DNA Structure and Components

The DNA molecule is a complex structure that serves as the blueprint for life. Located in the nucleus of eukaryotic cells and the cytoplasm of prokaryotic cells, DNA carries genetic information through its unique structural arrangement.

Definition: DNA (deoxyribonucleic acid) is a nucleic acid that contains the genetic instructions for the development and functioning of living organisms.

Vocabulary: Nucleotides are the building blocks (monomers) of DNA, consisting of three components: a phosphate group, deoxyribose sugar, and a nitrogen base.

The backbone of DNA is formed by alternating phosphate groups and deoxyribose sugar molecules. The structure features four different nitrogen bases divided into two categories:

Example: Purines (larger bases):

• Adenine (A)
• Guanine (G) Pyrimidines (smaller bases):
• Cytosine (C)
• Thymine (T)

Highlight: The base-pairing rules are fundamental to DNA structure:

• Adenine always pairs with Thymine
• Cytosine always pairs with Guanine These pairs are held together by hydrogen bonds.

Quote: "The rungs/steps of the DNA molecule is composed of nitrogen bases."

The double helix structure of DNA is maintained by these specific base-pairing rules and the sugar-phosphate backbone, creating a stable and reliable storage system for genetic information.