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Hox genes, a subset of homeobox genes, are a group of related genes that specify regions of the body plan of an embryo along the head-tail axis of animals. Hox proteins encode and specify the characteristics of 'position', ensuring that the correct structures form in the correct places of the body.
Phylogenetic analysis of homeobox gene sequences and homeodomain protein structures suggests that the last common ancestor of plants, fungi, and animals had at least two homeobox genes. [21] Molecular evidence shows that some limited number of Hox genes have existed in the Cnidaria since before the earliest true Bilatera , making these genes ...
Homeotic genes are genes which regulate the development of anatomical structures in various organisms such as echinoderms, [1] insects, mammals, and plants. Homeotic genes often encode transcription factor proteins, and these proteins affect development by regulating downstream gene networks involved in body patterning.
ABC model of flower development guided by three groups of homeotic genes.. The ABC model of flower development is a scientific model of the process by which flowering plants produce a pattern of gene expression in meristems that leads to the appearance of an organ oriented towards sexual reproduction, a flower.
Hox genes determine where repeating parts, such as the many vertebrae of snakes, will grow in a developing embryo or larva. [9] Pax-6, already mentioned, is a classic toolkit gene. [48] Although other toolkit genes are involved in establishing the plant bodyplan, [49] homeobox genes are also found in plants, implying they are common to all ...
In plants, MADS-box genes are involved in controlling all major aspects of development, including male and female gametophyte development, embryo and seed development, as well as root, flower and fruit development. [12] [13] Some MADS-box genes of flowering plants have homeotic functions like the HOX genes of animals. [1]
In plants, however, the developmental genes affected by homeosis may control anything from the development of a stamen or petals to the development of chlorophyll. [2] Homeosis may be caused by mutations in Hox genes , found in animals, or others such as the MADS-box family in plants.
From the example above, if the descendant with genes A1 and B underwent another speciation event where gene A1 duplicated, the new species would have genes B, A1a, and A1b. In this example, genes A1a and A1b are symparalogs. [1] Vertebrate Hox genes are organized in sets of paralogs. Each Hox cluster (HoxA, HoxB, etc.) is on a different chromosome.