Chapter 3 Flashcards
what determines sex
the expression of specific genes, which are primarily influenced: chromosomally, genially, or environmentally
chromosomal sex determination
females are homogametic (XX), while males are XY
females are heterogametic (ZW), while males are homogametic (ZZ)
haplodiploidy
system found in some insects in which sex is determined by the ploidy of the individual. males develop from unfertilized eggs and are haploid, females develop from fertilized eggs and are diploid
genic sex determination
sex is determined by genotype, however there are no specific sex chromosomes
these species have sex loci on autosomes
environmental sex determination
temperature of fertilized egg incubation can favor the development of one sex. this is used by several fish and reptile species
SRY gene
sex determining region in humans
sex determination in humans
the SRY gene encodes a DNA biding protein that is thought to affect the expression of genes that influence testes formation
turner syndrome
females with underdeveloped sex characteristics. manly features are common
klinefelter syndrome
persons develop as males and are typically tall with reduced facial hair and testes size
poly x females
individuals develop as females, having no Y chromosome but more than 2 X chromosomes.
typical female features though tall and thin
androgen insensitivity syndrome
individuals develop as females but with XY genotype. no female reproductive organs and testes develop within the abdominal cavity, producing normal testosterone levels
drosophila
developed as a genetic model system that has revealed much about sex-linked characteristics
mary lyons
discovered barr bodies in the 1960s.
how to determine number of barr bodies
number of x chromosomes minus one
