This lesson introduces Hox genes, their role in arranging body structures, and the proteins they produce. Understanding this distinction helps explain how an embryo develops the right structures in the right locations.
Hox genes are a subset of homeobox genes that help specify regions of an animal's body plan along the head-to-tail, or anterior-posterior, axis. They provide cells with information about where they are in the body. This positional identity helps determine which structures develop at each location.
All flashcards
What is a Hox gene?
A member of the homeobox gene family that helps specify positional identity and body-region characteristics along an animal's head-to-tail axis.
What is positional identity?
Developmental information that helps cells and tissues acquire characteristics appropriate to their location in the body.
How do Hox genes differ from all homeobox genes?
Hox genes are only one subset of homeobox genes. A gene can contain a homeobox without being a Hox gene.
What does a Hox protein do?
It acts as a transcription factor, binding regulatory DNA and activating or repressing other genes involved in development.
What is the homeodomain?
A 60-amino-acid DNA-binding domain encoded by the homeobox. It folds into a helix-turn-helix structure that helps a Hox protein bind DNA.
Quiz questions
What does colinearity describe in many animals with clustered Hox genes?Answer: Gene order in a cluster corresponds to expression order along the anterior-posterior axis.
In Drosophila, what can happen when Antennapedia is expressed in antennal imaginal tissue?Answer: The tissue can adopt leg identity, producing a leg in place of an antenna.
How are human Hox genes organized?Answer: Thirty-nine genes are organized into four clusters: Hoxa, Hoxb, Hoxc, and Hoxd.
What role do HOX10 genes play in mouse lower-back development?Answer: Their activity helps prevent ribs from forming on lower-back vertebrae.
How can the cofactors Extradenticle and Homothorax affect Hox protein activity?Answer: They bind Hox proteins and can improve specificity for target DNA sites.
Based on the Wikipedia article Hox gene, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.