A DNA molecule consists of 1600 hydrogen bonds in between nitrogen bases. It contains 200 adenine nucleotides. What is the length
of the DNA molecule?
1) 850 Å
2) 1020 Å
3) 4080 Å
4) 2040 Å
Answers
I hope this helps...
Given:
Total number of hydrogen bonds in DNA segment = 1600
Total number of adenine nucleotides = 200
To Find:
The length of the given DNA.
Solution:
Adenine form two hydrogen bonds with thymine.
And cytosine form three hydrogen bonds with guanine.
One adenine base forms = 2 hydrogen bonds
⇒ 200 adenine will form = 2 × 200 = 400 hydrogen bonds.
Now, total hydrogen bonds left = 1600 - 400 = 1200
And one cytosine form = 3 hydrogen bonds.
So, 1200 hydrogen bonds need = 1200/3 = 400 cytosine or guanine.
Total number of base pairs in one DNA strand = 200+ 400 = 800 bp
The distance between two consecutive basepairs = 3.4 A°
The length of the DNA = Total basepair in DNA× 3.4 angstrom
The length of the DNA molecule = 600 × 3.4 = 2040 angstrom.
Hence, the length of the DNA molecule is (2) 2040 angstrom.