What is the function of a Hox gene?

HOX genes are a family of regulatory genes that encode transcription factors and are essential during embryonic development. These genes are highly conserved between species such that all metazoans possess a common genetic system for embryonic patterning.

What is the effect of most mutations on organisms?

When mutations occur they can cause termination (death) of an organism or they can be partially lethal. This means that the organism has difficulty adapting to and surviving in its environment. Mutations are usually the cause of many diseases and defects in an organism’s life.

Are Hox genes only in vertebrates?

The protein product of each Hox gene is a transcription factor. Each Hox gene contains a well-conserved DNA sequence known as the homeobox, of which the term “Hox” was originally a contraction….Vertebrates.

How is the lac operon regulated?

Two regulators turn the operon “on” and “off” in response to lactose and glucose levels: the lac repressor and catabolite activator protein (CAP). The lac repressor acts as a lactose sensor. It normally blocks transcription of the operon, but stops acting as a repressor when lactose is present.

What is a homeotic mutant?

Mutations in homeotic genes cause displaced body parts (homeosis), such as antennae growing at the posterior of the fly instead of at the head. Mutations that lead to development of ectopic structures are usually lethal.

What’s the difference between Homeotic and homeobox genes?

The main difference between homeobox homeotic and hox genes is that homeobox is a specific DNA sequence found within homeotic genes while homeotic genes are the genes responsible for the regulation of the patterns of anatomical development in animals, plants, fungi, and some unicellular eukaryotes, and Hox genes are a …

What happens to the second leg of the antenna?

Antennapedia. Loss-of-function mutations in the regulatory region of this gene result in the development of the second leg pair into ectopic antennae. By contrast gain-of-function alleles convert antennae into ectopic legs.

What kind of mutations are found in Antennapedia?

The mutation Antennapedia. Antennapedia (abbreviated Antp) is a HOM-C gene first discovered in Drosophila which controls the formation of legs during development. Loss-of-function mutations in the regulatory region of this gene result in the development of the second leg pair into ectopic antennae.

Which is the dominant gain of function mutation in Antp?

There are three classes of dominant gain-of-function mutations within Antp, which often result from chromosomal rearrangements causing Antp expression outside its normal expression domain. Best known is a mutation responsible for the transformation of the adult antennae toward a second thoracic leg ( Fig. 6 (d) ).

How does the Antp gene affect the development of legs?

Antennapedia (abbreviated Antp) is a HOM-C gene first discovered in Drosophila which controls the formation of legs during development. Loss-of-function mutations in the regulatory region of this gene result in the development of the second leg pair into ectopic antennae. By contrast gain-of-function alleles convert antennae into ectopic legs.