The document describes an experiment testing the hypothesis that when two loci occur on the same chromosome, only two types of gametes will form due to a lack of independent assortment during meiosis. The results found that four recombinant genotypes and gamete types formed, rather than two, disproving the hypothesis. Morgan's experiment provided evidence that independent assortment can occur between loci on the same chromosome during meiosis.
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Recomb.ppt
1. Parental
generation
F1 generation
F2 generation
males
Meiosis I
Meiosis II
w w w
+
w
+
y+
y+
y
y
Phenotype Genotype Number
Female Male
Female Male
X
X
Hypothesis: When two loci occur on one chromosome,
meiosis results in two, rather than four, types of
gametes because independent assortment does not occur.
Results: There are four kinds of gametes rather than
two due to occurrence of two recombinant genotypes.
Novel
genotypes
w+
w+
w
+
w
+
w
w
w w
y y
y
y
y
+
y
+
y+ y+
wy+
/Y
w+
y /Y
wy /Y
w+
y+
/Y
4292
4605
44
86
86
wy
+
/ w
+
y wy+
/ Y
w
+
y / Y
wy+
/ wy+
w+
y
wy
+
Gametes
Red eyes
Yellow body
Gray body
White eyes
Figure 10.15a,b
Linkage hypothesis Morgan’s test of the hypothesis
7. Genes with multiple alleles -
human ABO blood groups
• i allele - not able to produce either a or b
antigens from h antigen
• A allele - able to produce a antigen from h
antigen
• B allele - able to produce b antigen from h
antigen
10. 1. Can you deduce the mechanism of inheritance
of this rare kidney disease?
2. If 1 and 2 marry, what is the probability their
first child will inherit the disease?