#genetics

• Self-sterility — A congenital physiological or genetic incompatibility of certain hermaphroditic plants or animals to achieve fertilization through the union of their own gametes (self-fertilization), although these gametes are fully viable and functional when combined with those of other individuals. This structural adaptive mechanism prevents inbreeding and forces cross-pollination, ensuring the genetic variability and biological vigor of the species' offspring.
• Autotetraploid — A polyploid organism or cell possessing four identical sets of chromosomes (4n), all derived through the multiplication or duplication of the base chromosome set of the same species, without interspecific hybridization. This structural genetic phenomenon, frequently encountered in the plant kingdom, often leads to plants with larger vegetative organs, bulkier flowers, and increased resistance to environmental factors.
• Autozygote — A zygote or diploid organism possessing identical alleles at a specific genetic locus, genes that have been inherited directly from a common ancestor through inbreeding or self-fertilization; an individual homozygous by direct descent (identity by descent).
• Autosome — Any of the somatic chromosomes in a cell, identical in number and structure in both sexes of the same species, containing genes responsible for somatic traits and general body functions, defining the biological profile independent of sex chromosomes (heterosomes). In humans, there are exactly 22 pairs of autosomes.
• Auxocyte — An animal or plant germ cell during its stage of intense growth and development prior to entering the meiotic division process; a general term that encompasses primary spermatocytes and oocytes during their meiotic growth phase.
• Auxomery — A structural type or rare biological variation characterized by the unequal division or multiplication of chromosomal segments or metameric structures, leading to a macroscopic differentiation in the growth rate and enlargement of homologous organs of the same plant or living organism.
• Auxotroph — A mutant organism (especially a bacterial or fungal strain, or a cell culture) that has lost the ability to synthesize a specific organic compound essential for its growth (an amino acid, vitamin, or nitrogenous base) due to a genetic mutation, requiring the mandatory presence of this substance as an exogenous supplement in the culture medium to multiply.
• Azygoid — Pertaining to a haploid organism, cell, or biological structure developed through parthenogenesis, lacking a homologous pair; a biological entity that possesses a single set of chromosomes and develops directly from an unfertilized egg, bypassing the zygote stage.
• Azygote — A haploid organism or cell resulting from a parthenogenetic developmental process, without prior fertilization of gametes; an individual that develops directly from an unfertilized egg, possessing a single set of chromosomes and lacking paired genes.