Sex-linked inheritance refers to traits that are determined by genes located on the sex chromosomes (X and Y in humans). Since females have two X chromosomes (XX) and males have one X and one Y chromosome (XY), the inheritance patterns differ between the sexes. Most sex-linked traits are X-linked, meaning the gene responsible for the trait is located on the X chromosome. These traits can be recessive or dominant.
Understanding sex-linked inheritance is crucial for predicting the probability of offspring inheriting certain traits or conditions, such as hemophilia or color blindness. Punnett squares are often used to visualize and calculate these probabilities, considering the genotypes of both parents and the specific location of the gene on the X chromosome.
Match the terms with their definitions:
| Term | Definition |
|---|---|
| 1. Sex-linked gene | A. Having two different alleles for a trait |
| 2. X-linked | B. A person who carries a recessive allele but does not express it |
| 3. Heterozygous | C. Gene located on a sex chromosome |
| 4. Carrier | D. Expressing a trait even with only one copy of the allele |
| 5. Dominant | E. Gene located on the X chromosome |
Sex-linked traits are often inherited differently in males and females because males only have one ___(1)___ chromosome. A female needs to inherit ___(2)___ copies of a recessive X-linked allele to express the trait, while a male only needs ___(3)___. Females who have one copy of the recessive allele are called ___(4)___, and they do not express the trait but can pass it on to their ___(5)___.
A woman who is a carrier for hemophilia (an X-linked recessive disorder) has children with a man who does not have hemophilia. What is the probability that their son will have hemophilia? Explain your reasoning.
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