Molecular biology studies how various cellular components work together and interact at the molecular level, with a particular focus on DNA, RNA, and proteins. DNA stores genetic information in sequences of nucleotide bases (A, T, C, G). Through a process called transcription, this information is copied to RNA, which then undergoes translation to create proteins - the workhorses of cells that perform most biological functions. Key processes include: 1. DNA replication - making exact copies of genetic material before cell division 2. Gene expression - regulating when and how genes are turned on/off 3. Protein synthesis - assembling amino acids into functional proteins 4. Cell signaling - how cells communicate and respond to their environment Modern molecular biology techniques like PCR, gene sequencing, and CRISPR have revolutionized our understanding of genetics and enabled breakthroughs in medicine, biotechnology, and research.