Genetics - Sex inheritance and Sex Linkages

(part 3)

(key: Chromo(s) - Chromosome(s))

Sex inheritance in humans

• sex determined by chomosomes
• females: 2X chromosomes, all female gametes are the same having X's
• males : 1X, 1Y producing two types of gamete- 50% X , 50% Y

sex linkage - Haemophilia:

• any gene carried on X/Y chromos are sex linked
• X is longer than Y so on most of X's length, there is no equivilent homologous portion of the Y chromosome.
• those characteristics conrolled by recessive alleles on the non homologous part of the X appears frequently in Males.

• there is no homologous portion on Y which may carry a dominant allele.
• X chromos carries many genes
• in haemophilia, blood clots slow, and has slow constant jointal bleeding.

• this resulted…