1 / 13

4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX-LIMITED INHERITANCE

4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX-LIMITED INHERITANCE. Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123. X-LINKED GENES. Certain traits are governed by genes that are located on a sex chromosome

zuzela
Download Presentation

4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX-LIMITED INHERITANCE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX-LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123

  2. X-LINKED GENES • Certain traits are governed by genes that are located on a sex chromosome • Outcome of cross depends on the genotypes and sexes of parents and offspring • EgDuchenne Muscular Dystrophy (DMD) • A sign of muscular weakness • Eg golden retriever dogs • X-linked recessive • Allele on X-chromosome and recessive • Rare for female

  3. Who’s having what??

  4. X-LINKED INHERITANCE

  5. DMD- DUCHENNE MUSCULAR DYSTROPHY

  6. DISCUSS # 4..

  7. CHROMOSOME-LINKED GENES • Genes located on mammalian sex chromosomes can be transmitted in an X-limited, Y linked or pseudoautosomal pattern • Hemizygous is a condition that describes a single copy of X-linked gene in the male • Few genes are located on the X and some other genes are located on the Y chromosome • The few genes on Y-chromosome are called holandric genes • Y-linked is only transmitted from father to son

  8. SEX-INFLUENCED INHERITANCE • Some traits are influenced by the sex of the individual • In sex-influenced inheritance: • Allele is dominant in one sex but recessive in opposite sex • Genes for sex-influenced traits are autosomal; not on either X, or Y • Heterozygotes phenomenon • Eg baldness • When heterozygote Bb, men will be bald but women don’t.

  9. Baldness • When heterozygote Bb, men will be bald but women don’t. • Transmitted from father to son but not X-linked because father does not supply X

  10. Baldness cont’d • Caused by sex hormone testosterone • Overexpression of an ezyme called 5 α-dihydrotestosterone (DHT) which converts testosterone to DHT • DHT binds to cellular receptors and affects the expression of many genes including those in the cells of the scalp • Because mature men makes more testosterone than female, the allele has greater phenotypic impact on males

  11. SEX-LIMITED INHERITANCE • Trait occur only in 1 of the 2 sexes • Eg breast development in female • Beard development in male • Other examples include rooster and hen where allele H for hen is in hen but not in rooster • Just like sex influenced, these are also influenced by hormone

  12. Limitation to gender because of hormone production

  13. Question.. • You did relative finger length experiment in the lab. • What do you think it is? • X-linked? • Y-linked? • Sex-limited? • Sex-inherited?

More Related