Question

Complete each statement.

Answer 1

7. Adenine (A), Guanine, Cytosine and Thymine are the four nitrogenous bases in DNA.

8. In DNA Cytosine always forms hydrogen bonds with guanine.

9. The sequence of nucleotides carries the genetic information of an organism.

10. The process of replication produces a new copy of an organism's genetic information which is passed on to a new cell.

11. The double-coiled shape of DNA is called a double helix

Explanation:

There are four nitrogenous bases in the DNA of an organism. Two of the bases are pyrimidines eg: Thymine and cytosine while 2 of the bases are purine  bases namely adenine and guanine. The purine of one strand forms a hydrogen bond with pyrimidine of the parallel strand of DNA.

The bases are present in nucleoplasm as dNMPs and in DNA they are present as dNTPs (deoxyribonucleotide triphosphate). During replication, these dNMPS keeps on bonding with other dNMPs in the presence of ATP and as DNA Polymerase, ligase topoisomerase etc. These nucleotides form the DNA strands and they are responsible for coding proteins. The sequence of DNA is also termed as gene.

The double helix structure of DNA was given by Watson and Crick. Each strand has an alternative backbone of sugar and phosphate group. The four bases bonds with glycosidic and phosphodiester bonds with sugar and phosphoric acid.