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Genes, proteins, and traits

Review your understanding of genes, proteins, and traits in this free article aligned to NGSS standards.

Key points:

  • Genes are specific stretches of a chromosome’s DNA molecule. DNA molecules are made up of smaller parts called nucleotides. So, a gene is a specific stretch of nucleotides within a chromosome’s DNA.
  • DNA is made up of four types of nucleotides. These nucleotides are often called by their shortened names: A, C, T, and G (which stand for adenine, cytosine, thymine, and guanine). The nucleotides in a gene are connected in a specific order.
  • Proteins are molecules that carry out many different functions in cells. For example, some proteins provide structure for the cell. Others help carry out chemical reactions.
  • Proteins are made up of smaller parts called amino acids. The amino acids in a protein are also connected in a specific order. A protein’s amino acids determine its 3D structure and its function.
  • The cell builds proteins using instructions found in genes. Specifically, the order of nucleotides in a gene determines the order of amino acids in one or more proteins.
  • An organism has many different genes, and so can produce many different proteins. These proteins have functions that affect the organism’s traits.
A protein is shown as a globular, or lumpy ball-like, shape. Stretching out from the protein is a string of amino acids, which are represented as circles. Beneath four of the amino acids is a series of letters labeled nucleotides in a gene. An arrow points from the letters A C G to one of the amino acids. Other arrows point from the letters G G A, G C T, and G G A to different amino acids.
Proteins are made up of amino acids. The order of amino acids in a protein is determined by the order of nucleotides in its corresponding gene. Image created with Biorender.com.

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