3.16) DNA and Genetic Information

Describe a DNA molecule as two strands coiled to form a double helix, the strands being linked by a series of paired bases: adenine (A) with thymine (T), and cytosine (C ) with guanine (G)

A chromosome is likely to contain thousands of genes. Taking one gene locus and expand the small section of chromosome will find the Double Helix shape, which appears to be parallels. 

The strand of the Double Helix are called the "Sugar-phosphate backbone." 

In the centre we find a group of molecules we called "bases" and there appears to be 4 different types of bases --- adenine (A), thymine (T), cytosine (C ), and guanine (G).

In the molecule these bases are holding together to the two helixes. They're held together by the following paired bases:

Adenine and Thymine

Guanine and Cytosine

They are called base pairs (nitrogenous bases). They're always found in DNA. 

Notice that the bases on one side of Helix have specific order: A, C, T, G, A, A, C, C, A, G.The order create up a gene. 

Gene is inside the nucleus, so the gene is defined as order of bases (ATGC) and the number of the bases. Both of them are important information for the construction of protein in the cytoplasm. It also gives the characteristic.
DNA molecules can also copy itself, which copies the genetic code exactly. This is important because to an extent they must copy and divide itself --- mitosis.