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15 Cards in this Set
- Front
- Back
mapping
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process of locating specific genes to their physical location on chromosomes
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two approaches to mapping
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1. genetic mapping - looks at inheritance patterns in families and establishes the order of the genes on the chrom
2. physical mapping - uses various methods of tagging the chrom w/physical markers to establish positions of genes or other DNA sequences on the chromonsomes |
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synteny
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2 genes of DNA seq reside on the same chrom
greek = "same strand" |
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linkage
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2 genes or DNA sequences are inherited together more than expected by random chance
-probability concept -genes MUST be syntenic if they are linked - genes are not nec linked just bc they are syntenic b/c of crossing over Loci on the same chromosome that experience recombination less than 50% of the time are said to be linked |
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centimorgan
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distance between loci
1 cM represents a recombination frequency of approximately 1% theta - stands for centimorgans |
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assessing linkage in families
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statistical odds that 2 loci are a given number of cM apart can be calculated by measuring the ratio of:
- the likelihood of linkage at some specified linkage distance -the likelihood of no linkage (theta =50cM) - Ratios that are >1.0 reflect odds in favor of linkage - Ratios < 1.0 reflect odds against linkage The statistical odds that two loci are a given number of centimorgans apart can be calculated by measuring the ratio of two likelihoods: the likelihood of linkage at a given recombination frequency divided by the likelihood of no linkage - |
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LOD score
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The logarithm of this odds ratio is a LOD score. LOD scores of 3.0 or higher are taken as evidence of linkage, and LOD scores lower than -2.0 are taken as evidence that the two loci are not linked
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linked marker criteria
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to be useful
- codominant - numerous - highly polymorphic - increases the probability that matings will be informative |
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personal biochemistry
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we have a unique biochem environment in which the biochem ( both macro and smlr molecules are in a dynamic process of change
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phenylketonuria
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deficiency of phenylalanine hydrozylase
causes a build up of phenylalanine (blocks it from being converted to tyrosine) |
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tyrosine - negative oculocutaneous albinism
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deficiency of tyrosinase
causes a build up of dopamine (blocks it from becoming melanin) |
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alkaptonuria (AKU)
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deficiency of homogentisic acid oxidase
build up of Homogentisic acid (blocks it from being converted into maleylacetoacetate ) excreted in large quantities in urine -darken on standing "black urine dx" HGA depositied in CT resulting in abn pigmentation and debilitating artheritis loss of fn mutation |
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tyrosinemias
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deficiency of fumarylacetoacetate hydrolase
build up of fumarylacetoacetate ( not broken down into fumarate and acetoacetate) |
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how are most metabolic disorder inherited?
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autosomal recessive
heterozygous carriers usually doesn't affect health |
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How are metabolic disorders tested for?
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dried blood and analyzing for elevated levels of metabolintes in newborn period
carrier and diagnostic testing becoming widely more available |