What is the difference between genes and gene expression?

Your DNA consists of thousands of genes arranged on 23 different chromosomes.
A gene is a distinct sequence of nucleotides that codes for something.
Gene expression is the physical manifestation of that sequence of nucleotides in the human body.

For example, you may have gene ABC on one of your chromosomes. This gene will eventually be transcribed into RNA, which will then be translated into a protein. The protein will carry out some sort of function in the body. So this process of converting the gene into a protein and the protein carrying out a function is called gene expression.

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