EDU 541 Etiology of Disability

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EDU 541Etiology of Disability

• Jeff McNair,Ph.D.
• California Baptist University

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Normal Karyotype
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Too many chromosomes
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Too many chromosomes
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Too few chromosomes
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Trisomy 21 Nondisjunction during meiosis
46
23
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Polar bodies
46
22
24
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Egg with extra 21 chromosome, 24 altogether
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23
23
Sperm with normal chromosome complement
47
Fertilized egg with 47 chromosomes Including 3
21
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Mosaic Downs Nondisjunction during mitosis
23
23
46
46
46
46
46
46
46
46
46
46
46
45
47
46
46
47
47
46
46
Cell line has down syndrome
46
46
46
46
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Mosaic Downs Nondisjunction during mitosis
23
23
46
46
46
46
46
46
46
Cell line has down syndrome
47
46
46
45
47
46
46
46
46
47
46
46
46
46
46
46
46
46
46
46
46
46
Cell with 45 chromosomes not viable
14
21
14
14
21
21
14
21
14
14/21
14/21
14/21
14/21
Translocation Carrier
14
21
14
14
21
21
Translocation down syndrome
Normal
15
21
14
14
21
21
14
21
14
14/21
14/21
14/21
14/21
14
21
14
14
21
21
Translocation down syndrome
16
21
14
14
21
21
14
21
14
14/21
14/21
14/21
14/21
14
21
14
14
21
21
Translocation down syndrome
17
21
14
14
21
21
14
21
14
14/21
14/21
14/21
14/21
14
21
14
14
21
21
Translocation down syndrome
18
21
14
14
21
21
14
21
14
14/21
14/21
14/21
14/21
14
21
14
14
21
21
Translocation down syndrome
19
21
14
14
21
21
14
21
14
14/21
14/21
14/21
14/21
14
21
14
14
21
21
Translocation down syndrome
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21
14
14
21
21
14
21
14
14/21
14/21
14/21
14/21
14
21
14
14
21
21
Translocation down syndrome
21
21
14
14
21
21
14
21
14
14/21
14/21
14/21
14/21
1/3
Lethal
Lethal
Normal
14
21
1/3
1/3
Translocation downs
Trisomy 14 lethal
14
14
21
21
Translocation down syndrome
Translocation carrier
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Key Terms in Mendelian Genetics Allele each
gene on a chromosome has a mate on the other
chromosome of the same type within a
cell Dominant gene gains expression Recessive
gene expressed only when no dominant allele is
present Homozygous both genes in an allelic
pair are the same Heterozygous genes in
allelic pair are different Carrier a person
who carries a recessive gene which has its
effects masked by a dominant gene Genotype
genes which make up a person Phenotype -
expression of the genes, what a person looks
like Concepts Genes only dictate the limits of
expression Genes provide the potential, diet,
disease, etc. influence the degree of
attainment Genes usually have the capacity to
produce twice as much of a specific protein as is
needed therefore a person with one Dominant
gene has about the same phenotype as a person
with two
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Autosomal Dominant
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Autosomal Recessive