Specialized Mapping Specialized Mapping Finding Chromosomal Finding Chromosomal Locations Locations Using Tetrad Analysis To Using Tetrad Analysis To Study Study Genetic Distances Genetic Distances (see Tetrad Analysis Web (see Tetrad Analysis Web Module for Module for Chapter 7 on Text Web Site Chapter 7 on Text Web Site
Specialized Mapping. Finding Chromosomal Locations Using Tetrad Analysis To Study Genetic Distances (see Tetrad Analysis Web Module for Chapter 7 on Text Web Site http://whfreeman.com/pierce/ ). Physical Chromosome Mapping. Somatic-Cell Hybridization - PowerPoint PPT Presentation
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Specialized MappingSpecialized Mapping
Finding Chromosomal LocationsFinding Chromosomal LocationsUsing Tetrad Analysis To Study Using Tetrad Analysis To Study Genetic Distances Genetic Distances (see Tetrad Analysis Web Module for (see Tetrad Analysis Web Module for Chapter 7 on Text Web Site Chapter 7 on Text Web Site http://whfreeman.com/pierce/))
Using human-rodent somatic cell Using human-rodent somatic cell hybrids to study the location of hybrids to study the location of genes on chromosomesgenes on chromosomes
Human-mouse hybrid cells with different Human-mouse hybrid cells with different numbers of human chromosomes (blue).numbers of human chromosomes (blue).
• How can we determine which How can we determine which chromosome carries a specific gene? chromosome carries a specific gene?
In human-mouse hybrid cells, a 1:1 In human-mouse hybrid cells, a 1:1 correspondence exists between the correspondence exists between the presence of the enzymatic activity for presence of the enzymatic activity for the gene and the presence of the the gene and the presence of the chromosome carrying the gene.chromosome carrying the gene.
Problem 4, Page 2-2Problem 4, Page 2-2
55 77 1111 1818
AA -- ++ ++ --
BB ++ -- ++ ++
CC -- ++ ++ ++
DD ++ ++ -- --
Human ChromosomeHuman Chromosome
Hyb
rid C
ell
Lin
eH
ybri d
Ce
l l Li
ne
ADHADH PEPPEP HexAHexA GAPDHGAPDH
AA ++ -- ++ --
BB ++ ++ -- ++
CC ++ -- ++ ++
DD -- ++ ++ --
Human EnzymeHuman Enzyme
Hyb
rid C
ell
Lin
eH
ybri d
Ce
l l Li
ne
Hybrid cells containing human and mouse chromosomes Hybrid cells containing human and mouse chromosomes were analyzed. The grid on the left shows the presence were analyzed. The grid on the left shows the presence or absence of each of four human chromosomes in hybrid or absence of each of four human chromosomes in hybrid cell lines A through D. The grid on the right shows the cell lines A through D. The grid on the right shows the presence or absence of human enzyme activity in each of presence or absence of human enzyme activity in each of the cell lines. Assign the gene for each enzyme to the the cell lines. Assign the gene for each enzyme to the chromosome that carries the gene. chromosome that carries the gene.
• How can we determine which portion of How can we determine which portion of a chromosome carries a specific gene? a chromosome carries a specific gene?
If the enzymatic activity is present in a If the enzymatic activity is present in a cell line with an intact chromosome but cell line with an intact chromosome but missing from a line with a deletion in that missing from a line with a deletion in that chromosome, the gene for the enzyme chromosome, the gene for the enzyme is in the deleted region. is in the deleted region.
Enzyme ActivityEnzyme Activity
Present with intact Present with intact Chromosome 4Chromosome 4
Absent without Absent without Chromosome 4Chromosome 4
Absent when Absent when short arm of short arm of
Chromosome 4Chromosome 4is deletedis deleted
Gene is located on the short arm of Chromosome 4, in the region missing from Cell line 3
Tetrad AnalysisTetrad Analysis
• Analysis of all four products of a Analysis of all four products of a single meiosis single meiosis
In a In a NeurosporaNeurospora cross of ab x a cross of ab x a++bb++, the , the following classes and numbers of following classes and numbers of tetrads were produced. tetrads were produced. NeurosporaNeurospora produces ordered tetrads that undergo produces ordered tetrads that undergo a single mitosis after formation. Pairs of a single mitosis after formation. Pairs of spores are listed below for simplicity. spores are listed below for simplicity.
Problem 2, Page 2-1Problem 2, Page 2-1
abab
abab
aa++bb++
aa++bb++
abab++
abab++
aa++bb
aa++bb
abab
abab++
aa++bb++
aa++bb
abab
aa++bb
aa++bb++
abab++
abab
aa++bb++
aa++bb++
abab
abab++
aa++bb
aa++bb
abab++
abab++
aa++bb
aa++bb++
abab
7171 11 1818 11 88 00 11
TypeType
For aFor a
For bFor b
Problem 2, Page 2-1Problem 2, Page 2-1
abab
abab
aa++bb++
aa++bb++
abab++
abab++
aa++bb
aa++bb
abab
abab++
aa++bb++
aa++bb
abab
aa++bb
aa++bb++
abab++
abab
aa++bb++
aa++bb++
abab
abab++
aa++bb
aa++bb
abab++
abab++
aa++bb
aa++bb++
abab
7171 11 1818 11 88 00 11
TypeType
For aFor a
For bFor b
NPDNPD
MMII
MMII
TT
MMII
MMIIII
TT
MMIIII
MMII
PDPD
MMIIII
MMIIII
NPDNPD
MMIIII
MMIIII
PDPD
MMII
MMII
TT
MMIIII
MMIIII
Problem 2, Page 2-1Problem 2, Page 2-1
Distance from aDistance from a centromere = centromere =½ M½ MII II = = ½ (1+8+1)½ (1+8+1) = 0.05 = 5 map units = 0.05 = 5 map units
TotalTotal 100 100
Distance from bDistance from b centromere = centromere =½ M½ MII II = = ½ (18+8+1)½ (18+8+1) = .135 = 13.5 map units = .135 = 13.5 map units
TotalTotal 100 100
Distance from aDistance from ab =b =½ T + NPD½ T + NPD = = ½ (18+1+1) +1 ½ (18+1+1) +1 = .11 = 11 map units= .11 = 11 map units