If an animal is homozygous null for a pair of genes, which term describes the animal's genetic modification?

If an animal is homozygous null for a pair of genes, which term describes the animal's genetic modification?

• A. Wild type
• B. Knockin
• C. Knockout
• D. Chimera

Answer: (C)

A knockout describes an organism in which a gene's function is completely disabled. When an animal is homozygous null for a gene, both copies are inactivated, making it a knockout for that gene. If two genes are affected in this way, it’s often described as a double knockout, but the modification is still characterized as a knockout. The other terms don’t fit here: wild type means no modification, a knockin involves inserting a gene or sequence into the genome, and a chimera is an organism with cells from more than one zygote.

A knockout describes an organism in which a gene's function is completely disabled. When an animal is homozygous null for a gene, both copies are inactivated, making it a knockout for that gene. If two genes are affected in this way, it’s often described as a double knockout, but the modification is still characterized as a knockout. The other terms don’t fit here: wild type means no modification, a knockin involves inserting a gene or sequence into the genome, and a chimera is an organism with cells from more than one zygote.