(a) Self replication
(b) Information storage
(c) Stability
(d) Variation through mutation

a) Tobacco Mosaic Virus (TMV)
b) Bacteriophage \(\theta \)B

a) RNA was reactive and hence highly unstable.
b) Some RNA molecules acts as gene regulators by binding to DNA and affect gene expression.
c) Uracil of RNA is less stable than thymine of DNA.

a) Purine and pyrimidine bases are linked by hydrogen bonds.
b) Pentose sugar is linked to adjacent nucleotide by phosphodiester bonds.

The phosphate functional group (PO₄) gives DNA and RNA the property of an- acid at physiological pH, hence the name nucleic acid.

Adenine, Guanine, Cytosine and Uracil.

In eukaryotes, chromatin is formed by a series of repeating units called nucleosomes. It consists of a histone octamer. The negatively charged DNA is wrapped around the positively charged histone octamer to form a nucleosome.

The DNA as a nucleoid is organized into large loops held by protein. DNA of prokaryotes is almost circular and lacks chromatin organization, hence termed genophore.

The term 'RNA world' first used by Walter Gilbert 1986, hypothesizes RNA as the first genetic material on earth. There is now enough evidence to suggest that essential life processes (such as metabolism, translation, splicing etc.,) evolved around RNA. RNA has the ability to act as both genetic material and catalyst.

Erwin Chargaff changes observed that in DNA, Adenine pairs with Thymine (A = T) with two hydrogen bonds and Guanine pairs with Cytosine (G ☰ C) with three hydrogen bonds.
The ratios between Adenine with Thymine and Guanine with Cytosine are constant and equal. This base pairing gives a unique property to DNA.

In nucleic acids (DNA and RNA), the nitrogenous base is chemically linked to one molecule of sugar forming a nucleotide.
When a phosphate group is attached to the nucleoside, it becomes a nucleotide. The nucleotides are polymerised to form a polynucleotide chain (DNA and RNA).

The phosphate functional group (PO₄) present in DNA and RNA gives the property of an acid (releasing H⁺ ion or proton in solution) at physiological pH. Hence the name nucleic acid.