Linkage

Dioecious

species separate sexes

monoecious

hermaphrodites, species has both sexes

differentiated sex chromosomes

morphologically different sexes, ex: mammals

Undifferentiated sex chromosomes

the early embryonic phase when reproductive structures are identical in all embryos and have the potential to develop into either male or female anatomy

single-gene based systems

a single chromosome that determines whether a haploid cell acts as a mating type a or alpha a

environment sex determination

a biological process where external, non genetic factors in an organisms environment dictate its sex during critical development windows

Autosomes

each homologous pair consists of two morphologically-identical chromosomes

sex chromosomes

the chromosome types contributed by mom and dad are different (X from mom, Y from dad)

Homogametic sex

sex containing two like sex chromosomes (x vs xx)

heterogametic sex

sex containing two unlike sex chromosomes (XY vs XX)

Mammalian X

gene rich

Mammalian Y

very few genes

Pseudoautosomal regions on Y

on the Y chromosome are homologous (matching) segments of DNA shared with the X chromosome that pair and recombine during male meiosis

haplo-diploid system

Haploids = male, diploids = female

sex determining region Y

area on the y chromosome (only) that when activated causes gonads to produce testes, which in turn produces testosterone

androgen-insensitivity syndrome

have internal testes, but are phenotypically female (sterile, do not menstruate)

dosage compensation

a genetic regulatory mechanism that equalizes X-linked gene expression between males and females.

X inactivation

the biological process by which female mammals shut down one of their two chromosomes in each cell. Once a cell chooses an X to silence, all its future daughter cells keep that same X inactive.

sex linkage

consequences of genes being on sex chromosomes, as opposed to autosomes

reciprocal crosses

a pair of crosses where the sexes of the parents are reversed to see if the trait’s inheritance depends on the parents sex

hemizygous

having only one single copy of a gene or chromosome segment instead of the usual pair of two alleles in a diploid organism. (male mammals XY)

independent assortment

a genetic rule stating that the alleles for different traits segregate independently of one another during the formation of gametes

imprinting

a genetic phenomena that can mimic sex-linkage (difference in reciprocal crosses) hence, the sex that transmits the allele influences its phenotype.