Before we dive into gene expression, it’s important to understand the central dogma of molecular biology. This concept explains how genetic information flows inside a cell — from DNA to RNA to protein. It happens in two major steps:
- Transcription (DNA → RNA)
- Translation (RNA → Protein)
This can be summarized as:
Now, gene expression is the process by which the information encoded in a gene (a segment of DNA) is used to produce a functional product, typically a protein. In other words, gene expression is how a gene becomes “active” and performs its role in the cell.
Real-Life Example from the Lab:
Let’s say you’re working with a recombinant plasmid — a circular piece of DNA that you’ve engineered in the lab. Imagine this plasmid carries a gene from a virus that encodes a specific protein.
Here’s what happens:
- You insert this plasmid into mammalian cells using a method like transfection.
- The cells take up the plasmid, and the viral gene inside it is transcribed into mRNA.
- That mRNA is then translated into a protein by the cell’s ribosomes.
- The protein is now produced — this is gene expression in action.
And if that protein has a biological function (e.g. it triggers an immune response, or works as an enzyme), you’ve successfully expressed the gene functionally.
Summary:
Gene expression is the process where a gene’s DNA sequence is used to make a protein that performs a function in the cell. It’s essential for everything from basic cell survival to producing complex proteins in biotech and medical research.
Check out my expiCHO mammalian expression system protocol here