Linkage, Recombination and Eukaryotic Mapping Part 2.
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Transcript of Linkage, Recombination and Eukaryotic Mapping Part 2.
![Page 1: Linkage, Recombination and Eukaryotic Mapping Part 2.](https://reader036.fdocuments.net/reader036/viewer/2022062300/56649d095503460f949dbd2f/html5/thumbnails/1.jpg)
Linkage, Recombination and Eukaryotic Mapping
Part 2
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Outline
• Gene mapping in Humans– Pedigrees and linkage
• Physical Chromosome mapping
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Nail-Patella Syndrome
– Autosomal dominant: abnormal fingernails and absent (underdeveloped kneecaps)
– ABO blood type alleles linkage
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2/13= 0.154 recombination frequency
(2 out of 13 offspring)
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Physical Chromosome Mapping
• Provides us alternative methods for gene mapping that do not rely on rates of crossing over to determine gene location
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Methods that are considered “physical mapping of the chromosome”
• Deletion mapping
• Somatic Cell hybridization
• In Situ Hybridization
• DNA Sequencing
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DELETION MAPPING (this has been used to map Muscular Dystrophy gene to X chromosome
50% have mutation all have normal phenotype
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Deletion Mapping
• Can also be done with homozygous recessive
• Homozygous wt+ but with deletion(s)
Deletion area ab
ab
B+B+
Offspring will be:
aB+
We now know this deletion includes the locus that is within the region deleted for A+ but not for B+
Crossed with
ab
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deletion 1
deletion 2deletion 3
deletion 4
deletion 5
deletion 6
chromosome
f? a f? c e d b
Mutations del a b c d e
f1 m + m + +
m2 m + + + +
+3 + m m m m
+4 + + m m m
+5 + + + m m
+6 + m + m +
+
You can perform this a panel of deletions.
a c detc.
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SOMATIC CELL HYBRIDIZATION
+ Human somatic cell
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You set up a panel of these hybrid cells that include a random selection of human chromosomes
Look for which cell lines produce the product AND which chromosomes are present.
Bingo! You can determine which gene is associated with which chromosome!
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In Situ Hybridizationdetects genes on chromsomes
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DNA SEQUENCING
More to come with our molecular discussions
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Practice Physical Mapping
• Questions 4, 5, 26 and 27 at the back of chapter 7 to try out your skills at deletion analysis and somatic-cell hybridization.
• I will post the answer for question 26 (others are in the book).
• Does not have to be handed in—just to practice to see if it all makes sense.
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The End