Chemical Structure of DNA:

DNA is made up of small units called nucleotides, and each nucleotide consists of three parts: 1. Phosphate group 2. Deoxyribose sugar (a five-carbon sugar) 3. Nitrogenous base, which can be one of four types: o Adenine (A) o Thymine (T) o Guanine (G) o Cytosine (C) Base Pairing Rules: • A always pairs with T (via two hydrogen bonds) • G always pairs with C (via three hydrogen bonds)

Double Helix Structure:

Discovered by Watson and Crick in 1953, DNA is composed of two strands coiled around each other like a twisted ladder. The nitrogenous bases form the "rungs" of the ladder, while the sugar-phosphate backbones form the sides.

Functions of DNA:

1. Storing genetic information – Instructions for building proteins. 2. Transmitting genetic information – Passed from one generation to the next. 3. Controlling biological processes – Such as growth, cell division, and reproduction. 4. Cell repair – Involved in correcting DNA damage or mutations.

Difference Between DNA and RNA:

Feature DNA RNA Sugar Deoxyribose Ribose Bases A, T, G, C A, U, G, C (Uracil instead of T) Structure Double-stranded helix Single-stranded Function Stores and transfers genetic info Copies and translates DNA instructions

How DNA Works:

1. Transcription: A specific part of the DNA is copied into RNA inside the nucleus. 2. Translation: The RNA carries this code to ribosomes, where proteins are assembled based on the genetic instructions.

🧫 Importance of DNA in Science and Medicine:

1. Genetic Testing: • Identifying inherited diseases. • Predicting risk for conditions like cancer and diabetes. 2. Forensic Science: • DNA fingerprinting is used to identify individuals in crime scenes. 3. Gene Therapy: • Altering or replacing faulty genes to treat diseases. 4. Genetic Engineering: • Modifying the DNA of organisms to produce medicines, improve crops, or cure genetic disorders.

The Human Genome Project:

• Started in 1990, completed in 2003. • Goal: Decode the entire human DNA sequence. • Outcome: Discovered over 20,000 human genes, improving our understanding of many genetic disorders.

Fascinating Facts About DNA:

• The human body contains around 3 billion base pairs of DNA. • If stretched out, the DNA in one human cell would measure about 2 meters (6.5 feet). • 99.9% of human DNA is identical across all people. • Only 0.1% makes each person unique.

Modern DNA Technologies:

1. CRISPR-Cas9: A revolutionary tool for editing genes precisely. 2. PCR (Polymerase Chain Reaction): A technique to quickly make many copies of a specific DNA segment. 3. DNA Sequencing: Determines the exact order of the bases in a DNA molecule.

Conclusion

DNA is not just a molecule—it is the biological foundation of life. It determines what we are, how we function, and how we inherit traits. Through DNA, science and medicine have made incredible progress, and it holds the key to curing many future diseases.