Study GuideBiology–Gene Expression (Molecular Genetics)1. DNA Defined1.1. A New Era in BiologyIn the 1950s, biology entered an exciting new phase. Scientists made rapid discoveries that helpedexplain how genes work inside cells. These breakthroughs led to the development ofmoleculargenetics, a field that focuses on how genetic information is used by living organisms.1.2 What Is DNA and Why Is It Important?At the center of molecular genetics isdeoxyribonucleic acid, better known asDNA. DNA is themolecule that stores all genetic information. This information determines how cells function and whattraits an organism inherits.DNA does not work alone. Instead, it passes instructions along in a step-by-step process that leads tothe production of proteins—the molecules that do most of the work in cells.1.3 From DNA to Protein: The Information PathwayThe flow of genetic information follows a clear sequence:DNA → mRNA → proteinHere’s how it works:•DNAholds the original genetic instructions.•These instructions are copied intomessenger RNA (mRNA).•mRNA then provides the code needed to buildproteins.This one-directional flow of information—from DNA to RNA to protein—is called theCentral Dogmaof molecular biology. It explains how genetic information is expressed in cells.Preview Mode
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