Related topics: genes

When determining sex, exceptions are the rule

For nearly a century, biologists have modeled the evolution of sex chromosomes—the genetic instructions that primarily determine whether an individual will develop into a male or female (or a certain mating type)—resulting ...

The surprising structure of a shrub willow sex chromosome

Sex in plants can be befuddling. Most species are hermaphrodites, expressing both male and female gametes in one individual. But some, including shrub willow Salix purpurea, employ the evolutionary strategy we are far more ...

Record-size sex chromosome found in two bird species

Researchers in Sweden and the UK have discovered the largest known avian sex chromosome. The giant chromosome was created when four chromosomes fused together into one, and has been found in two species of lark.

Genes linked to sex ratio and male fertility in mice

One of the more recent trends among parents-to-be is the so-called gender reveal, a party complete with pink or blue cake to answer the burning question, "Is it a boy or girl?" After all, it's presumed that there's a 50-50 ...

Breakthrough in sex-chromosome regulation

Researchers at Karolinska Institutet in Sweden have uncovered a chromosome-wide mechanism that keeps the gene expression of sex chromosomes in balance in our cells. The findings shed light on molecular reasons for early miscarriage ...

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Sex-determination system

A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. Most sexual organisms have two sexes. In many cases, sex determination is genetic: males and females have different alleles or even different genes that specify their sexual morphology. In animals, this is often accompanied by chromosomal differences. In other cases, sex is determined by environmental variables (such as temperature) or social variables (the size of an organism relative to other members of its population). The details of some sex-determination systems are not yet fully understood.

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