that codes for a protein unzip from each other. Similar to the way DNA replicates itself, a single strand of messenger RNA (mRNA) is then made by pairing up mRNA bases with the exposed DNA nucleotide bases. For example:

DNA Sequence: C T G A A T

mRNA Sequence: G A C U U A

In other words, mRNA sequence can be produced from DNA sequence by replacing bases in the following manner. Base A is replaced with base U, base G is replaced with base C, base C is replaced with base G, base T is replaced with base A.

Task 3: Write a method that takes a DNA strand (a linked list of characters) and produces the corresponding mRNA sequence (a linked list of characters). The method should have one

parameter (CharNode) the head of a DNA strand, and return the head of the corresponding mRNA sequence (CharNode). The header of the method is the following:

public static CharNode dnaToRNA(CharNode dnaList)

If the value of the parameter is null then the method should return null. Your program should call this method and output the corresponding mRNA sequence.