Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Skewed X-inactivation wikipedia , lookup
Genetic drift wikipedia , lookup
Hardy–Weinberg principle wikipedia , lookup
Neocentromere wikipedia , lookup
Causes of transsexuality wikipedia , lookup
Y chromosome wikipedia , lookup
X-inactivation wikipedia , lookup
Sexual dimorphism wikipedia , lookup
Sex Determination - Sex is determined by the 23rd pair of chromosomes – called the sex chromosomes - Chromosome pairs #1-22 are called autosomes - Females have two X chromosomes while males have an X and a Y, ie, the 23rd pair in males is NOT homologous – the Y chromosome is shorter and does not carry the same genetic information as the X - There are no matching alleles on males’ 23rd pair Chances of having a male or female child: P1 XX X Y X XX XY X XX XY 50% males 50% females x XY Sex-Linked Traits (x-linked traits) - - - some traits seem to occur in males more often than females (Ex: Colour blindness (types), hemophilia, muscular dystrophy, male pattern baldness … why?) Alleles for these diseases are carried on the X chromosomes, so if a male receives a defective X from his mother he will get the disease because he does not have a compensating allele on his Y A woman would have to get two defective copies in order to have the disease (Note: these diseases are usually recessive) How males and females get an X-linked disease: Alleles: Xr – colour blind XR – normal vision P1: XRXr x Xr Y XR XRXr XRY Xr XrXr XrY XrY 25% XRXr – Carrier female (does not have the condition) 25% XrXr – female with the condition (2 copies of the defective allele) 25% XRY - normal male (1 copy of normal allele) 25% XrY - male with the condition (1 copy of defective allele)