1. Patterns of Inheritance sex linked traits

2. Review How many chromosomes do each of our cells have? 46
Do all of these chromosomes have the same function, or do they all serve a different purpose?
They are different; each individual chromosome has specific proteins that control certain traits.

3. Chromosomes 46 chromosomes are found in each of our cells.
22 pairs of autosomes (body chromosomes)
1 pair of sex chromosomes (XX or XY)
* Remember *
Males and Females have
two different sex chromosomes
Males = XY Females = XX

4. Sex Chromosomes
The X chromosome carries a variety of genes that are necessary for the development of both females and males.
The Y chromosome mainly has genes that relate to the development of male characteristics.

5. Sex-Linked Traits
So far, all of the traits that we have discussed are found on the autosomes.
Any gene that is carried on either the X or Y chromosome in known as a sex-linked gene.
Therefore, the trait that is shown due to this gene is called the sex-linked trait.
Most sex-linked traits (or diseases) are carried on the X chromosome.
Very few are carried on the Y chromosome.

6. Notation for sex-linked traits
If the majority of sex-linked traits/diseases are carried on the X chromosome, who is more likely to be affected?
Males or Females
Since males have only one X chromosome, they are affected by recessive X-linked traits more often than females.
This time we have to show the chromosomes.
R = Red Eyes r = White Eyes
XRXR = Red Eyes
XRXr = Red Eyes
XrXr = White Eyes
XRY = Red Eyes
XrY = White Eyes

7. Dominant or Recessive
Sex-linked traits can still be dominant or recessive.
XRXR = Homozygous Dominant
XRXr = Heterozygous
XrXr = Homozygous Recessive
XRY = Dominant
XrY = Recessive

8. Examples of Sex-Linked Traits
Red-Green color blindness
Insensitive to green and purplish-red
~ 8% of males in the U.S. have red-green color blindness

9. How is it passed on?

10. Are you color blind?