Answer:
DNA strands consists of four nitrogenous bases, pentose sugar and a phosphate group. The DNA strands are complimentary with each other as thymine binds with adenine with two hydrogen bonds and guanine binds with cytosine with three hydrogen bonds.
The given DNA strand for cystic fibrosis is 5'......ATAGCAGAGCACCATTCTG.....3'. Its complimentary DNA strand in 3'......TATCGTCTCGTGGTAAGAC......5'. The DNA strands of 5'.....CAGAATGGTGCTCTGCTAT........3′. The dots before and after the given sequence represent that the given strand is a shirt stretch of the DNA made of large number of nucleotides.