Study Guides

Unit Summary

This unit covers the structure and function of eukaryotic and prokaryotic cells, DNA as the genetic material, and key genetic terms. It also explains protein synthesis, genetic variants, and how DNA structure affects proteins. The emphasis is on using models to explain scientific concepts.

Lesson Summary

You will learn to explain how a genetic variant in a gene can influence an organism's phenotype.

Key Notes

• When a mutation changes the sequence of nucleotide bases in a gene, this creates a genetic variant of the gene.
• If a triplet code in a gene is changed, this may or may not change the amino acid sequence in the protein that is made.
• A change in the amino acid sequence of a protein can change the 3D shape of the protein.
• A change in the 3D shape of a protein can change what it does (e.g. by changing the shape of an enzyme's active site).
• These changes can have impacts on an organism's phenotype.

Vocabulary To Learn

• gene: A gene is a section of DNA that holds the genetic code for a protein.
• genetic variant: A genetic variant is produced when a mutation causes a change in the genetic sequence of a gene or non-coding DNA.
• allele: A genetic variant in a gene creates an allele (a different version of the gene), which produces a different phenotype.
• triplet code: The triplet code is carried by genes. Each three nucleotide bases codes for a specific amino acid.
• phenotype: The phenotype is the physical characteristics of an organism.

Common Mistakes To Avoid

• Mutations always have a negative effect on an organism.

3 Quick Questions (With Answers)

More Lessons In This Unit

• Genetic variants in non-coding DNA can influence phenotype Study Guide
• Mutations and genetic variants Study Guide
• Protein synthesis Study Guide
• The chemical structure of DNA Study Guide
• The genetic code Study Guide
• The genome Study Guide
• The genome, the environment and phenotype Study Guide
• The structure of DNA Study Guide