Genes work through proteins

The idea

Genes control traits through the proteins they code for: if a gene is altered so that its enzyme works less efficiently, less of that enzyme's product is made and the trait changes.

Why is a plant short?

A plant hormone triggers plant growth. An enzyme helps the plant to make that hormone. The enzyme is made using the information in a gene.

If the gene for the enzyme has an alteration so that the enzyme works less efficiently, what happens to the plant?

• It makes less hormone and grows short
• It makes more hormone and grows tall
• Nothing changes

Alter the gene

Press the buttons and watch the enzyme, the hormone and the plant.

From gene to trait

The gene gives the information for the enzyme. An enzyme that works less efficiently gives less hormone, so the plant is short. In this way genes control traits.

Genes control traits through the proteins they code for. If a gene is altered so that its enzyme works less efficiently, less of the enzyme's product is made and the trait changes.

Notes

Genes control traits through the proteins they code for: an altered gene can make an enzyme less efficient, so less product is made and the trait changes.

Check yourself

A gene has an alteration that makes its enzyme less efficient. What happens in the plant height example?

Which chain is correct for the plant height example?

A change in a gene can change a trait because it can change…

• More hormone is made and the plant is tall. A less efficient enzyme makes less of the hormone, not more.
• The same amount of hormone is made and the height stays the same. If the enzyme works less efficiently, the amount of hormone made is less, so the height changes.
• Less hormone is made and the plant is short — correct. Yes!
• Efficient enzyme, a lot of hormone, tall plant — correct. Yes!
• Efficient enzyme, less hormone, tall plant. If the enzyme works efficiently, a lot of hormone is made.
• Less efficient enzyme, a lot of hormone, short plant. If the enzyme is less efficient, the amount of hormone is less.
• the number of genes the plant has to count. In the example, the alteration makes the enzyme less efficient, so less of its product is made.
• how efficiently a protein such as an enzyme works — correct. Yes!
• which parent the gene came from. In the example, the alteration makes the enzyme less efficient, so less of its product is made.