Term
| Approx how many genes are on the X-Chromosome? |
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Definition
| 1150 genes (with diverse functions, most unrelated to sex determination) |
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Term
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Definition
| traits coded for by genes on the x-chromosome. x-linked traits use a superscripts to represent alleles (X^A=dominant, X^a=recessive) |
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Term
| T/F- Most genes on the x chromosome are expressed in males |
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Definition
| True. Males only receive one x chromosome so most genest on that chromosome are expressed. |
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Term
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Definition
| EVERY gene is expressed!! whether dominant or recessive-- happens in males because only have one x chromosome. |
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Term
| T/F- abnormal alleles are more often expressed in males than females |
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Definition
| True. Because males have only one x chromosome, they express ALL genes--including recessive and abnormal alleles. |
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Term
| Examples of Sex-Linked Disorders occurring more frequently in males: |
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Definition
| Muscular Dystrophy, hemophilia, color blindness, fragile X-syndrome, kinky hair syndrome |
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Term
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Definition
| each autosomal cell in the female has one x-chromosome inactivated--controlled by a gene on the x-chromosome called "Xist". Inactivated X shows up as a "barr body" in cells. |
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Term
| T/F- X-inactivation may increase Autoimmune Diseases in women. |
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Definition
| True. Women havea higher incidence of most autoimmune diseases due to immune cell reaction to x-inactivation |
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Term
| Is there any parental influence over which x-chromosome is inactivated? |
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Definition
| Yes. The influence is outside the gene, during early development, and is called IMPRINTING. |
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