Breeding management and genetics

Mendel's first law

• the principle of segregation states that the two members of a gene pair segregate from each other in the formation of gametes

Mendel's second law

• the principle of independent assortment states that members of different gene pairs are transmitted independently of one another during gamete production

Test cross

• a cross between an individual of an unknown genotypes and an individual that is true breeding for the recessive trait 

Sex chromosomes - mammals

• ** = female
• XY = male
• evidence found when chromosome dis-junction occurs 
  • XO = turner syndrome - females have only 45 chromosomes. 1 in 10,000 but up to 99% of embryos die before birth. Appear normal until puberty. Fail to develop secondary sex characteristics. Shorter then average, weblike necks, poorly developed breasts. Reduced ability to interpret spatial relationships. Infertile. 
  • **Y = klinefelter syndrome - 1 in 1,000 males. Underdeveloped testes, taller then average. Some breast development, some show subnormal intelligence.
  • XYY = **Y syndrome - 1 in 1,000 males. Taller then average, can have adverse affects on…