sex determination Flashcards
(8 cards)
what determines sex
in humans, sex is determined by X and Y chromosomes. the sex determining region of the Y chromosome (SRY) gene is responsible for the initiation of male sex determination. it attaches itself to DNA molecules and makes it available for transcription. these genes that can be transcribed are the ones that lead to testes development
why does the Y look shorter than x chromosome
It has less genes.
explain x linked recessive disorder
females have homozygous recessive genotype. with males, if they are affected, they are homizygous -not homologous
if someone is heterozygous and a carrier, what is their phenotype
no or mild symptoms
in sex linked disorders wha need stop happen for a female to be affected
both parents need to have the disorder
Explain how X chromosome inactivation can lead to haemophilia manifestation in female
carriers
haemophilia is a clotting deficiency. abnormal alleles code for proteins that cannot participate effectively in blood clotting processes. A and B are X disorder. X linked disorder an epigenetic mechanism that influences the diversity in phenotypes for female characters is X chromosome inactivation (lionisation) may lead to female carriers having diversity of symptoms- this occurs because of the 2 X chromosomes and some of them are important development genes. we have evolved to have this mechanism to have half the x chromosomes switched off- his could be paternal or maternal. this is random but 50% is usually from mum and 50% from dad. this means that 50% of normal chromosome is on and other is defective.
what happens if a father is affected with a dominant sex linked disorder
it will be passed to all his daughters but not his sons- because girls need two X- one from mum and one from dad.
