When Genes Change: Mutations and Proteins
Aligned to MS-LS3-1 — Next Generation Science Standards.
What this lesson teaches
Genes carry instructions for building proteins, which shape an organism's traits. A structural change to a gene, called a mutation, can change the protein it makes — and that change may be harmful, beneficial, or have no effect at all.
Worked examples
Example 1
A mutation in the gene for skin pigment can stop a protein from forming color, producing an animal with no pigment; the same kind of change in a different gene might do nothing, showing mutations can be harmful, neutral, or occasionally helpful.
Example 2
Most mutations do nothing at all, because they land in stretches of DNA that do not code for a protein.
Example 3
A mutation harmful in one environment can help in another. Sickle-cell carriers face risks, and also resist malaria.
Practice questions
- Copy a short sentence by hand and see how changing one letter changes the meaning, like a mutation.
- Model a gene as a bead string, swap one bead, and describe how the built protein might change.
- Explain, using your model, why some mutations are harmful, some are neutral, and some are beneficial.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Cuando los genes cambian: mutaciones y proteínas
Los genes llevan instrucciones para construir proteínas, que dan forma a los rasgos de un organismo. Un cambio en la estructura de un gen, llamado mutación, puede cambiar la proteína que produce — y ese cambio puede ser perjudicial, beneficioso o no tener ningún efecto.
Ejemplo 1: Una mutación en el gen del pigmento de la piel puede impedir que una proteína forme color, produciendo un animal sin pigmento; el mismo tipo de cambio en otro gen podría no hacer nada, mostrando que las mutaciones pueden ser perjudiciales, neutrales u ocasionalmente útiles.
Ejemplo 2: La mayoría de las mutaciones no hacen nada, porque caen en tramos de ADN que no codifican una proteína.
Ejemplo 3: Una mutación dañina en un ambiente puede ayudar en otro. Los portadores de células falciformes enfrentan riesgos y también resisten la malaria.
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