A gene is defined as:

A gene is defined as:

• A. A portion of DNA that identifies how traits are expressed and passed down; all genes form genotype
• B. A type of protein
• C. A segment of RNA
• D. A chromosome that carries multiple genes

Answer: (A)

A gene is a specific sequence of DNA that carries the instructions to make a molecule—usually a protein or a functional RNA—that influences a trait and can be inherited. Genes are the basic units of heredity, and the collection of all genes an organism has makes up its genotype. This is why the option describes a portion of DNA that identifies how traits are expressed and passed down and notes that all genes together form the genotype. Proteins are the products that some genes code for, not the unit itself, so calling a gene “a type of protein” isn’t accurate. A segment of RNA isn’t the gene in most organisms, since genes are defined by their DNA sequence (though some genes code directly for RNA). A chromosome carries many genes, rather than being a single gene itself.

A gene is a specific sequence of DNA that carries the instructions to make a molecule—usually a protein or a functional RNA—that influences a trait and can be inherited. Genes are the basic units of heredity, and the collection of all genes an organism has makes up its genotype. This is why the option describes a portion of DNA that identifies how traits are expressed and passed down and notes that all genes together form the genotype.

Proteins are the products that some genes code for, not the unit itself, so calling a gene “a type of protein” isn’t accurate. A segment of RNA isn’t the gene in most organisms, since genes are defined by their DNA sequence (though some genes code directly for RNA). A chromosome carries many genes, rather than being a single gene itself.