Homeotic Genes Contain a Homeobox Sequence That Is Highly Conserved

question 4

Multiple Choice

Homeotic genes contain a homeobox sequence that is highly conserved among very diverse species. The homeobox is the code for that domain of a protein that binds to DNA to regulate development of the embryo. The selective expression of homeotic genes, over time and space, is central to pattern formation during development. Based on this information, which of the following statements would you expect to be correct?

• A) Homeotic genes are selectively expressed over space and time during development.
• B) A homeobox-containing gene has to be a developmental regulator.
• C) Homeoboxes cannot be expressed in nonhomeotic genes.
• D) All organisms must have homeotic genes.

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Definitions:

Histone Tails

Histone tails are the N-terminal extensions of histone proteins that protrude from the nucleosome and play a key role in regulating gene expression by undergoing various chemical modifications.

Nucleosome

A basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around a core of histone proteins.

Transcriptionally Inactive

Refers to a state where certain genes or portions of the genome are not being transcribed into RNA, possibly due to regulatory mechanisms or chromatin structure.

Inducible Operon

A segment of DNA that includes genes which are transcribed together in response to an environmental signal.