LESSON-3_Sex-link-inheritance.pdf

SEX-LINKED INHERITANCE LEARNING OBJECTIVES: a. Illustrate the transmission of an X-linked and a Y- linked character; b. Compute the probability of the occurrence of a sex-linked trait; and c. Give examples of other sex-related traits. Sex-linked trait →The gene (pair) that determines...

SEX-LINKED INHERITANCE LEARNING OBJECTIVES: a. Illustrate the transmission of an X-linked and a Y- linked character; b. Compute the probability of the occurrence of a sex-linked trait; and c. Give examples of other sex-related traits. Sex-linked trait →The gene (pair) that determines a character (e.g. hemophilia) is located on the sex chromosomes X- linked trait Y-linked trait Why are sex-linked disorders more common in males than in females? For a recessive allele to be expressed in females, there must be two copies of the allele, one on each of the two X chromosomes. Males have just one X chromosome. Thus, all X- linked alleles are expressed in males, even if they are recessive. X-linked trait A sex-linked trait is where the gene for the trait is found on the X chromosome Hemophilia: x-linked recessive trait Color blindness: x-linked recessive trait HEMOPHILIA  Word Problem Analysis: Hemophilia A woman with hemophilia (XhXh) marries a man who is normal (XHY). a. What is the probability that their children will be hemophiliac? Show in a Punnet square. b. What is the probability that their son will be hemophiliac? c. What is the probability that their daughter will be hemophiliac? X –LINKED TRAITS ❖X-LINKED DOMINANT INHERITANCE ❖X-LINKED RECESSIVE INHERITANCE MODE OF INHERITANCE? Pedigree 1 Pedigree 2 X-Linked Dominant Inheritance Affected/carrier mother = both son and daughter are affected X-Linked Dominant Inheritance a X-Linked RECESSIVE Inheritance X-Linked RECESSIVE Inheritance Pedigree 1 Pedigree 2 X-LINK DOMINANT X-LINK RECESSIVE Assignment: Pedigree C is not an x- linked recessive inheritance because II-I is not affected. If the mother is affected, all sons must have the trait as well. Y-linked Inheritance A sex-linked trait where the gene or allele for the trait is found on the Y chromosome Only males are affected Trait doesn’t skip generations  Hypertrichosis pinnae auris →Y-linked trait where affected males have hair growing from their external ears  Porcupine man A condition where the skin thickens, becomes darker, scaly, rough, and has bristle-like Webbed toes outgrowths A condition where there is a web- like connection between the second and third toes Ichthyosis hystrix SEX-INFLUENCED TRAIT SEX-LIMITED TRAIT Any trait due to genes on Any trait whose expression autosomes, whose expression is is limited to just one affected by an individual’s biological sex biological sex Ex: breast development/ a trait that occurs at a higher lactation; beard growth frequency in one sex over the other Ex: baldness; Facial hair – soft/course OUTPUT NO. 2 – POSTER Create an infographic/poster about a sex-linked trait or disorder (except hemophilia). Will be done by group (Grp 1-12 pedigree groupings) Print your posters on long bond paper. Due: Aug. 27, 2024  CRITERIA POINTS Content. Sufficient information is provided about the 45% trait/ disorder. Organization. Information is very organized with clear 20% ideas and emphasis. Creativity. Layout, design, and graphics used are 30% creative and appropriate. Mechanics. No grammatical, spelling or punctuation 5% errors. Total: 100%