Genes, Alleles, and the Genetic Code
From DNA to traits
What a gene is
A gene is a stretch of DNA that contains instructions for making a functional product, often a protein. Proteins help build structures and carry out many jobs in cells.
Alleles
An allele is a version of a gene. Different alleles can lead to different trait outcomes, such as different flower colors or blood type variants.
Key idea
Genes do not usually act alone. Most traits depend on many genes and on how those genes interact with each other and with the environment.
Gene terminology
| Term | Meaning |
|---|---|
| Gene | A DNA segment with a function |
| Allele | A version of a gene |
| Genotype | The allele combination an organism has |
| Phenotype | The observable trait |
What is an allele?
Alleles are alternative versions of the same gene.
Correct answer: A version of a gene
What is the difference between genotype and phenotype?
Genotype refers to the genetic makeup, while phenotype refers to what is expressed or observed.
Correct answer: Genotype is the allele combination; phenotype is the observable trait
How a gene can affect a trait
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1
Step 1: A gene is present in the DNA.
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2
Step 2: The gene is used to make a product, often a protein.
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3
Step 3: The protein helps perform a cell function.
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4
Step 4: That function contributes to a trait.
Which term means the observable trait?
Phenotype describes what can be seen or measured.
Correct answer: Phenotype