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What is a gene?

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Quick answer

A gene is a segment of DNA that carries the instructions for building a specific protein or carrying out a function in the body. Genes are the basic units of heredity — passed from parents to offspring — and together they help shape an organism's traits.

Key things to understand

  1. A gene is a stretch of DNA with a coded sequence — the order of its bases A, T, C, and G.
  2. Most genes are recipes for proteins, the molecules that do the work in cells.
  3. You inherit two copies of most genes, one from each parent.
  4. Different versions of a gene (alleles) lead to variation, such as eye color.
  5. Genes are organized along chromosomes inside the cell's nucleus.

People also ask

How do genes determine traits?
A gene's DNA sequence is read to build a protein, and those proteins shape how the body develops and works — influencing traits like height or eye color, usually alongside the environment.
What is a mutation?
A change in a gene's DNA sequence. Some mutations have no effect, some cause disease, and some create the variation that fuels evolution.
Do genes control everything about me?
No. Genes set tendencies, but environment, behavior, and chance also shape most traits — nature and nurture work together.