Question

Describe the structure of the DNA molecule. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> [Textbook question 3b pg no.193]

Answer 1

Answer

Structure of DNA is a double helix, human DNA has around 3 billion bases and more than 99% of those bases are the same for all.

DNA sequencing is used to allow researchers to determine the order of bases in the DNA sequence, order or bases in genes, chromosomes or an entire genome.

The basic structure of DNA:

• The backbone of nucleic acids or DNA is nucleotides. There are three components of nucleotides

1. A five-carbon sugar called deoxyribose sugar.
2. A phosphate group.
3. A nitrogenous base – It is a nitrogen-containing ring structure that allows complementary base pairing.

• The carbon atoms of five carbon deoxyribose one numbered 1’,2’,3’,4’and 5’
• A nucleotide comprises the five-carbon sugar and nitrogenous bases. The nitrogenous bases adenine(A), guanine (G) are called purines. Purines have a double-ring structure with a six-carbon ring fused to a five-carbon ring. Nitrogenous bases cytosine (C) and the thymine (T) are called Pyrimidines, these are nitrogenous bases having a six-carbon ring structure.
• Nucleoside triphosphate is combined with each other by phosphodiester bonds where phosphate group attached to 5’ carbon of sugar of one nucleotide bonds to the hydroxyl group of the 3’ carbon of sugar of next nucleotide.