Mendel and the re-discoverers of genetics Correns, dc Vries and Tschermak identi
ID: 308000 • Letter: M
Question
Mendel and the re-discoverers of genetics Correns, dc Vries and Tschermak identified discrete traits whose patterns of inheritance followed interpretable rules. But most traits found in animals and plants were continuous, not discrete, and tended to mix in offspring - when you cross a Labrador and a poodle (two breeds of dogs), you get a labradoodle, not Labradors that give a 3:1 ratio of Labradors and poodles in the next generation. Explain the concept of a gene resulting from the work of Mendel, and use it to explain the appearance of labradoodles. Keep in mind not all dogs are Labradors or poodles.Explanation / Answer
Mendel and the re-discoverers of genetics Correns,de Vries and Tschermak identified discrete traitswhose patterns of inheritance followed interpretablerules.But most traits found in animals and plantswere continuous, not discrete, and tended to mix in offspring – when you cross a Labrador and a poodle(two breeds of dogs), you get labradoodles, not Labradors that give a 3:1 ratio of Labradors and poodles in the next generation. Explain the concept of a gene resulting from the work of Mendel, and use it to explain the appearance of labradoodles. Keep in mind that many dogs are neither poodles nor Labradors
ANSWER :
Labrador + Poodle = Labradoodle
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COLOR IS DETERMINED BY
ALLELE AT LOCI B AND E
AND EPISTATIC NATURE OF ALLELES OF COLOR
labrador genotype
at B locus;
black gene dominant over the chocolate gene which is called recessive.
BB = black Lab, no chocolate gene
Bb = black Lab, carries chocolate gene
bb = chocolate Lab, no black gene
Two black genes (BB) gives ------------à black Labrador
One of each (Bb)also give ----------àblack Labrador
Two brown genes (bb) gives ----------àchocolate Labrador
Alleles at locus E, influences the color of ----------à
Genotype
Phenotype
EEBB
Black
EEBb
Black
EEbb
Brown
EeBB
Black
EeBb
Black
Eebb
Brown
eeBB
Yellow
eeBb
Yellow
eebb
Yellow
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Labradoodle=
A black labradoodle can have one of 4 different genotypes.
BBEE
BBEe
or
The yellow labradoodle with the genotype
BB ee
, because of the two dominant alleles BB
, means that it does not carry the recessive brown gene b
. So this dog cannot produce brown (chocolate/cafe/parchement) puppies.
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The yellow labradoodle with the genotype Bb ee ; because of the recessive allele b
===============================================================
Because of epistatic nature of allele in Labrador , which doesnot give 3:1 ratio in next generation
Genotype
Phenotype
EEBB
Black
EEBb
Black
EEbb
Brown
EeBB
Black
EeBb
Black
Eebb
Brown
eeBB
Yellow
eeBb
Yellow
eebb
Yellow