BIOL1008 Lecture Notes - Lecture 32: Epiglottis, Point Mutation, Oncogene
Sex-linked inheritance and chromosomal rearrangements
Sex-linked inheritance
Problems with a gene that is on the X chromosome and behaves in a way that males
and females have different outcomes
E.g. if a male has a fragile X allele they are affected, but when females have a fragile
X chromosome, they are largely unaffected because they have another X
chromosome as a backup
Queen Victoria carried the gene for haemophilia on one of her X-chromosomes- was
enhanced through inbreeding
Sex linked recessive disorders
oFragile X syndrome
oFauvism
If you eat broad beans you die
Heterozygote gives resistance to malaria
oDuchenne’s muscular dystrophy
Muscular degeneration
oHaemophilia
Blood doesn’t clot
E.g. royal family
oColour-blindness
In some cases in females, different parts of the eye are colour blind
due to random X-inactivation
Random X-activation
oIn female mammals, X-chromosome inactivation, of “lysonisation” involves
the shutting down of one X-chromosome in every cell
oIn placental mammals the X’s are randomly turned off
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Document Summary
Problems with a gene that is on the x chromosome and behaves in a way that males and females have different outcomes. E. g. if a male has a fragile x allele they are affected, but when females have a fragile. X chromosome, they are largely unaffected because they have another x chromosome as a backup. Queen victoria carried the gene for haemophilia on one of her x-chromosomes- was enhanced through inbreeding. Sex linked recessive disorders: fragile x syndrome, fauvism. Heterozygote gives resistance to malaria: duchenne"s muscular dystrophy. In some cases in females, different parts of the eye are colour blind due to random x-inactivation. Cancers can be sporadic (mutation affects only the individual) or heritable (genetic basis) Prader-willi syndrome: chromosomal rearrangement, on chromosome 15, section q12 has been deleted from the chromosome, problems at birth, as children, compulsive overeaters, obese, mildly to moderately retarded, short, small hands, feet and genitals.
