4- x-linked genes, sex influenced inheritance, sex- limited inheritance compiled by siti sarah...
TRANSCRIPT
![Page 1: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/1.jpg)
4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX-LIMITED INHERITANCE
Compiled bySiti Sarah JumaliLevel 3 Room 14
Ext 2123
![Page 2: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/2.jpg)
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
• Eg Duchenne Muscular Dystrophy (DMD)– A sign of muscular weakness
• Eg golden retriever dogs
– X-linked recessive• Allele on X-chromosome and recessive• Rare for female
![Page 3: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/3.jpg)
Who’s having what??
![Page 4: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/4.jpg)
X-LINKED INHERITANCE
![Page 5: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/5.jpg)
DMD- DUCHENNE MUSCULAR DYSTROPHY
![Page 6: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/6.jpg)
DISCUSS # 4..
![Page 7: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/7.jpg)
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
![Page 8: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/8.jpg)
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.
![Page 9: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/9.jpg)
Baldness
Male Female
BB Bald Bald
Bb Bald Nonbald
bb Nonbald nonbald
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
![Page 10: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/10.jpg)
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
![Page 11: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/11.jpg)
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
![Page 12: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/12.jpg)
Limitation to gender because of hormone production
Female Male
hh Hen-feathered Cock-feathered
Hh Hen-feathered Hen-feathered
HH Hen-feathered Hen-feathered
![Page 13: 4- X-LINKED GENES, SEX INFLUENCED INHERITANCE, SEX- LIMITED INHERITANCE Compiled by Siti Sarah Jumali Level 3 Room 14 Ext 2123](https://reader036.vdocument.in/reader036/viewer/2022062223/551bb9a6550346b9588b45c0/html5/thumbnails/13.jpg)
Question..
• You did relative finger length experiment in the lab.
• What do you think it is?– X-linked? – Y-linked? – Sex-limited? – Sex-inherited?