Otherwise the Punnett square is just like any other simple dominance problem. Remember – we use the X’s to designate that the gene is sex-linked. Sex-linked inheritance is a form of mendelian inheritance. 'Sex linkage applies to genes that are located on the sex chromosomes. Xn Y XN XNY XNXn XNXN x XnY XN Carrier female Normal male XNY XNXn Carrier female Normal male Sex linked traits are those controlled by genes on the sex chromosomes, regardless of whether or not they are related to reproduction. Homozygous Normal female & Color Blind male. SEX LINKED TRAITS Set up a Punnett square to show the following. Remember- A male need only have 1 recessive allele to be color blind SEX LINKED TRAITS A male with normal vision can have only ONE genotypeĪ female with color blind vision would have ? Genotype?Ī male with color blind vision would have what Genotype? We put the allele on the X chromosome so we can identify it as a sex-linked traitĪ female that has normal vision can have one of these genotypes. SEX LINKED TRAITS Let N = normal vision Let n = Color Blind THE ALLELES THAT PRODUCE THESE TRAITS ARE RECESSIVE.įOR A FEMALE TO SHOW ONE OF THESE TRAITS SHE MUST HAVE BOTH RECESSIVE ALLELES (like normal).įOR A MALE TO SHOW ONE OF THESE TRAITS HE NEEDS TO HAVE ONLY ONE RECESSIVE ALLELE (he doesn’t have another X chromosome to cover it up!). SEX LINKED TRAITS SOME EXAMPLES OF SEX LINKED TRAITS ARE… COLOR BLINDNESS & HEMOPHILIA

THE GENES FOR A SEX LINKED TRAIT ARE FOUND ONLY ON THE X CHROMOSOME. Cross XY x XXĥ0% XX 50% XY X X X X X X X Girl Girl X Y X Y Y Boy Boy So how is gender determined from a genetic standpoint?Let’s make a Punnett Square. The 23rd pair of chromosomes is different. SEX LINKED TRAITS These are the genetic traits often found more in one gender than the otherĮvery pair of chromosomes in our human cells are identical – except one.

Sex linked traits web game