2DN 103 T/F Every chromosome is different between a man and a woman T/F Men and women have different numbers of chromosomes in their sex cellsT/F If you looked in a cell during mitosis and you could see the chromosomes lining up, you could tell whether the cell belonged to a man or a woman
6Sex-Linked DisordersHow would a person inherit a sex-linked disorder?
7Sex-Linked DisordersY chromosome does not carry all of the genes of an X chromosomeFemales have two X chromosomes, so they carry two copies of each gene found on the X – backup!Genes for certain disorders are carried on X chromosome
8Sex-Linked DisordersBecause the gene for these is recessive, and men only have 1 X chromosome, men are more likely to have sex-linked disorders (if they have the gene, they will express it – diseases like this are called HEMIZYGOUS)Women need two copies of the gene to express itMen only need ONEColorblindness – inability to distinguish between red/greenHemophilia - Prevents blood from clotting – even small cuts can be fatal
26Briggs Family DISASTER Nick and Caroline both suffer from the disease.Assuming Michael gets married to someone who doesn’t have the disease, and is not a carrier, can his children get the disease?
27Recessive vs. Sex-Linked What is the difference between recessive traits and sex-linked traits?How does this change the pedigree chart?
28Recessive vs. Sex-Linked If a trait is carried on the X chromosome, women are carriers. They have a back-up X chromosome in case of a mutation.Remember:Women need two copies of the gene to express itMen only need ONEMen…Do NOT have a back up X chromosomeIf Mom is carrying the gene, men have a chance of suffering from the disease!