Question

The base sequence in one of the strands of DNA is TAGCATGAT.
A. Give the base sequence of its complementary strand.
B. How are these base pairs held together in a DNA molecule?
C. Explain the base complementary rule. Name the scientist who framed this rule.

Answer 1

Hint: DNA is double stranded genetic material. It consists of sugar, phosphate groups, and nitrogenous bases. Bases are complementary in both the strands of the DNA. Purins (A and G) form hydrogen bonds with pyrimidines (T and C). The amount of purines is equal to pyrimidines.

Complete answer:
A. DNA (deoxyribonucleic acid) is a hereditary material of the organisms. It is formed by sugar (deoxy-ribose), phosphate groups and four types of nitrogen bases. Nucleic acid base pairs bind together with the hydrogen bond. The nucleic acid bases of two nucleotides are complementary to each other that are A-T, G-C. So, the complementary base of DNA sequence ‘TAGCATGAT’ will be ‘ATCGTACTA’.

B. The base pairs of DNA are held together by the hydrogen bond. Adenine is bounded by double bonds with thymine while cytosine and guanine bind together by three hydrogen bonds.

C. Chargaff’s rule is also called the base pairing rule. It is named after scientists who observed that there are equal molar concentrations of A and T as G and C in most DNA molecules from Columbia University.
Pairing of base pairs occur in following manner:
T with A : the pyrimidine thymine (T) always pairs with purine adenine(A)
G with C : the purine guanine (G) always pairs with pyrimidine cytosine (C)
Purine always pairs with pyrimidine. This rule is given by a scientist named Erwin Chargaff.
The rules of base pairing also tell us that the amount of adenine is equal to the amount of thymine. Similarly, the amount of guanine is equal to the amount of cytosine. A=T and G=C.

Note: Adenine, Uracil, cytosine, and guanine are the Nitrogenous bases that are present in RNA. Instead of thymine uracil is present. RNA is single stranded and unstable genetic material. DNA binds on the histone protein and this structure is called a nucleosome. Replication of DNA is the process of forming complementary strands.