Introduction

Genetics is the study of heredity and variation in living organisms. At the heart of genetics lies DNA (Deoxyribonucleic Acid), the molecule that carries the instructions for life. Understanding DNA and genetics is essential for biology students, as it explains how traits are passed from one generation to the next.

DNA Structure

1. Double Helix: DNA is shaped like a twisted ladder.
2. Nucleotides: The building blocks of DNA, consisting of:
3. Sugar (deoxyribose)
4. Phosphate group
5. Nitrogen bases (Adenine, Thymine, Cytosine, Guanine)
6. Base Pairing:
7. Adenine (A) pairs with Thymine (T)
8. Cytosine (C) pairs with Guanine (G)

Genes and Chromosomes

1. Genes: Segments of DNA that code for proteins.
2. Chromosomes: Long strands of DNA tightly coiled around proteins. Humans have 46 chromosomes (23 pairs).
3. Alleles: Different versions of a gene that determine variations in traits.

DNA Replication

1. DNA copies itself before cell division.
2. The double helix unwinds, and each strand serves as a template for a new complementary strand.
3. This ensures genetic information is passed accurately to new cells.

The Genetic Code

1. DNA sequences are read in groups of three bases called codons.
2. Each codon corresponds to a specific amino acid.
3. Proteins are built from these amino acids, carrying out vital functions in the body.

Applications of Genetics

1. Medicine: Understanding genetic disorders and developing treatments.
2. Agriculture: Creating disease‑resistant crops.
3. Forensics: DNA profiling helps solve crimes.
4. Biotechnology: Genetic engineering and cloning.

Summary

Genetics and DNA form the blueprint of life. By studying DNA structure, replication, and the genetic code, students gain insight into how traits are inherited and how modern science uses genetics to improve health, agriculture, and technology.